Introduction In this lesson, we'll look at what a servo motor is and how it works. First, let's define what a servo motor is and look at some of the unique characteristics of the different types of servo motors and their applications. You will also learn how to control Servo Motors with an Arduino and a Raspberry Pi in this blog. Introduction Ⅰ What is a Servo Motor? Ⅱ Servo Motor Related Video: Ⅲ Types of Servo Motors 3.1 AC or DC 3.2 Brushed or Brushless 3.3 Synchronous or Asynchronous Ⅳ Servo Motor Working Principle Ⅴ Applications of Servo Motors Ⅵ Difference Between Stepper Motor and Servo Motor  Ⅶ Servo Motors Control with an Arduino  7.1 Experiment 1 Ⅷ Control with  Raspberry Pi 8.1 PWM (Pulse Width Modulation) 8.2 Components Required 8.3 Circuit Diagram 8.4 Working and Programming Explanation 8.5 Code Ⅸ FAQ   Ⅰ What is a Servo Motor? A servo motor is a self-contained electrical device that rotates machine parts with high efficiency and precision. This motor's output shaft can be moved to a specific angle, position, and velocity that a standard motor cannot. The Servo Motor  combines a standard motor with a sensor to provide positional feedback. The most important component of the Servo Motor  designed and used specifically for this purpose is the controller  . Figure1:Servo Motor      Ⅱ Servo Motor Related Video:   How servo motor works   Servo Motor Video Description: This movie gives an overview of how RC servo motor works and how it's made.   Ⅲ Types of Servo Motors Servo motors are classified into two types based on their application: AC servo motors  and  DC  servo motors. There are three major factors to consider when evaluating servo motors. The first type of consideration is the current type –  AC  or  DC – and the second type of consideration is the type of commutation used, whether the motor uses brushes. The third type of consideration is the motor's rotating field, the rotor, and whether the rotation is synchronous or asynchronous.   3.1 AC or DC Let's start with the first servo consideration. The most fundamental classification of a motor is based on the type of current it will use. When it comes to performance, the primary distinction between  AC and DC motor  s is their inherent ability to control speed. Figure2:DC or AC Servo Motor  With a constant load, the speed of a DC motor  is directly proportional to the supply voltage. The frequency of the applied voltage and the number of magnetic poles determine the speed of an alternating current motor.   Figure3:DC or AC Servo Motor  While both AC and DC motor  s are used in servo systems, AC motors  can handle more current and are more commonly used in servo applications such as robots, in-line manufacturing, and other industrial applications requiring high repetitions and precision.   3.2 Brushed or Brushless The next step is to decide whether to use a brushed or brushless finish. A DC Servo Motor  can be commutated mechanically with brushes, electronically without brushes, or mechanically with a commutator. Brushed motors are less expensive and easier to operate in general, whereas brushless designs are more reliable, have higher efficiency, and are quieter.   Figure4:brushed or brushless Servo Motor  A commutator is a rotary electrical switch that reverses the current direction between the rotor and the drive circuit on a regular basis. It is made up of a cylinder made up of multiple metal contact segments on the rotor. Two or more electrical contacts known as "brushes" made of a soft conductive material such as carbon press against the commutator, making sliding contact with commutator segments as it rotates. Figure5:brushed or brushless Servo Motor  While the majority of servo motors are AC brushless designs, brushed permanent magnet motors are occasionally used as servo motors due to their simplicity and low cost. The permanent magnet DC motor  is the most common type of brushed DC motor  used in servo applications. Figure6:brushed or brushless Servo Motor  Brushless DC motors replace the physical brushes and commutator with an electronic commutation method, typically using Hall effect sensors or an encoder. Figure7:brushed or brushless Servo Motor  AC motors are generally brushless, though some designs do have brushes and are mechanically commutated, such as the universal motor, which can run on either AC or DC power. Figure8:brushed or brushless Servo Motor      3.3 Synchronous or Asynchronous While DC motor  s are generally classified as brushed or brushless, AC motors  are often distinguished by the rotational speed of their synchronous or asynchronous field. If we recall from the AC-DC discussion, the frequency of the supply voltage and the number of magnetic poles determine the speed of an AC motor. This speed is known as the synchronous speed. As a result, in a synchronous motor, the rotor rotates at the same rate as the rotating magnetic field of the stator. Figure9:synchronous or asynchronous Servo Motor  In an asynchronous motor, also known as an induction motor, the rotor rotates at a slower rate than the stator's rotating magnetic field. However, the speed of an asynchronous motor can be varied using a variety of control methods, including changing the number of poles and changing the frequency, to name a few. Figure10:synchronous or asynchronous Servo Motor      Ⅳ Servo Motor Working Principle A servo is made up of a motor (either DC or AC), a potentiometer, a gear assembly, and a control circuit. First and foremost, we use gear assembly to reduce RPM and increase motor torque. Assume that at the initial position of the servo motor shaft, the position of the potentiometer knob is such that no electrical signal is generated at the potentiometer's output port. An electrical signal is now applied to the error detector amplifier's other input terminal. The difference between these two signals, one from the potentiometer and one from other sources, will now be processed in a feedback mechanism and output will be provided in the form of an error signal. This error signal serves as the motor's input, and the motor begins to rotate. The motor shaft is now connected to the potentiometer, and as the motor rotates, so does the potentiometer, generating a signal. As a result, as the potentiometer's angular position changes, so does its output feedback signal. After a while, the position of the potentiometer reaches a point where the output of the potentiometer is the same as the external signal provided. There will be no output signal from the amplifier to the motor input because there is no difference between the externally applied signal and the signal generated at the potentiometer in this condition, and the motor will stop rotating. Figure11:synchronous or asynchronous Servo Motor    Ⅴ Applications of Servo Motors Servo Motors are used in a variety of applications, some of which are listed below:In robotics, the servo motor is used to activate movements, giving the arm its precise angle.The servo motor is used to start, move, and stop conveyor belts that transport the product through multiple stages. As an example, consider product labeling, bottling, and packaging.The servo motor is built into the camera to correct a lens and improve out-of-focus images.In a robotic vehicle, the servo motor is used to control the robot wheels, producing enough torque to move, start, and stop the vehicle as well as control its speed.In a solar tracking system, the servo motor is used to correct the angle of the panel so that each solar panel faces the sun.The servo motor is used in metal forming and cutting machines to provide milling machines with precise motion control.Textiles use servo motors to control spinning and weaving machines, knitting machines, and looms.The Servo motor is used in automatic door openers in public places such as supermarkets, hospitals, and theaters to control the door.   Ⅵ Difference Between Stepper Motor and Servo Motor  Comparison Chart Basis for ComparisonStepper MotorServo MotorBasicStepper motor operates in steps.It is continuous operating machine.System configurationOpen loopClosed loopPower requirementMoreComparatively lessDesignSimpleComplexAbility to responseHighComparatively lowCostInexpensiveExpensiveReliabilityMoreLessNoise and vibrationHighComparatively lessOperating speedSlowFastFeedback mechanismNot existExistHeat generationMoreComparatively lessNumber of polesGenerally 50 to 150Around 4 to 12Life spanMoreLessDamage due to overloadLess prone to get damaged.Comparatively more prone to get damaged.Torque producedHighLowEfficiencyLessMoreTolerance towards moment of inertiaHighLowApplicationsIn gaming, textile, welding machineries, medical and 3D printing equipments, etc.In robotics, antenna positioning systems, automatic doors, cameras, remote controlled equipments, etc. Ⅶ Servo Motors Control with an Arduino  You can connect small servo motors directly to an Arduino  to control the shaft position very precisely. Most servo motors have the following three connections: Black/Brown ground wire.Red power wire (around 5V).Yellow or White PWM wire. In this experiment, the power and ground pins will be connected directly to the Arduino  5V and GND pins. The PWM input will be connected to a digital output pin on the Arduino,  7.1 Experiment 1 Hardware Required1 x TowerPro SG90 servo motor1 x Arduino  Mega25603 x jumper wires   Wiring Diagram The best thing about servo motors is that they can be directly connected to an  Arduino ,  Connect the motor to the Arduino  in the manner shown in the table below: Servo red wire – 5V pin Arduino          Servo brown wire – Ground pin Arduino          Servo yellow wire – PWM(9) pin Arduino  Caution: Do not try to rotate the servo motor by hand, as you may damage the motor.     Figure12: Wiring Diagram Code When the program starts, the servo motor will slowly rotate from 0 to 180 degrees, one degree at a time. When the motor has rotated 180 degrees, it will start rotating in the opposite direction until it reaches the home position. #include //Servo library Servo servo_test; //initialize a servo object for the connected servo int angle = 0; void setup() { servo_test.attach(9); // attach the signal pin of servo to pin9 of arduino} void loop() { for(angle = 0; angle < 180; angle += 1) // command to move from 0 degrees to 180 degrees { servo_test.write(angle); //command to rotate the servo to the specified angle delay(15); } delay(1000); for(angle = 180; angle>=1; angle-=5) // command to move from 180 degrees to 0 degrees { servo_test.write(angle); //command to rotate the servo to the specified angle delay(5); } delay(1000);} Ⅷ Control with  Raspberry Pi In this tutorial, we will use the Raspberry Pi  to control a servo motor. Before we get to the servo, let's talk about PWM because it's the basis for controlling a servo motor.   8.1 PWM (Pulse Width Modulation) PWM is an abbreviation for 'Pulse Width Modulation.' PWM is a technique for obtaining variable voltage from a steady power supply. Consider the circuit below to better understand PWM.   Figure13:PWM   In the figure above, if the switch is closed continuously for a period of time, the LED will be 'ON' during that time. If the switch is closed for half a second and then opened for the next half a second, the LED will be turned on only for the first half a second. The percentage of time the LED is on over the total time is known as the  Duty Cycle , and it can be calculated as follows:   Duty Cycle =Turn ON time/ (Turn ON time + Turn OFF time) Duty Cycle = (0.5/ (0.5+0.5)) = 50% As a result, the average output voltage will be 50% of the battery voltage. When we increase the ON and OFF speed to a certain level, the LED will dim instead of being ON and OFF. This is because our eyes cannot clearly detect frequencies higher than 25Hz. Consider a 100ms cycle with an LED that is off for 30msec and on for 70msec. We will have 70% stable voltage at the output, so the LED will glow continuously at 70% intensity. The Duty Ratio ranges from 0 to 100. '0' denotes complete inactivity, while '100' denotes complete activation. This Duty Ratio is critical for Servo Motor,  This Duty Ratio determines the position of the Servo Motor,    8.2 Components Required We're running Raspbian Jessie on a Raspberry Pi  2 Model B. All of the basic hardware and software requirements have already been discussed, and you can find them in the Raspberry Pi  Introduction; however, we will need: Connecting pins 1000uF capacitor SG90  Servo Motor  Breadboard   8.3 Circuit Diagram Figure14:Circuit Diagram If A1000F is not connected across the +5V power rail, the  PI  may shut down unexpectedly while controlling the servo.   8.4 Working and Programming Explanation Once everything is connected according to the circuit diagram, we can power on the  PI and begin writing the program in PYHTON. We will go over a few commands that we will use in the PYHTON program. We will import a GPIO file from the library, and the function below will allow us to program the GPIO pins on the PI. We're also renaming "GPIO" to "IO," so in the program, whenever we refer to GPIO pins, we'll say "IO." import RPi.GPIO  as IO When the GPIO pins that we are attempting to use are performing other functions. In that case, we'll get warnings while running the program. The following command instructs the PI to disregard the warnings and continue with the program. IO.setwarnings(False) We can refer to the GPIO pins of the PI by either their pin number on the board or their function number. On the board, for example, 'PIN 29' is 'GPIO5'. So we specify whether we want to represent the pin here by '29' or '5'. IO.setmode (IO.BCM) PIN39 or GPIO19 is selected as the output pin. This pin will provide PWM output. IO.setup(19,IO.OUT) After we have set the output pin, we must configure it as a PWM output pin. p equals IO. Power-Wave Modulation (PWM) (output channel, frequency of PWM signal) The above command is for configuring the channel as well as the frequency of the channel." 'p' is a variable that could be anything. We'll use GPIO19 as the PWM "Output channel," and the "Frequency of PWM signal" will be 50, because the SG90's working frequency is 50Hz. The command below is used to initiate PWM signal generation. 'DUTY CYCLE' is used to specify the 'Turn On' ratio, as previously explained. p.start(DUTYCYCLE) The following command is used to create a forever loop, which means that the statements inside the loop will be executed indefinitely.   8.5 Code import RPi.GPIO  as IO        # calling for header file for GPIO’s of PI import time                           # calling for time to provide delays in program IO.setwarnings(False)          # do not show any warnings IO.setmode (IO.BCM)            # programming the GPIO by BCM pin numbers. (like PIN29 as‘GPIO5’) IO.setup(19,IO.OUT)             # initialize GPIO19 as an output p = IO.PWM  (19,50)              # GPIO19 as PWM output, with 50Hz frequency p.start(7.5)                             # generate PWM signal with 7.5% duty cycle while 1:                                                       # execute loop forever                                             p.ChangeDutyCycle(7.5)                   # change duty cycle for getting the servo position to 90º         time.sleep(1)                                      # sleep for 1 second         p.ChangeDutyCycle(12.5)                  # change duty cycle for getting the servo position to 180º         time.sleep(1)                                     # sleep for 1 second         p.ChangeDutyCycle(2.5)                  # change duty cycle for getting the servo position to 0º         time.sleep(1)                                     # sleep for 1 second   Ⅸ FAQ 1. Are servo motors AC or DC? AC servo motors depend on an AC power source whereas DC Servo motors depend on DC power source (like Batteries). AC servo motors performance is dependent upon voltage as well as frequency whereas DC servo motors performance mainly relies upon voltage alone. 2. Can servo motors rotate 360? The position of the servo motor is set by the length of a pulse. ... The end points of the servo can vary and many servos only turn through about 170 degrees. You can also buy 'continuous' servos that can rotate through the full 360 degrees. 3. Which motor is used in servo motor? While the majority of motors used in servo systems are AC brushless designs, brushed permanent magnet motors are sometimes employed as servo motors for their simplicity and low cost. The most common type of brushed DC motor used in servo applications is the permanent magnet DC motor.

Introduction In the FOC(Field Oriented Control) algorithm, the sampling current is the basis of the algorithm implementation and a very important part. So accurate current sampling can bring better result to the algorithm. In other words, if the current sampling is accurate, it will be very helpful for the subsequent coordinate transformation to obtain required results. From this we can see the role of current sampling in the entire FOC algorithm. Understanding Field-Oriented Control Catalog Introduction Ⅰ Current Sampling Method Ⅱ Three Sampling Methods and Precautions 2.1 Single-resistor Sampling 2.2 Dual-resistor Sampling 2.3 Triple-resistor Sampling Ⅲ The Key to Sampling Ⅳ Delay Source Ⅴ Delay Type and Typical Time Ⅵ Analysis in Details 6.1 PWM Dead Time Insertion 6.2 Optocoupler Delay and Pre-Driver Delay 6.3 Transistor Switching Delay 6.4 Other Delays Ⅶ FAQ Ⅰ Current Sampling Method In motor control, the current sampling method is generally to use PWM to trigger ADC to convert. Taking SoC(System-on-a-Chip) as an example, the ADC module will be configured to automatically sample and trigger conversion. When the trigger point set by the PWM module matches, the signal will be given to the ADC module. At this time, the sampling switch in circuit will be disconnected, and then the ADC module will start to convert, and the voltage of the corresponding sampling current can be obtained after the conversion is completed. The AD value of the signal, you can use this value in the program to write and verify the algorithm. Figure 1. Current Sampling Time Ⅱ Three Sampling Methods and Precautions Current sampling is the basis of FOC, including current sensor sampling and resistor sampling. Resistor sampling is widely used for its simple and low-cost characteristics. The method includes single-resistor sampling, dual-resistor sampling, and triple-resistor sampling. 2.1 Single-resistor Sampling The biggest difference between the single-resistor and the other two methods is that it cannot obtain two current signals at the same time. Even if two current signals are obtained, there is an error in estimating the third current signal. The formula Iu+Iv+Iw=0 is conditional, that is, the three currents must be recorded at the same time. When the inductance of the motor is larger, the two currents obtained are closer to the real situation. When the inductance is small, the deviation may be relatively large. So if the inductance of the current is large, single-resistor sampling can be selected.This method requires two samplings in one PWM cycle. In this case, it is necessary to analyze the switch state in the algorithm to clarify which phase current the reconstructed current corresponds to at the time of sampling. 2.2 Dual-resistor Sampling In the case of dual-resistor sampling, the sampled two-phase current must be used directly. Even if there is a deviation, it needs to be used. This method cannot be used to calculate the third-phase current based on the other two-phase sampling like the triple-resistor sampling. That is to say, this method needs to consider the problem of the sampling window. If the sampling current is to be guaranteed to be accurate, the sampling window must be large enough. To make the sampling window large enough, the PWM waveform needs to be deformed. But this will increase the execution time of the algorithm. The advantage of this approach is to reduce a current-sense resistor and an op amp.As shown in the figure below, the front of the red circle is the oscillating area. If the sampling window is small, only the oscillating area will not be able to obtain an accurate current. To process the sampling window, you can refer to the following figure, so that the obtained current will be more accurate. Figure 2. Current Sampling Zone 2.3 Triple-resistor Sampling This method is the simpler among the three methods. It directly uses three current-sensing resistors to sample the three-phase phase current of the motor, and the result obtained in this way is relatively straightforward. Using the formula Iu+Iv+Iw=0, recalculate the phase current of one phase with a small sampling window. So that the accuracy of the result obtained is the highest, and the implementation of the following related algorithms is easier. It is the advantage of this method. However, three current-sense resistors and three op amps are used, the hardware cost will be higher than the other two.   Ⅲ The Key to Sampling The current sampling includes peak current and average current sampling. Generally, the most common is the average current sampling and its control, so there are actually two ways to sample the average current. One is that the current-sense resistor is placed on the upper bridge of the inverter bridge. The other is that the current-sense resistor of the inverter bridge is connected to the lower end of the lower bridge.The general method is the latter. The current detection circuit corresponding to this method is relatively simple, and the corresponding power consumption will also be reduced. In this case, the freewheeling current is collected at the lower end, and then we can sample at the midpoint of the lower bridge opening. At this time, the corresponding current reflects the average current, so the corresponding current control is the average.Then, if we use the three-resistor sampling method, the selected ADC module must have at least the function of simultaneous sampling of three channels. So as to ensure that the three-phase currents obtained by sampling are the currents at the same time, and at this time, to meet the condition, Iu+ Iv+Iw=0.In the case of dual-resistor sampling, there are only two sampling resistors, and the obtained current cannot use the formula Iu+Iv+Iw=0. Therefore, even if the sampling window is small, if the algorithm is not processed, the double-resistor scheme has limitations. In order to get a better adaptation to the scene, algorithm compensation must be performed on the dual-resistor method, which is also the key point of it.Similarly, for the single-resistor sampling way, the corresponding current needs to be obtained according to different switch combinations, and it needs to be sampled twice in a PWM cycle. This method cannot satisfy Iu+Iv+Iw=0, and can only be determined by an algorithm. Compensation and correction are performed, so the single-resistor method is more difficult to take. However, if the difficulty can be solved, this method is the best and cheapest one.   Ⅳ Delay Source During the development of the motor-driven FOC control, have you encountered the situation that the motor is too noisy, inefficient or even unable to operate? All of this may be due to sampling anomalies of the phase currents, resulting in the inability to reconstruct the correct three-phase currents in the FOC algorithm. Here is an analysis of a factor that affects current sampling: the delay source.In the motor drive FOC control of double-resistor sampling, the sampling point is set as the middle moment when the lower tube of the drive bridge is turned on. Note that this is the middle moment when the lower tube of the drive bridge is turned on, not the middle moment of the PWM cycle output by the MCU. There are as many as seven delay sources in this typical drive topology because the PWM is calculated from the MCU to the ADC module where the current signal is sent to the MCU. Figure 3. MCU Output Ⅴ Delay Type and Typical Time The table below details the seven sources of delay that exist in motor drive system topologies and their typical timings. These delays will be superimposed together, and the effect is that the actual output PWM waveform lags behind the PWM waveform that the MCU calculates the expected output. According to this calculation, the phase current sampling point needs to lag the middle moment of the MCU calculating the expected output PWM waveform. Delay Type Typical Time PWM Dead Time Insertion 100ns-2μs Optocoupler Isolation to Pre-driver 40ns-300ns Pre-driver Switch Delay About 50ns MOSFET Switching Time 100ns-1μs Amplifier Delay <1μs Low-pass Filter Delay 1-2μs ADC Delay 50ns-200ns   Ⅵ Analysis in Details 6.1 PWM Dead Time Insertion In the three-phase brushless motor drive system, three bridge arms are required to control the current flow of the phase line, and there are two power devices on each bridge arm, such as MOSFET and IGBT. The pair of power devices cannot be turned on at the same time, otherwise a short circuit will occur. Here MOSFET is used as a power device to illustrate. In the control, dead time must be inserted to ensure that the upper and lower MOSFETs are not turned on at the same time. Typical values of dead time may be between 100ns and 2μs, depending on various factors in the system, such as MOSFET drive voltage and type.After the required PWM waveform is inserted into the dead time, what you get is that both the PWM midpoint and the rising edge are shifted to the right. When using the FOC control algorithm calculates the proper PWM, we start seeing the first delay, recording the dead time. Figure 4. Dead Time Insertion 6.2 Optocoupler Delay and Pre-Driver Delay The signal response of the various optocouplers and pre-drivers causes additional delays between the moment the MCU controls the FTM module to output the PWM waveform and the moment the MOSFET gate is controlled. The output of the pre-driver is delayed by a period of time (Delay1) compared to the waveform output from the MCU pins. Figure 5. Delay 1 6.3 Transistor Switching Delay Through the pre-driver, the PWM waveform reaches the MOSFET transistors, but due to their inherent characteristics, all transistors take a certain amount of time to turn on and off. This delay time varies depending on the transistor type and the voltage level required to switch between on/off. Delay 2 is the total delay between the theoretical switching point (CMP2) of the phase line voltage and the instant of the actual switching point. Figure 6. Delay 2 Finally, the gate voltage reaches the level that can make the transistor turn on, the current passes through the phase line and the sampling resistor, and a voltage difference is generated across the sampling resistor. The red waveform is the phase current waveform in an ideal state. At this time, there is a total delay time between the midpoint of the PWM cycle calculated and generated by the MCU, and the "phase current midpoint shift" is shown in the figure. Figure 7. Phase Current Midpoint Shift 6.4 Other Delays As shown in the figure below, the final delay chain that affects the current sampling is formed by the amplifier slew rate, the low-pass filter on the MCU pins, and the ADC slew rate. The time marked by the red circle in the figure is the correct current sampling time. It can be seen that the phase current sampling point is greatly delayed compared with the PWM midpoint output by the FTM. Figure 8. Other Delay In all and electrical and electronic circuits, there will be signal delay problems. And it is impossible to completely eliminate them, but the impact can be reduced by selecting low-delay devices. In the motor drive, in addition to selecting the appropriate device, it is also necessary to perform software compensation for the signal delay. The precise delay time of these delay sources mentioned in the article can be obtained by oscilloscope and calculation, and the correct current sampling time can be obtained by compensating for these delays in software. In this way, the data collected at the correct moment can be used as the data source for reconstructing the three-phase current of the motor in the FOC control.   Ⅶ FAQ 1. What is FOC algorithm?Field-oriented control (FOC), or vector control, is a technique for variable frequency control of the stator in a three phase AC induction motor. 2. What is FOC drive?Vector control, also called field-oriented control (FOC), is a variable-frequency drive (VFD) control method in which the stator currents of a three-phase AC or brushless DC electric motor are identified as two orthogonal components that can be visualized with a vector. 3. What is FOC brushless motor?FOC implementation allows the BLDC motor to run more efficiently (high power factor and better light load efficiency), more smoothly (lower torque ripples) with quick dynamic response (better dynamic performance to load and speed changes). 4. What is FOC in BLDC motor?Field oriented control (FOC) is an important control approach for Brushless DC motors. It resembles sinusoidal commutation but adds a major mathematical twist. Figure 3a shows control schemes for both sinusoidal commutation and field oriented control. 5. How is Bldc phase current measured?With a BLDC motor use an ac voltmeter to measure the voltage between any 2 wires of the 3 motor wires and then convert the line-to-line voltage to the phase voltage value by dividing the line-to-line voltage by 3 =1.73. 6. Do BLDC motors have inrush current?Handle Peak Inrush Current of a BLDC Motor to protect the Power Supply. Summary: BLDC motors have a Peak current on startup which is 3x or more the rated current. The motor has a rated current of 7.3A. 7. What causes motor inrush current?When an electrical device, such as an AC induction motor, is switched on, it experiences a very high, momentary surge of current, referred to as inrush current. ...The interaction of these two magnetic fields produces torque and causes the motor to turn.

Ⅰ Introduction In this project, we will use hardware ultrasonic sensor and  Raspberry Pi 3, Software Python code. Not everyone is familiar with ultrasonic sensor and Raspberry Pi3. Therefore, in the front part ,we will introduce some basic knowledge about ultrasonic sensor and Raspberry Pi3. This is conducive to understanding the project better. And then, we will have a look at the project of wiring Ultrasonic Sensor  (HC-SR04) with Raspberry Pi3 Catalog Ⅰ Introduction Ⅱ Ultrasonic Sensor Related Video Ⅲ Basic Guide to Ultrasonic Sensor  3.1 What is an ultrasonic sensor? 3.2 How Ultrasonic Sensors Work？ 3.3 Using Multiple Sensors & Avoiding Disruption 3.4 How are Ultrasonic Sensors Used? Ⅳ Basic Guide to Raspberry Pi3 4.1 What is  Raspberry Pi3? 4.2 What Is the Raspberry Pi3 Capable of？ 4.3 How do I Get Started With the Raspberry Pi 3? 4.4 How Is the Raspberry Pi 3 Different From Its Predecessors? Ⅴ Ultrasonic Sensor (HC-SR04) + Raspberry Pi3 5.1 Hardware 5.2 Wire Setup 5.3  Breadboard  5.4 Software Ⅵ FAQ     Ⅱ Ultrasonic Sensor Related Video   Ultrasonic Sensor Video Description: Connecting the Ultrasonic Sensor( HC-SR04) to the Raspberry Pi to measure distance. Equipment you need One 1 kilo-Ohm resistor One 2 kilo-Ohm resistor 8 Female-Male Jumper Wire   Ⅲ Basic Guide to Ultrasonic Sensor  3.1 What is an ultrasonic sensor? An ultrasonic sensor is a device that uses ultrasonic sound waves  to determine the distance between two objects. An ultrasonic sensor employs a transducer to send and receive ultrasonic pulses that relay information about the proximity of an object. High-frequency sound waves  reflect off boundaries, resulting in distinct echo patterns. Fihure1: Ultrasonic Sensor   3.2 How Ultrasonic Sensors Work？ Ultrasonic sensors  operate by emitting a sound wave at a frequency  that is above the range of human hearing. To receive and transmit an ultrasonic sound, the sensor's transducer functions as a microphone. Like many others, our ultrasonic sensors  use a single transducer to send a pulse and receive the echo. The sensor calculates the distance to a target by measuring the time elapsed between sending and receiving the ultrasonic pulse. Figure2:How Ultrasonic Sensors Work This module's operation is straightforward. It emits a 40kHz ultrasonic pulse that travels through the air and, if it encounters an obstacle or object, bounces back to the sensor. The distance can be calculated by multiplying the travel time by the speed of sound. Ultrasonic sensors  are an excellent solution for detecting clear objects. Because of target translucence, applications that use infrared sensors.  for example, struggle with this particular use case for liquid level measurement. Ultrasonic sensors  detect objects regardless of color, surface, or material for presence detection (unless the material is very soft like wool, as it would absorb sound.) Ultrasonic sensors  are a reliable choice for detecting transparent and other items where optical technologies may fail.   3.3 Using Multiple Sensors & Avoiding Disruption When putting multiple sensors  into an application, it's critical to connect them in a way that prevents crosstalk and other interference. To prevent the ultrasonic signals from your sensor from being disrupted, keep the face of the ultrasonic transducer clear of any obstructions. Common obstructions include: DirtSnowIceOther Condensation We recommend our Self Cleaning sensors  for this application. Our self-cleaning function is designed to run continuously for the self-cleaning feature to be active. They are intended specifically for applications requiring condensation resistance in high moisture environments. Please keep in mind that the Self Cleaning function is not intended to remove dirt from the transducer's surface. Its purpose is to clear the transducer's face of moisture so that it can operate normally.   3.4 How are Ultrasonic Sensors Used? Our ultrasonic distance, level, and proximity sensors  are frequently used in conjunction with microcontroller platforms such as Raspberry Pi,  ARM , PIC,  Arduino , Beagle Board, and others. Ultrasonic sensors send sound waves  toward a target and measure the time it takes for the reflected waves to return to the receiver to determine their distance. This sensor is an electronic device that transmits ultrasonic sound waves  to measure the distance to a target and then converts the reflected sound into an electrical signal. Our sensors are frequently used as proximity detectors. Ultrasonic sensors are also used in obstacle detection systems and in manufacturing. Our ShortRange sensors provide the option for closer range detection in situations where a sensor that ranges objects as close to 2cm is required. These are also designed with very low power requirements in mind, as well as environments requiring noise rejection.   Ⅳ Basic Guide to Raspberry Pi3 4.1 What is  Raspberry Pi3? The  Raspberry Pi 3 Model B is the most recent model of the $35 Raspberry Pi computer. The Pi isn't your typical machine; in its most basic form, it lacks a case and is simply a credit-card-sized electronic board, similar to those found inside a PC or laptop but much smaller.   4.2 What Is the Raspberry Pi3 Capable of？ Surprisingly large. For starters, the Pi 3 can be used as a low-cost desktop, media center, retro gaming console, or router, as shown below. That, however, is only the tip of the iceberg. There are hundreds of projects where people have used the Raspberry Pi to build tablets, laptops, phones, robots, smart mirrors, take pictures on the edge of space, and run experiments on the International Space Station.   Figure3:The Raspberry Pi 3.   4.3 How do I Get Started With the Raspberry Pi 3? One thing to keep in mind is that the Pi is merely a bare board. You'll also need a power supply, a monitor or TV,  HDMI  cables to connect to the monitor, and a mouse and keyboard. After connecting all of the cables, the simplest way for new users to get up and running on the Pi is to download the NOOBS (New Out-Of-Box Software) installer. Once the download is complete, follow the instructions to learn how to install an operating system on the Raspberry Pi. The installer makes it simple to install various operating systems, though the official OS Raspbian is a good choice for first-time users—other operating systems are listed below. Raspbian's appearance and feel should be familiar to any desktop computer user. The operating system, which is constantly being updated, recently received a graphical makeover and now includes an optimized web browser, an office suite, programming tools, educational games, and other software.   4.4 How Is the Raspberry Pi 3 Different From Its Predecessors? The Raspberry Pi 3 quad-core processor is both faster and more capable than its predecessor, the Raspberry Pi 2. For those interested in benchmarks, the Pi 3's CPU—the board's main processor—outperforms the Pi 2 by roughly 50-60% in 32-bit mode, and is 10x faster than the original single-core Raspberry Pi (based on a multi-threaded CPU benchmark in SysBench). Real-world applications will see performance increases ranging from 2.5x for single-threaded applications to more than 20x when video playback is accelerated by the chip's NEON engine when compared to the original Pi. Unlike its predecessor, the new board can play 1080p MP4 video at 60 frames per second (with a bitrate of around 5400Kbps), further enhancing the Pi's media center credentials. That's not to say that all videos will playback this smoothly; performance will vary depending on the source video, the player used, and the bitrate. With built-in Wi-Fi and Bluetooth, the Pi 3 also supports wireless internet right out of the box. The most recent board can also boot directly from a USB-attached hard drive or a pen drive, as well as from a network-attached file system via PXE, which is useful for remotely updating a Pi and sharing an operating system image between multiple machines.   Ⅴ Ultrasonic Sensor (HC-SR04) + Raspberry Pi3 A distance measurement is required or advantageous for many (outdoor) projects. These small modules, which start at 1-2 dollars and can measure distances of up to 4-5 meters using ultrasound, are surprisingly accurate. The connection and control are demonstrated in this tutorial. 5.1 Hardware Raspberry pi 3Ultrasonic Sensor(s) - HC-SR04A set of resistors for each sensor you are connecting330Ω and 470ΩJumper wires to connect the sensor(s) to the piBreadboard to connect the sensor(s) to the pi   5.2 Wire Setup Pins The sensor has four (labeled) pins that must be connected to the Raspberry Pi's pins. Pin 2 to VCC (5v - power)Pin 6 to GND (ground)Pin 12 receives a TRIG signal (GPIO18) The ECHO resistor 330 - Attach it to Pin 18 at one end (GPIO24) - Connect it to Pin6 as well, using a 470 resistor (ground). - This is done because GPIO pins can only withstand a maximum voltage of 3.3V.   5.3  Breadboard  As shown in the circuit diagram, connect the sensor to the pi using a breadboard. By replicating this exact setup on the other half of the breadboard, an additional sensor can be connected to the pi. Connect the VCC and GND pins together (2 and 6) For the TRIG and ECHO connections, use any two GPIO pins. Just make sure to include the correct GPIO pins in your code. Figure4: Connecting resistors and jumper wires between sensors and pi       5.4 Software Python Create a new script Figure5:Creating a new script in Python 3 Choose Menu → Programming → Click on Python 3 to create a new scriptWhen you run the code, the script below will print the distance of the object in front of the sensor.Because this code is easily manipulated to add another sensor, all variables have a "1" after them.Simply copy and paste each section of code, renaming variables with a "2."Make sure to connect a TRIG2 and an ECHO2 to the pi's two new GPIO Pins and to mirror the circuit diagram on the other half of the breadboard. import  RPi.GPIO  as GPIO import time GPIO.setmode(GPIO.BCM) TRIG1 = 18 ECHO1 = 24 #print ("Distance Measurement In Process") GPIO.setup(TRIG1, GPIO.OUT) GPIO.output(TRIG1, False) GPIO.setup(ECHO1, GPIO.IN) #print ("Waiting For Sensor1 To Settle") time.sleep(.1) GPIO.output(TRIG1, True) time.sleep(0.00001) GPIO.output(TRIG1, False) while GPIO.input(ECHO1) == 0:     pass     pulse_start1 = time.time() while GPIO.input(ECHO1) == 1:     pass     pulse_end1 = time.time() pulse_duration1 = pulse_end1 - pulse_start1 distance1 = pulse_duration1 * 17150 distance1= round(distance1, 2) print ("Distance1:",distance1, "cm") time.sleep(10) GPIO.cleanup()   Make a copy of your script and save it as ultrasonic distance.py. Go to File and click on Save as In the Save in field, navigate to the C: drive and then select a folder to save in. In the File name field, enter ultrasonic distance.py. Select All Files in the Save as type field. Click the Save button. To run the script, use the terminal. Clicking on the monitor icon at the top of the screen will launch the terminal. Enter cd "folder name" to change directory to your pythonpractice folder, then enter ultrasonic distance.py to run your program. Ⅵ FAQ 1. Does HC-SR04 need resistor? If you are using the ultrasonic transmitter from a HC-SR04 , I think you will find it needs between 5 and 12V to drive it. So you don't need a resistor you actually need a transistor circuit to provide the greater voltage under the control of the gpio. 2. What is the range of HC SR04? 2 cm to 400 cm The HC-SR04 ultrasonic sensor uses SONAR to determine the distance of an object just like the bats do. It offers excellent non-contact range detection with high accuracy and stable readings in an easy-to-use package from 2 cm to 400 cm or 1” to 13 feet. 3. Is ultrasonic sensor digital or analog? The output of the Ultrasonic Sensor is digital. Two of the four pins are forsupplying power to it, one is for sending an echo signature to it, and the other is for getting output from it. 4. What is ultrasonic sensor HC-SR04? The HC-SR04 Ultrasonic Distance Sensor is a sensor used for detecting the distance to an object using sonar. ... The HC-SR04 uses non-contact ultrasound sonar to measure the distance to an object, and consists of two ultrasonic transmitters (basically speakers), a receiver, and a control circuit. 5. What are the types of ultrasonic sensor? All together there are four types of ultrasonic sensors, classified by frequency and shape: the drip-proof type, high-frequency type, and open structure type (lead type and SMD type). 6. Is HC SR04 analog or digital? One of them is digital and the other is analog. We choose to use two sensors that measure: The UltraSonic Sensor (HC-SR04): Digital Sensor.

Introduction As a power semiconductor device, IGBT(insulated-gate bipolar transistor) is widely used in the fields of rail transit, smart grid, industrial energy saving, electric vehicles and new energy equipment. It has the characteristics of energy saving, convenient installation and easy maintenance, and stable heat dissipation. It is the core device for energy conversion and transmission. A brief overview, IGBT can be said to be a combination of MOSFET(metal–oxide–semiconductor field-effect transistor) and BJT(bipolar junction transistor). That is, it combines the gate voltage control transistor (high input impedance) of the MOSFET, and uses the dual carriers of the BJT to achieve the purpose of large current (voltage-controlled bipolar device). So what is the internal structure of such a combination? This article will explain in detail with examples. What is IGBT and Its Applications Catalog Introduction Ⅰ IGBT Module Explained Ⅱ IGBT Internal Structure Ⅲ IGBT Internal Current Flow Ⅳ How to Disassemble IGBT Module? Ⅴ FAQ Ⅰ IGBT Module Explained The model of the IGBT module to be disassembled as an example is: FF1400R17IP4. The appearance and equivalent circuit of the module are shown in Figure 1. The length, width and height of this module are: 25cmx8.9cmx3.8cm. The module contains two IGBTs, which are what we often call half-bridge modules. The rated voltage and current of each IGBT are 1.7kV and 1.4kA. Figure 1. FF1400R17IP4 Part 8, 9, 10, 11, and 12 are power terminals and need to be connected to a power circuit.1, 2, 3, 4, and 5 are auxiliary control terminals, which need to be connected to the gate drive circuit.6 and 7 are NTC thermistors, used for temperature detection or over-temperature protection.After having a general understanding of its structure, what can we do with such a black module with this structure? Take an example around us: new electric vehicles, everyone should be familiar with it. Three such black modules can be used as a three-phase motor driver. If it is equipped with a battery, it can drive an electric bus. Of course, this module is also used in many other applications. Figure 2. IGBT in Electric Bus   Ⅱ IGBT Internal Structure After having a preliminary understanding of the external structure and application of the IGBT module, let us enter the subject of this article to see what the inside of this high-tech black module looks like. Figure 3 is the internal picture of the IGBT module with the black casing removed. It should be noted that the most common copper and aluminum are inside the IGBT module. Figure 3. IGBT Internal Structure Figure 4 is a cross-sectional view of the IGBT module. If the black casing and external connection terminals are removed, the IGBT module mainly contains 3 components, the heat dissipation substrate, the DBC substrate and the silicon chip (including the IGBT chip and the Diode chip), and the rest is mainly solder layers and interconnecting wires are used to connect IGBT chips, Diode chips, power terminals, control terminals and DBC(Direct Bond Copper). Below we will briefly introduce each part. Figure 4. IGBT Section View ① Heat Sink SubstrateThe bottom of the IGBT module is the heat dissipation substrate, the main purpose is to quickly transfer the heat generated by the IGBT switching process. Since copper has better thermal conductivity, the substrate is usually made of copper, and the thickness of it is 3-8mm. Of course, there are also substrates made of other materials, such as aluminum silicon carbide (AlSiC), both of which have their own advantages and disadvantages. ② DBCDBC (Direct Bond Copper) is a ceramic surface metallization technology, which contains 3 layers. Have a ceramic insulating layer in the middle and a copper clad layer above and below respectively, as shown in Figure 5(a). Simply put, it is to cover both sides of an insulating material with a copper layer, and then etch a pattern that can carry current on the front side, and the back side must be directly soldered to the heat sink substrate. Figure 5. BDC Base vs PCB The main function of DBC needs to ensure the electrical insulation capacity between the silicon chip and the heat dissipation substrate and good thermal conductivity, while also providing a certain current transmission capacity. The DBC substrate is similar to a 2-layer PCB circuit board. The insulating material in the middle of the PCB is generally FR4, while the commonly used ceramic insulating materials for DBC are aluminum oxide (Al2O3) and aluminum nitride (AlN).For the IGBT module analyzed in this article, there are 6 DBCs inside, and each has 4 IGBT chips and 2 Diode chips. Among them, 2 IGBT chips and 1 Diode chip are used as the upper tube, and the rest are used as the lower tube. As shown in Figure 6. Figure 6. DBC Diagram and Equivalent Circuit ③ IGBT ChipThe IGBT chip model used inside the module is: IGCT136T170. The manual can be downloaded from Infineon official website. Figure 7 shows the top view and basic parameters of the IGBT chip. The gate and emitter of the IGBT are above the chip (front side), and the collector is below (back side). The thickness of the chip is 200um. After the IGBT powers on, the current flows from bottom to top, so the IGBT of this structure can also be called a vertical device. Chip Type VCE ICn1) Die Size IGC136T170S8RH2 1700A 117.5A 17.72×7.7mm2 Figure 7. IGBT Chip Diagram If you make a vertical cut on the 200um chip, you can get the internal structure shown in Figure 8, which is a combination of P-type or N-type semiconductors with different doping. Figure 8 shows the well-known equivalent circuit of an IGBT, which is usually understood as a MOS-controlled PNP transistor. When start to learn about power electronics, you may feel that this picture is a bit strange. Why not draw the collector on the top and the emitter on the bottom? Until you understand that the IGBT current flows from bottom to top, it is not difficult to explain. Figure 8. IGBT Chip Structure and Equivalent Circuit Let’s have a general understanding of the electrical parameters of this IGBT chip. This chip can pass a DC current of 117.5A at 100°C. It can be seen from Figure 4 that a single IGBT device inside the module contains a total of 12 IGBT chips, so the total current is: 117.5*12=1412A, which is basically the same as the 1400A rated current in the IGBT module manual.In order to ensure the current sharing effect between IGBT chips, a 11.5Ω resistor has been integrated inside the gate of each chip. At the same time, considering the current sharing between the DBCs, the two chips on each DBC share a gate resistor externally, as shown in Figure 10. When measuring it with a multimeter, and the resistance is about 4.13Ω. You can calculate it in conjunction with Figure 9 to see if it is consistent with the 1.6Ω in the IGBT module manual. Of course, you can refer to the official manual for more detailed parameters of the IGBT chip. Figure 9. IGBT Equivalent Circuit ④ Diode ChipFigure 10 is a top view of the Diode chip, with the anode on the front and the cathode on the back. The current direction of the diode is from top to bottom, which is exactly the opposite of the current direction of the IGBT. The rated current of the diode chip is 235A, and each IGBT is composed of 6 diodes in parallel, and the total current can reach 1410A, which is basically the same as the 1400A in the module manual. The thickness of diode chip is the same as IGBT, it is also 200um. For more detailed parameters of the diode chip, please refer to the official manual. Chip Type VR IFn1) Die Size SIDC130D170H 1700A 235A 16.3×8mm2 Figure 10. Diode Diagram Such a thin semiconductor material can have kV voltage and hundreds of amperes of current on and off, it’s amazing. This is why the price of high-power semiconductor devices is so very expensive.The upper copper layer interconnection of IGBT chip, Diode chip and DBC is generally realized by bonding wires. Commonly used bonding wires are aluminum wire and copper wire. Among them, the aluminum wire bonding process is mature and the cost is low, but the electrical and thermodynamic properties of the aluminum wire bonding are poor, and the expansion coefficient mismatch is large, which affects the service life of the IGBT. The copper wire bonding process has the advantages of excellent electrical and thermodynamic properties, high reliability, and is suitable for modules with high power density and efficient heat dissipation.   Ⅲ IGBT Internal Current Flow After having a basic understanding of the internal structure of the IGBT module, let us go back and interconnect all the above components to see how the current flows inside the IGBT module. Here we take the upper tube IGBT in one of the DBCs as an example to illustrate the current flow. Red represents the current direction of the upper tube IGBT (S1 and S2), and blue represents the current direction of the diode D1. Figure 11(b) is a left cross-sectional view and a schematic diagram of the current direction of the module of Figure . Figure 11(a). IGBT Current Flow Figure 11(b). IGBT Current   Ⅳ How to Disassemble IGBT Module? Some friends may be curious about how to disassemble this module, but it is actually very simple. You only need to prepare two screwdrivers and a small hammer. Figure 12. IGBT Disassemble Step 1: Unscrew the 4 screws at the bottom of the IGBT module.Step 2: Use a flat-blade screwdriver to pry open all the terminals on the front of the IGBT module. This step is very important. It is necessary to ensure that all the terminals after being pried are vertical to the module substrate.Step 3: You need to fix the IGBT in one place, or use a flat-blade screwdriver to align any position of the connection between the plastic casing of the IGBT module and the substrate, hit the screwdriver with a hammer, and pry the casing from the substrate with the screwdriver. After prying open one position, place something on it, and then pry another position, repeat that, after slowly prying open, just pry open with your hands directly.   Ⅴ FAQ 1. What is IGBT module?An IGBT is a is power semiconductor die and is the short form of insulated-gate bipolar transistor. ... An IGBT power module functions as an electronic switching device. By alternate switching direct current (DC) can be transformed to alternating current (AC) and vice versa. 2. How does IGBT module work?The IGBT combines the simple gate-drive characteristics of power MOSFETs with the high-current and low-saturation-voltage capability of bipolar transistors. The IGBT combines an isolated-gate FET for the control input and a bipolar power transistor as a switch in a single device. 3. What is the purpose of IGBT?The IGBT combines, in a single device, a control input with a MOS structure and a bipolar power transistor that acts as an output switch. IGBTs are suitable for high-voltage, high-current applications. They are designed to drive high-power applications with a low-power input. 4. How many layers are there in IGBT?Working of IGBTIGBT is constructed with 4 layers of semiconductor sandwiched together. The layer closer to the collector is the p+ substrate layer above that is the n- layer, another p layer is kept closer to the emitter and inside the p layer, we have the n+ layers. 5. Which are the terminals of IGBT?The three terminals of IGBT are Gate, Collector and Emitter. 6. How many terminals Mosfet has?four terminalsThe MOSFET has four terminals: drain, source, gate, and body or substrate. 7. What is the function of injecting layer in IGBT?The p+ substrate is also called injector layer because it injects holes into n- layer. The n- layer is called drift region. The next p layer is called the body of IGBT. The n- layer in between the p+ & p region serves to accommodate the depletion layer of pn- junction i.e. J2. 8. Can I replace IGBT with MOSFET?Due to the higher usable current density of IGBTs, it can usually handle two to three times more current than a typical MOSFET it replaces. This means that a single IGBT device can replace multiple MOSFETs in parallel operation or any of the super-large single power MOSFETs that are available today. 9. What are the three terminals of an IGBT and how does it function?The IGBT (insulated gate bipolar transistor) is a three-terminal electronic component, and these terminals are termed as emitter (E), collector(C) and gate(G). Two of its terminals namely collector and emitter are associated with a conductance path and the remaining terminal 'G' is associated with its control. 10. What is an IGBT describe its construction?IGBT – Working, Types, Structure, Operation & Applications. ... The IGBT (Insulated Gate Bipolar Transistor) takes the best parts of both BJT and MOSFET into a single transistor. It takes the input characteristics (high input impedance) of MOSFET (Insulated Gate) and the output characteristics of BJT (Bipolar nature). 11. How does IGBT convert DC to AC?The IGBT act as a switch (when a signal is applied to the gate, they turn on and then turn off when the signal is removed). By closing Q1 and Q4, a positive d.c. supply is applied to the load. Q2 and Q3 will result in a negative d.c. supply across the load. 12. What is the advantage of IGBT?The main advantages of IGBT over a Power MOSFET and a BJT are: It has a very low on-state voltage drop due to conductivity modulation and has superior on-state current density. So smaller chip size is possible and the cost can be reduced. 13. What is drift layer in IGBT?The drift region (electric field or movement of charge) of the IGBT works as a base of the PNP transistor . The current gain of the transistor depends upon the width and doping level of the transistor. 14. What is the structure of IGBT?The structure of IGBT is very much similar to that of PMOSFET, except one layer known as injection layer which is p+ unlike n+ substrate in PMOSFET. This injection layer is the key to the superior characteristics of IGBT. Other layers are called the drift and the body region. The two junctions are labeled J1 and J2. 15. What are the advantages of IGBTs?Advantages of IGBT:Simple drive circuitLow on-resistanceHigh voltage capacityFast switching speedEasy of driveLow switching lossLow on stage power dissipationLow gate drive requirement 16. Why IGBT is very popular nowadays?With its lower on-state resistance and conduction losses as well as its ability to switch high voltages at high frequencies without damage makes the Insulated Gate Bipolar Transistor ideal for driving inductive loads such as coil windings, electromagnets and DC motors. 17. Why diode is used in IGBT?We know that MOSFET or IGBT is a unidirectional device, they only conduct current in forward bias and block the current in reverse bias. ... For this reason, an external diode is connected across the MOSFET or IGBT or SCR to provide a path for reverse current.

ⅠIntroductionAs electronic technology advances, there is a greater need for high-speed PCB design. Because they can work at high speeds with integrated circuits for most electronic devices, even simple ones. Some factors and parameters have to be considered when designing a high-speed PCB. Furthermore, you will discover that the fundamental PCB design rules and methods you have mastered are exactly what you need to learn. Needless to say, it will be extremely useful to PCB designers working on high-speed PCB designs.CatalogⅠIntroductionⅡ What is High-speed PCB Design?Ⅲ High-speed PCB Related VideoⅣ When Is a Printed Circuit Board Design Considered High Speed?Ⅴ High-speed PCB Design SkillsⅥ High speed PCB  Design ConsiderationsⅦ Setup for High-Speed DesignⅧ Floorplanning a High Speed PCBⅨ How to Tell If Your Project is High SpeedⅩFAQ Ⅱ What is High-speed PCB Design?High-speed PCB design is any design in which the physical characteristics of your PCB.  such as layout, packaging, interconnection, layer stack up, and so on, begin to impact the integrity of your signals. Furthermore, when you begin designing the boards and encounter issues such as delays, crosstalk, reflections, or emissions, you will enter the world of high-speed PCB design, Because of the attention paid to these issues, high-speed design is truly unique. You may be accustomed to designing a simple PCB  where you focus primarily on component placement and routing. However, it is more important to consider some factors when using a high-speed design, such as how close they are to signals, what width they will be, where you will place the traces, and what types of components they will be connected to. Furthermore, when the factors are considered, it will achieve a high level for your PCB design process.Figure1:What is High-speed PCB Design? Ⅲ High-speed PCB Related Video High-Speed PCB Design Tips - Phil's Lab #25 High-speed PCB Video Description: Quick overview of some general high-speed PCB design tips. Everything from stack-ups, controlled impedance traces, vias, and much more! Ⅳ When Is a Printed Circuit Board Design Considered High Speed?Certain characteristics can help you identify a high-speed  PCB design,  As a result, the design is fast if:It uses  HDMI , Ethernet,  SATA , PCI Express, USB, Thunderbolt, or other high-speed interfaces for fast data transfer; the circuit consists of several sub-circuits connected via high-speed interfaces (LVDS, DSI, CSI, SDIO,  DDR3 , etc.); the time of signal propagation over the track is at least 13 of the time of signal rise; the digital signal frequency is 50MHz or higher;Because the printed circuit board is so small, locating the components becomes a real challenge (especially when you come across a high-speed interface layout  ). Ⅴ High-speed PCB Design SkillsBe familiar with design software that provides advanced options.High-speed designs necessitate a plethora of complex features in your CAD software. Furthermore, there may not be many programs for hobbyists, and it rarely has advanced options based on Web suites. As a result, you must gain a better understanding of a powerful.High-speed routing  When it comes to high-speed traces.  a designer needs to understand the essential routing rules, such as not cutting ground planes and keeping trails short. As a result, keep digital lines a certain distance apart from crosstalk and shield any interference-creating elements from compromising signal integrity.Routing traces  with impedance controlImpedance matching is required for some types of signals with impedances ranging from 40 to 120 ohms. Antennae and a large number of differential pairs are examples of characteristic impedance matched hints.It is critical for designers to understand how to calculate trace width and layer stack for required impedance values. If the impedance values are incorrect, it can have a serious impact on the signal, resulting in data corruption. When creating a PCB  layout or a high-speed PCB  layout.  keep single-ended impedance Zo and differential impedance Zdiff in mind. Figure2: Parameters for Zdiff calculation Length matching traces  High-speed memory buses and interface buses have numerous lines. Because the lines can operate at high frequencies, it is critical that the signals travel from the transmitting terminal to the receiving terminal at the same time. Furthermore, it must have a feature known as length matching. As a result, most common standards define tolerance values that must match length.Figure3: High-speed PCB Design SkillsMinimizing loop areaHigh-frequency signals can cause  EMI  and EMC issues, so high-speed PCB  designers should be aware of these tips. As a result, they must follow basic rules such as having continuous ground planes, reducing loop areas by optimizing current return paths for traces.  and incorporating numerous stitching vias. Ⅵ High speed PCB  Design ConsiderationsThe importance of the PCB  layout cannot be overstated.PCB Design ConsiderationsSchematic considerationsTrace length tuningPCB materials and stack-up demands for high speedHigh-speed placement strategiesDifferential pair and trace length routing Crosstalk, impedance control, and parallelism considerationsUnderstanding stripline and microstripRouting topologies and best routing  practicesSimulators Ⅶ Setup for High-Speed DesignBefore the layout can begin, there are several design and database details that have to be addressed.SchematicWhile there is a lot to set up before you can start the layout of a high-speed design, most people don't give the schematic much thought. Designers need to check the parts, simulate the circuitry, and finish the design. Is the schematic, however, ready to be used for layout? If the designer cannot easily understand the intent of the circuitry, an unorganized schematic can make the PCB  layout difficult. High-speed signal paths, for example, must be laid out sequentially so that the designer can replicate component placement in the layout,  It's also a good idea to highlight parts of the design that you really understand.These include:Critical placement locations, as well as which side of the board certain parts may be required onKeep out zones should be established around critical components.High-speed routing data, such as topologies, measured lengths, and matched lengths.Information about a differential pair and controlled impedance. PCB LibrariesAs with any  PCB  layout.  the component footprints used for high-speed design must be checked and verified, but some additional library work may be required. Some footprints used in high-frequency or RF designs, for example, may require modifications to reduce pad sizes for signal integrity,  In addition, to accommodate high-density design requirements, some footprints may be reduced to their smallest size. However, component footprints should always adhere to industry and manufacturer specifications to the greatest extent possible to meet design for manufacturability (DFM) requirements. Many design tools, including Cadence's Allegro  PCB Editor, include online library browsing capabilities for importing vendor-specific footprint models. Materials and ComponentsBefore you begin the layout.  you must choose the materials that will be used to construct your high-speed circuit board. Harsh operating environments may necessitate a more robust board structure, and the physical properties of the materials will be required for calculated controlled impedance routing  :Consult with your manufacturer to determine whether your board will require high-speed materials.For high-speed and high-frequency applications, enhanced epoxy or PTFE materials may be a better choice.The dielectric constants of  FR-4  may be insufficient to hold the impedance values required, or the design may suffer from greater signal loss than is acceptable.The manufacturer will also need to review and confirm the PCB components. With today's supply chain issues, you'll want to make sure you have enough parts before committing to a design. Board Layer StackupSpecific board layer stack-ups are required for high-speed designs to aid in  EMI shielding and signal integrity,  The primary concern is to include a complete and continuous ground plane on an internal layer. Many boards will also have multiple ground plane layers spread across the board stack up to accommodate multiple layers of transmission line routing in microstrip or stripline configurations. The board layer stack-up must be created in the PCB CAD database or imported from another source. This is where the ability of PCB design systems to communicate directly with the vendor for stack-up information exchange, as demonstrated in the video above, can be extremely useful. Design RulesPCB design systems typically include a comprehensive set of design rules and constraints that can be applied to the design. Component and net classes will already be used in standard circuit board designs to specify spacing rules, trace widths, vias, and other constraints. With a high-speed design, a completely new set of rules should be established, including:Differential pairsSignal pathsRouting topologiesMeasured and matched trace lengthsTrace tuning parameters These rules can be set up for each design, or in many cases, imported from another layout to ease the designer’s workload. System ParametersThe parameters are the last but not least of the setups. Display parameters such as colors and fill patterns, grids, routing preferences, and a slew of others are among them. Designers can improve their tool efficiency by managing these parameters, Let's start laying out the board now that we've completed the high-speed design.Figure5: A PCB CAD system’s parameter setup menu for design colors Ⅷ Floorplanning a High Speed PCBIn a high-speed PCB layout  , there are no specific rules or standards for where components  should be placed. In general, the largest central processor IC  should be placed near the center of the board because it will typically need to interface with all other components  on the board in some way. Smaller integrated circuits (ICs) that connect directly to the central processor can be placed around the central IC  to keep routing between components  short and direct. Peripherals can then be added to the board to provide the necessary functionality.When the main controller IC  is near the center of the board, and other high-speed peripherals are placed around it, the high-speed layout works best. This is one of the reasons why motherboards have a large processor in the center of the board. The Altium Designer MiniPC project has its PCIe, DDR4, USB 3.0, and Ethernet peripherals arranged around the central FPGA SoC to facilitate routing.Figure6: high-speed PCB layoutOnce your components  are in place, you can use your design tools to begin routing your design. This is a critical aspect of high-speed board design because incorrect routing can compromise signal integrity. However, if the preceding steps were followed correctly, signal integrity is much easier to achieve. Set your impedance profile in your PCB design rules so that all routers in the design have the proper width, clearance, and spacing to maintain controlled impedance during routing. Ⅸ How to Tell If Your Project is High SpeedThere are a couple of schools of thought on this. The unfortunate reality is that there is no specific definition of what constitutes a high-speed PCB. It all comes down to a case-by-case assessment. As previously stated, if you're experiencing signal integrity issues on your PCB layout.  it's a good indication that you're working on a high-speed project.There's also the device-specific approach to consider. You'll be working on a high-speed project if you're designing a motherboard, cell phone board, or DSL router board. If you need to incorporate specific technologies into your layouts, such as HDMI, PCI Express, USB, or SATA, be aware that you will be dealing with high-speed design constraints.Figure7: Do you believe your design has a lot of traces? Take a look at this high-speed layout The final point to consider is whether you're working on a design with lumped or distributed circuits. What's the distinction? Designs with physical systems that are all small enough that they interact uniformly are referred to as lumped systems and are not fast. However, if your systems all operate independently within the confines of a larger whole, you have a distributed system and some high-speed design issues to deal with.Here is what you should remember:When the trace length becomes a significant fraction of the wavelength of the fastest signal, high-speed design considerations need to be considered.ⅩFAQ1. What is considered high speed design?High speed design specifically refers to systems that use high speed digital signals to pass data between components. The dividing line between a high speed digital design and a simple circuit board with slower digital protocols is blurry.2. What is high speed design Altium?High-Speed Design in Altium Designer. High-speed printed circuit board design is a process of balancing the circuit design requirements, device technologies, and fabrication materials and methodologies, to deliver a PCB that can transfer signals between the components, with integrity.3. What are high speed interfaces?High-Speed Serial Interface (HSSI) is a short-distance (50') communications interface that is used to interconnect routing and switching devices on slower local-area networks (LANs) with the higher-speed lines of a wide area network (WAN).4. What is high frequency PCB?High Frequency PCB is a type of PCB which is widely used in applications involving special signal transmission between objects. It is available in frequency range of 500MHz to 2GHz and is an ideal choice for mobile, microwave, radio frequency and high speed design applications.5. What is high speed signal in PCB?What is a high-speed signal in a PCB? Signals with frequencies ranging from 50 MHz to as high as 3 GHz are considered high-speed signals such as clock signals. Ideally, a clock signal is a square wave, but it is practically impossible to change its 'LOW' level to 'HIGH' level (and vice versa) instantly.

Introduction Do you use Raspberry Pi? or What are doing with it? Is it a microcontroller (MCU for microcontroller unit) or microcomputer? or SoC (system-on-chip)? As a beginner, is it better to buy a microcontroller or a Raspberry Pi? Look at the following content. Raspberry Pi Explained Catalog Introduction Ⅰ Basic Definition Ⅱ Raspberry Pi vs MCU Ⅲ What Can We Do with Raspberry Pi? Ⅳ Where do I start to Learn Raspberry Pi? Ⅴ FAQ Ⅰ Basic Definition Raspberry Pi is actually a tiny embedded computer. It uses ARM microcontroller chip, and linux operating system or windows. It can regard as a small desktop computer when connects with a monitor, keyboard, and network (network port or wifi). With the release of Windows 10 IoT, Raspberry Pi can also run Windows.The single-chip microcomputer refers to the central processing unit core with some peripheral interface circuits on it, which is also called the microcontroller unit (MCU), or SoC. 8051 chips, avr chips, arm chips, etc. are all called single-chip microcontrollers, while Intel’s 80x86 series are central processing unit (CPU) and cannot be called MCU.It uses very large-scale integrated circuit technology to integrate the central processing unit CPU with data processing capabilities, RAM, ROM, multiple I/O ports and interrupt systems, timers/counters and other functions (may also include display driving circuits, pulse width modulation circuits, analog multiplexers, A/D converters and other circuits) are integrated on a silicon chip to form a small and complete microcomputer system. It is widely used in the field of industrial control. Figure 1. Raspberry Pi Setting Ⅱ Raspberry Pi vs MCU Next, let's take a look at the difference between the Raspberry Pi and the MCU and introduce in detail what can we do with the Raspberry Pi?The single-chip microcomputer is an microcontroller, and the Raspberry Pi is a single-board computer with arm-architecture processor. Early MCUs were peripherals for ROM and IO with slow speed, and it could not run time-sharing operating systems such as Linux or Windows. But the Raspberry Pi can run an operating system like Linux, or deploy servers or cloud computing. That is, the Raspberry Pi can perform many operations that cannot be done by a single-chip microcomputer.The size of the single-chip microcomputer is relatively small, and the internal chip is used as a computer system. Its structure is simple, but the function is perfect, it is very convenient to use, and it can be modularized. The most important thing is that although the development cycle of the single-chip microcomputer is relatively short, it is basically based on a specific task and the code must be re-programmed every time, which is very troublesome.The Raspberry Pi is actually a computer motherboard. It can be programmed, compiled, and run directly locally. If you want to add or delete functions to the original program, or switch from the current task to a different new task, you do not need to burn programs like a single-chip microcomputer according to different tasks or updates. Use Raspberry Pi to control peripherals by operating GPIO basically through various libraries, and if you connect it to the Internet, you can operate it remotely. Figure 2. Raspberry Pi GPIO In general, each has its own advantages. The MCU is cheap and suitable for general consumer products. After all, the Raspberry Pi is a card-type computer with an embedded operating system running on it. That is, a low-power general-purpose computer. For electronic geeks, the back-end data processing and GUI for complex control systems are still very good for satisfying embedded learning. Ⅲ What Can We Do with Raspberry Pi? After reading the above, since Raspberry Pi has the features of a computer, this means you’re able to do most things a desktop computer can do such as document editing, playing HD video, playing games, coding and much more.Obviously it won’t have as much power as a desktop PC but since it is a lot cheaper they make for great little computers you can play around with.Here lists some items you can do:1) Wireless HotspotUsing the Internet cable and USB wireless network card, after configuration, it can be used as a wireless hotspot.2) Mechanical ProsthesesMIT Media Lab researchers use it as a controller for mechanical prostheses.3) Easy Homemade NotebookConnect the Raspberry Pi to the LCD panel, add the mouse, keyboard and power supply, and find a beautiful case and put it on, finally it becomes a simple homemade notebook.4) WiFi CarAn IBM engineer installed it on a model car, and then used WiFi signals to control the car’s actions.5) Send Dynamics RemotelyWeather enthusiasts tied it to a detection balloon and used it to send a tweet in the stratosphere.6) Control Door SwitchThere are also people who use the Raspberry Pi to control the garage door and combine it with Siri to remotely control the garage switch.7) Surveillance ShootingA camera is connected as a small shooting device, which is small in size and easy to hide.8) Back Up EmailsOne of the most important functions of my Raspberry Pi is to back up emails. Use a software called getmail to check every mail using POP or IMAP protocol, and check the mail of each account regularly. Then save the email to an mbox file, which can be copied to another computer at any time for long-term email archiving.9) Build a RSS ReaderMiniflux, a self-hosted web-based RSS client that can be installed on the Raspberry Pi. Like many people, when Google announced that it would close Google Reader on July 1st, I also started to migrate personal data. I used rss2email for a while and let it send every item of RSS to my mailbox. But in fact, I don't like this method very much, so I spent some time looking for alternatives to Google Reader and tried rss2email and found miniflux finally. Installing miniflux on the Raspberry Pi is very simple, you only need to install PHP and a web server software in advance, such as nginx or Apache.10) Build a WebsiteOne obvious use of Raspberry Pi is as a backend server for websites. Because it has enough capacity to handle static websites, some web frameworks are not a problem. I built a Flask framework on it, and I even heard that some people built a Wordpress directly on the Raspberry Pi.11) Home Network StorageOnly consumes very low power, Raspberry Pi can become a perfect NAS (Network Attached Storage). Before I connected a 500GB laptop hard drive to the Raspberry Pi and installed an operating system on it. I can store many files on it that need to be transferred between different computers. Then connect via SFTP, you can access it on any machine at home (even if you are not at home, it will not be a problem as long as the routing settings are correct). You can also install Samba on your Pi so that both Mac and PC can access it more easily.12) Site MonitoringUse Raspberry Pi is to detect websites that are important to me. I wrote a Python script and ran it regularly to make sure that these websites responded with a 200 status code (which means everything is normal). If the script determines that there is a problem with the website or cannot be accessed, it will email me the overall situation of the incident. The Python module I use is Requests, and the email module is smtplib.13) Event ReminderUse Raspberry Pi to email me important events that I need to remember. I used Google Calendar before, but I only use it for simple events. So I replaced it with a Raspberry Pi, and a Python script for timed tasks is enough. I set the date, time, and message to remember. These parameters will be passed to my Python script, and on that day it will send the message to my mailbox to remind me of the day’s events.14) Family AlbumMy Raspberry Pi also supports a private website that contains all my family photos. I set up verification information so only people I want them to see can enter the site. This is much more reliable than your Facebook photo album, because your account on Facebook may be deleted, and the photos will be seen by strangers by chance. Here is a method, just use PHP to get the photos in a folder on the Raspberry Pi.15) JukeboxI mentioned above that I use Pi as a network storage, so all my music is also on it. I connected a stereo speaker to my Pi and used mpg123 to play music on the command line of the Raspberry Pi. Although there are many other mp3 players and graphical interfaces, I still choose mpg123 because it is easy to install and use. Figure 3. Raspberry Pi Projects Ⅳ Where do I start to Learn Raspberry Pi? If you are really interested in it and want to get started. How, and what do you need? 1) A Raspberry Pi. So, obviously you’ll need he actual board. If you don’t have it, you cant really do what you want. So find a website or store and buy one. Depending on the type and model you get, they can range from as low as 10$ to 50$. Pretty affordable.2) A monitor. So, you don’t actually need a monitor. But it is going to be so much easier. You can actually buy displays the Pi company has made specifically made for the Pi. These however are a little more expensive.You could also use your TV as a monitor, providing both the TV and the Pi can be hooked up via HDMI. VGA to HDMI would work too. Many different solutions can be used when it comes to the cable you use for a monitor, or all around screen. Adapters come in all shapes, sizes and forms. 3) A power source. You’ll need to power the Pi to use it. Most of the time, you will get a little charger to use with the Pi. Using this specific charger will probably be the best, as it will always pull enough power from the wall into your Pi.4) A mouse, and keyboard. You will need a mouse and keyboard. This is pretty much mandatory. Well, only for the actual screen portion of the Pi. Models 3 B+ and up have built in Bluetooth, so you can have cordless mouse and keyboard if you would like. That’s pretty cool.5) Depending on the model, you will need an Ethernet cable to have internet. Models 3 B+ and up have a built in WiFi chip. So you can have a wireless internet connection if you so please.6) A microSD card with the image you want to use. When you buy the Pi, you will need to have an SD card. The newer models use microSD cards. Putting the SD card into the Pi without anything on it wont do anything though, you'll need an image. Images for the Pi can be found along the internet for downloads. The standard image used for the Pi right now is NOOBS Debian.7) Time, patience and dedication. These are very important when working with the Pi. Why? Because the Pi is powerful, yet it can be confusing at times, especially for a “noob”.   Ⅴ FAQ 1. What is Raspberry Pi mainly used for?The Raspberry Pi is a low cost, credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing, and to learn how to program in languages like Scratch and Python. 2. What are some good Raspberry Pi projects?Best Raspberry Pi Projects for BeginnersMusic Streaming.Security System.Weather Station.Arcade Machine.NAS.Digital Photo Frame.Retro Handheld Console.Robot. 3. Can a Raspberry Pi run Windows?The Raspberry Pi 4 can handle Microsoft Edge, the calculator app, and more, all via the power of Windows 11. It can even run Minecraft, albeit in an undesirable state. 4. Can Raspberry Pi go on Internet?If you want to connect your Raspberry Pi to the internet, you can plug an Ethernet cable into it (if you have a Raspberry Pi Zero, you'll need a USB-to-Ethernet adapter as well). If your model is a Raspberry Pi 4, Raspberry Pi 3, or Raspberry Pi Zero W, you can also connect to a wireless network. 5. How do I setup a Raspberry Pi network?Configuring the Raspberry Pi Ethernet Port With a Static IP.Step 1: Review Current Network Settings.Step 2: Backup the Current Network Configuration.Step 3: Modify the Network Settings. To edit the network setting you must edit the dhcpcd.Step 4: Restart the Raspberry Pi.Step 5: Test the New Network Setup. 6. How is Raspberry Pi different from microcontroller?The main difference between them is: Arduino is microcontroller board, while Raspberry Pi is a microprocessor based mini computer (SBC). The Microcontroller on the Arduino board contains the CPU, RAM and ROM. 7. Is Raspberry Pi zero a microcontroller?A Raspberry Pi is not a microcontroller, it is a single board computer. Neither. The chip itself is an SOC or system on chip, so it has almost all the parts of a computer on a single die. 8. Is the Raspberry Pi a system on a chip?Raspberry Pi SBCs feature a Broadcom system on a chip (SoC) with an integrated ARM-compatible central processing unit (CPU) and on-chip graphics processing unit (GPU), while Raspberry Pi Pico has a RP2040 system on chip with an integrated ARM-compatible central processing unit (CPU). 9. Can you use a microcontroller with a Raspberry Pi?Meet the Raspberry Pi Pico, a tiny little microcontroller that lets you build hardware projects with some code running on the microcontroller. Unlike computers, microcontrollers don't run traditional operating systems. 10. Is Raspberry Pi 3b a microcontroller?The Raspberry Pi is a single board computer with Microprocessor whereas Arduino is considered as Microcontroller unit. The Raspberry Pi can run an OS (Linux Distribution) and also consumes more power. Since Arduino is microcontroller device it has no operating system and can only run a single program or sketch. 11. What is Raspberry Pi used for in IoT?How can IoT Applications use Raspberry Pi? With an in-built quadcore processor, Raspberry Pi can serve as the “Internet Gateway” for IoT devices. Powered by a cloud network, Pi acts as a web server for uploading and transiting sensor data on IoT platforms. 12. What is the difference between microprocessor and microcontroller?KEY DIFFERENCESMicroprocessor consists of only a Central Processing Unit, whereas Micro Controller contains a CPU, Memory, I/O all integrated into one chip. ... Microprocessor uses an external bus to interface to RAM, ROM, and other peripherals, on the other hand, Microcontroller uses an internal controlling bus. 13. What kind of computer is Raspberry Pi?The Raspberry Pi is a low cost, credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing, and to learn how to program in languages like Scratch and Python. 14. Can I use a Raspberry Pi as my main computer?Aside from the hard drive crash, the Raspberry Pi was a perfectly serviceable desktop for web browsing, writing articles, and even some light image editing. ... 4 GB of ram is just enough for a desktop. My 13 Chromium tabs, including a Youtube video, are using just over half of the 4 GB of available memory. 15. Which OS is better for Raspberry Pi?Raspbian. Raspbian is a Debian-based engineered especially for the Raspberry Pi and it is the perfect general-purpose OS for Raspberry users.