TECHNICAL SUPPORT
Published 2026-03-25
Have you ever encountered this situation: you bought aservoand wanted to use it on your little invention, but when you plug it in, it either doesn’t move or vibrates crazily? Don't worry, it's not that theservois broken, it's most likely that you haven't found the correct way to "communicate" with it. Today we will talk about how to write a program for theservoso that it can obey your instructions and turn it as much as you want.
Many friends just casually connected the three wires of the servo (power, ground, and signal) to the development board as soon as they started, and then started to doubt their life when they saw the servo "twitching". In fact, the root cause of servo vibration is, most of the time, insufficient power supply. There is a small motor inside the servo, and the instantaneous current when starting is very large. If your power supply (such as the 5V pin on the board) cannot provide this instantaneous current, the voltage will be pulled down, causing the chip logic inside the servo to be confused.
Another common reason is that the signal cable is not connected correctly, or the PWM signal frequency sent by the program is incorrect. The servo controls the angle by sending a specific pulse width of 50 times per second (that is, 50Hz) on the signal line. If you set other frequencies in the program, the servo will not understand what you are saying and will naturally start to move randomly. Check your code to see if the PWM frequency is not set to 50Hz.
This problem is directly related to whether the steering gear can work normally. If you only use one servo, and it is a small servo like 9g, you can barely use the 5V pin of the development board to supply power directly, but it is really only "barely". For system stability, it is strongly recommended to provide separate power supply to the servo. You need a 5V power supply that can provide at least 1A of current, such as three dry batteries in series, or a mobile phone power bank plus a boost module.
Never connect the power cord of the servo and the power cord of the development board reversely, otherwise things will burn. The correct connection method is: the red wire (VCC) of the servo is connected to the positive pole of your independent power supply, and the black wire (GND) is connected to the negative pole of the power supply. This black wire must be connected to the GND of the development board. This is called "common ground" and is the key to signal stability. Many novices will ignore this step, causing the signal line to "float" and the servo to be disobedient.
If you want to play with the servo, you need these things on hand. In terms of hardware: a servo (the most common is SG90 or so), a microcontroller development board (Uno is the easiest to use), a few DuPont wires, and a battery box or power module that can power the servo. If it is your first time to play, Uno is the easiest to use because its built-in programming library supports servos very well.
Software-wise, you need to download an IDE, which is free. After installation, select your development board model and serial port number in the "Tools" menu. Here is a little trick. There is a "Servo" example in the IDE's sample program. Open it directly and you will see the simplest servo control code. You only need to change the pin number of the servo signal line and upload it to the board. The servo should start to swing back and forth. This is your first step in programming.
Let’s go a little deeper and talk about the key PWM signal. The full name of PWM is pulse width modulation. To put it bluntly, there is a high-level pulse on the signal line every 20 milliseconds (because the frequency is 50Hz). The length of time this pulse lasts determines the angle to which the servo will turn.
Usually, when the pulse width is 0.5 milliseconds, the servo rotates to 0 degrees; when 1.5 milliseconds, it rotates to 90 degrees; when it is 2.5 milliseconds, it rotates to 180 degrees. When you use the.write(angle)function, it will automatically convert the angle into the corresponding pulse width for you, and you don't have to worry about the underlying details at all. If you are using another microcontroller, such as STM32, you may need to use a timer to generate this precise PWM waveform yourself. It is a little more complicated, but the principle is exactly the same.
Come on, let's write a program that can make the servo rotate back and forth. The first step is to open the IDE and create a new project. In the second step, use# at the beginning of the code to introduce the servo library. The third step is to create a servo object, such asServo ;Step 4: Insetup()function, use.(9);to declare that the servo signal line is connected to pin 9.
The fifth step, which is also the core part, is to write your control logic inloop()function. For example, if you want the servo to turn to 0 degrees first, wait for 1 second, then turn to 180 degrees, wait for 1 second. Then the code is:.write(0); delay(1000); .write(180); delay(1000);. It's that simple. After uploading the code, you will see the servo swing back and forth between the two angles you set. At the moment you succeeded, did you feel a special sense of accomplishment?
Based on my own experience, there are several mistakes that are a "stumbling block" for newbies. The first is to forget about “common ground”. The GND of the development board and the GND of the servo power supply must be connected with wires, otherwise the control signal is like data without a reference system and is completely unreliable. The second is to connect the signal line to a pin that is not supported by PWM. Only pins 3, 5, 6, 9, 10, and 11 on Uno support PWM output. If you connect to pin 2 or 4, the program will compile and pass, but the servo will not move.
The third mistake is to think that the servo angle must be continuously adjustable. In fact, the physical limit of many servos is 0 to 180 degrees. If you writewrite(200)in the program, the servos will either be stuck at 180 degrees, or they will make a "click" sound and try to cross the limit. Over time, they will easily burn out. In addition, when the battery power that powers the servo is insufficient, it may become weak, shake, or stop halfway. So when you encounter a problem, check the wiring first, then the power supply, and finally suspect the code. This sequence can save you a lot of time.
Have you ever encountered any "supernatural events" when debugging the servo? For example, does it suddenly start drawing circles on its own, or is it particularly sensitive to temperature? Welcome to share your experience in the comment area, and let’s discuss it together. If you want to get more detailed servo selection and code examples, you can search the "Toshiba Semiconductor" official website. There are a large number of application notes and reference designs there, which will definitely be a good helper on your development journey.
Update Time：2026-03-25
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