TECHNICAL SUPPORT
Published 2026-02-27
The biggest headache when playing withservos is the wiring, especially the power supply part. Many friends have finally written the program, but the result is that theservoeither doesn't move or vibrates randomly. Nine times out of ten, the power supply is not connected correctly. Today we will talk about what to do with the power supply when theservois connected to a microcontroller.
When you get a servo, the first thing you need to figure out is which wire has what purpose. On the market, most servos are equipped with three wires, and their colors are basically fixed: brown or black represents the negative electrode (GND), red represents the positive electrode (VCC), and orange or yellow represents the signal line. The meanings represented by these three lines are like the identity card of the steering gear, which can be clearly identified at a glance.
This correspondence between color and function is very important for people who are new to servos. It provides clear guidance for the subsequent correct connection of the servo to the circuit, preventing the servo from malfunctioning due to connection errors. As long as you remember the corresponding functions of these three wires, you can more smoothly carry out operations related to the steering gear. Whether it is a simple test or a complex project application, you can lay a good foundation.
However, in actual situations, there are some servos that do not follow the conventional line setting method. For example, some aircraft model servos use white or blue wires to transmit signals. In order to ensure safety and correct operation, it is best to carefully check the label on the servo or the instruction manual that comes with the product. If you really can't find the relevant instructions, using a multimeter to measure is also a feasible method. Usually, a voltage of about 5V can be measured between the red wire and the black wire.
People often get this question wrong. The working voltage of the servo is not determined arbitrarily, it depends on the model. Common servos have two specifications: 4.8V and 6.0V. There are also some high-voltage servos that can support 7.4V or even higher. If the voltage is too high, the servo will get hot and burn out; if the voltage is too low, it will have no power and cannot turn.
For example, if you buy a servo and its marked power supply range is 4.8V to 6.6V, then it is feasible to use 5V or 6V voltage. However, if you are using the 5V power supply method on the board, you need to consider it carefully. Because the current provided by the ordinary small onboard voltage regulator chip is insufficient, it is very difficult to drive a servo. Therefore, it is best to power the servo separately, or use an ESC with BEC.
The current when the servo is started can startle people. When a standard servo is blocked, it can consume 1A or more current. If it is directly powered by a microcontroller, the board will be burned in minutes. This is not an alarmist statement. I burned a few pieces when I first started playing.
Solving this problem is actually not difficult, and the simplest way is to connect an external power supply. You can choose a 18650 battery or 4 AA batteries to power the servo independently, and then let it share the ground with the microcontroller. What needs to be especially remembered is that the land must be shared! The specific method is to connect the negative pole of the servo power supply and the negative pole of the microcontroller power supply together. Only in this way can the signal be transmitted normally.
The key to the normal operation of the servo is a stable power supply and correct grounding method. When powering the servo through an external power supply, operate it strictly in accordance with the requirements. For example, choose the appropriate battery type, such as 18650 batteries or 4 AA batteries, to ensure that it can provide stable power to the servo. During the connection process, connect the negative pole of the servo power supply to the negative pole of the microcontroller power supply to form a common ground connection. This step plays a decisive role in the normal transmission of signals. Once the common ground connection is incorrect, signal transmission will be affected, causing the servo to not work properly.
This question depends on the score. If you are using the USB power supply on the development board, it is basically useless. The maximum 5V of USB is 500mA, which cannot drive the servo. If you use a 12V power supply to power the microcontroller, it depends on the output capability of the board after voltage stabilization, which is generally not enough.
The safe approach is to separate the power supplies. The microcontroller uses computer USB or low-power power supply, and the servo uses battery or high-power power supply. Only signal lines and common ground lines are connected between them. This is just like your refrigerator and TV are not plugged into the same socket. Although they are both electrical appliances, the voltage drop when the refrigerator is started is too large, and the TV screen will flicker.
When the steering gear is working, the current fluctuation is particularly large, which will produce burrs on the power line and affect the operation of the microcontroller. To solve this problem, a large capacitor needs to be connected at both ends of the servo power supply. As for the capacity, it can range from 470 microfarads to 1000 microfarads, and the withstand voltage should be higher than the supply voltage.
The function of the capacitor is like adding a buffer pool to the power supply. When the servo suddenly needs power, the capacitor will top up first to prevent the voltage from being pulled down. It is best to add a 0.1 microfarad ceramic capacitor to filter out high-frequency interference. Place the capacitor as close to the servo terminal as possible. The closer the capacitor is, the better the effect will be.
There are many servo power supply solutions available on the market, so don’t be dazzled when choosing one. One of the simplest ways is to use this type of step-down module, which can reduce the voltage of 12V or higher to 5V or 6V. However, when choosing, you should choose a model with a larger current, at least 3A or more is safer.
In addition, you can also directly use model aircraft batteries with UBEC. UBEC itself is specially designed for servos, and its power supply effect is very stable.
Another lazy way is to buy a dedicated power strip for the servo. There are many on Taobao, just search for "servo power supply board", it has several output ports, and some also has over-current protection, which makes it worry-free to use. Remember to check the input voltage range and output current clearly when choosing, calculate the number of servos you use, and leave a margin.
What strange problems have you encountered when connecting the servo? Welcome to share your pitfall experience in the comment area, like and bookmark this article, and read it directly next time you play with servos. If you want to know more about steering gear control techniques, you can search our company's official website, which has a full set of tutorials and case codes.
Update Time：2026-02-27
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