TECHNICAL SUPPORT
Published 2026-03-12
The most troublesome thing about playing withservos is that the code is written but theservos don’t obey. It either shakes non-stop, gets stuck halfway, or even doesn't respond at all. Looking at a pile of codes and the constantly shakingservois really frustrating. In fact, most of the problems are not with the servo itself, but with some details in the code implementation that were not handled well. Today I will sort out my experience in tinkering with servos over the past few years to help you bypass those pitfalls.
Many people who write servo code for the first time are accustomed to directly using the delay function to control the rotation angle. For example, first give a high level signal, then delay 1.5 milliseconds, and then give a low level signal. This method is barely usable when controlling one servo alone, but as long as it is slightly more complicated, such as controlling several servos at the same time, or trying to do something else during the rotation gap, problems will immediately arise. The delay function will block the entire program from running, just like if you suddenly hit the brakes while driving, nothing can be done. The correct approach is to use a timer to generate PWM waves, let the servo signal continue to be output in the background, and the main program should do whatever it wants.
The Servo library is really simple and easy to use. A few lines of code can make the servo move. But if you are doing product development, this library has many limitations. It can only support up to 12 servos, and it takes up timer resources, making it troublesome to use other functions at the same time. If you are working on a slightly more complex project, it is recommended to use this type of servo driver board library. 16 channels are independently controlled, with higher resolution and without occupying the timer of the main control chip. Many servo control boards now support cascading, making it easy to control dozens of servos in one product.
There are usually two situations when the servo shakes. One is that the power supply is insufficient. The current when the servo is started is very large, and the USB power supply cannot handle it at all. The solution is very simple. Use an external power supply to power the servo separately. The ground wires of the main control board and the servo must be connected together. The other is that the control signal is unstable, especially when the signal line is too long. You can add a 100-200 ohm resistor to the signal line, or add a large capacitor at both ends of the servo power supply, which can significantly improve the jitter. Another trick is to add a smooth start in the program. When powering on, give it a smaller angle first, and then wait for the servo to stabilize before turning to the target position.
Some application scenarios require simultaneous movement of multiple servos, such as the arm joints of a robot. At this time, sequence control cannot be used. After one turns, the other turns. The correct approach is to first calculate the target angles of all servos, and then send commands at the same time. It is a good idea to use a scheduled interrupt, which is triggered every 20 milliseconds and updates the PWM duty cycle of all servos in the interrupt service routine. If you use a servo driver board, it will be even simpler. You can directly package and send all the angle data, and the driver board will handle the synchronization problem by itself. Remember to plan the motion at the algorithm level to make the coordinated action of multiple servos smoother.
Digital servos have high theoretical accuracy, but in actual use there will always be some deviations. On the one hand, it is the error of mechanical installation, and on the other hand, it is the dead zone range of the steering gear itself. To solve this problem, you can perform angle calibration in the code. First, let the servo rotate to the minimum angle and maximum angle, record the actual position, and then establish a mapping relationship. For example, if you want to rotate 90 degrees, the actual control signal given may be a value of 92 degrees. Another detail is that the middle position of the servo is often the most accurate, so try to keep the commonly used working range in the middle area. If the requirements are particularly high, you can consider adding a potentiometer for closed-loop control and real-time feedback of angle information.
Making a prototype and making a product are completely different things. When writing product code, exception handling needs to be fully considered. For example, if the steering gear gets stuck, how to take effective protection measures; how to implement recovery operation after communication is interrupted. At the same time, a watchdog should be added to the code to regularly check the status of the servo. In addition, the issue of power consumption cannot be ignored, especially for products that rely on battery power. When the servo is not working, it can be put into low-power mode, or the PWM signal can be turned off directly. In the mass production stage, there are subtle differences in the mechanical installation of each device, so a calibration interface can be reserved in the code and an automatic calibration program can be run before leaving the factory. Moreover, it is best to encapsulate the code related to the servo control into an independent module, so that when the servo model is changed in the future, it will be more convenient to modify.
When making products, in addition to the above mentioned, you also need to pay attention to more details. Make sure exception handling in production code is comprehensive and effective. For example, when the servo gets stuck, a complete protection mechanism must be developed to avoid product damage due to abnormalities. The recovery strategy after communication interruption also needs to be carefully designed to ensure that the product can quickly resume normal operation. Add a watchdog to check the status of the servo, so that potential problems can be discovered in time and measures can be taken. In terms of power consumption, optimizing low-power mode settings for battery-powered products can extend product life. Taking into account the differences in the mechanical installation of equipment during mass production, reserving calibration interfaces and executing automatic calibration procedures can improve product consistency and stability. Encapsulating the steering gear control code into an independent module provides great convenience for future product upgrades and maintenance, and can more efficiently respond to steering gear model changes and other situations.
After reading the implementation points of these steering gear codes, have you also discovered possible problems in your own project? Think about it, what is the strangest phenomenon you have ever encountered when debugging the servo? Welcome to share your experience in the comment area, maybe it can help other friends avoid the same pitfalls. If you find the content useful, remember to give it a like and support it so that more friends who are involved in servo control can see it.
Update Time：2026-03-12
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