TECHNICAL SUPPORT
Published 2026-02-10
When many friends come into contact with theservofor the first time, they will feel a little confused when faced with the rows of leads of different colors and unfamiliar interface definitions. Don't worry, this is a very common problem. If the line sequence and definitions are unclear, theservomay not work at best, or the controller may be burned out, causing valuable innovative projects to be stuck in the first step. Today we will thoroughly clarify theservointerface, so that you can confidently turn your ideas into a moving reality.
A servo usually has three wires, which is the basic logic behind its operation. You can think of it as a small execution unit that needs to receive instructions, get energy, and keep the circuit open. These three wires each perform their own duties and are indispensable. Together they determine the position, speed and strength of the steering gear.
Specifically, these three wires correspond to the signal, the positive pole of the power supply, and the negative pole of the power supply (ground wire). The signal line is responsible for receiving pulse commands from the controller (such as a microcontroller and a servo control board); the positive and negative poles of the power supply provide the power required for the operation of the motor and circuit inside the servo. If any wire is connected incorrectly, the entire system will not function properly.
The most common servo wire color combinations are brown, red, and orange. In this conventional standard, the brown wire corresponds to the negative pole of the power supply (GND), the red wire corresponds to the positive pole of the power supply (VCC, usually +5V), and the orange (or yellow) wire is the signal wire (). Remembering this formula of "brown, negative, red, positive and orange signals" can solve most problems.
However, not all servos follow this color scheme. You may come across a combination of white, red, and black, or a combination of blue, red, and yellow. Don't take it for granted at this time. The most reliable way is to consult the product manual of the steering gear. If you don't have one at hand, a safe approach is: usually the middle wire is the positive power supply (VCC). This is the default layout of many manufacturers, but it is best to confirm it by measuring it with a multimeter.
The core control method of the steering gear is called pulse width modulation (PWM). Don’t be scared by this word, it’s actually very simple: the controller sends a series of repeated pulses through the signal line, and the internal circuit of the servo will measure the duration of each pulse (i.e., pulse width), and determine which angle the output shaft should turn based on this width.
For example, a pulse width of 1.5 milliseconds usually corresponds to the center position of the servo (0 degrees or 90 degrees), a pulse width of 1 millisecond may correspond to the left limit (-90 degrees or 0 degrees), and a pulse width of 2 milliseconds corresponds to the right limit (+90 degrees or 180 degrees). The pulse signal keeps repeating, and the servo will continue to adjust its position to match the latest instructions. This is the underlying principle that allows the robotic arm to accurately grasp objects by changing a value through code.
The first step in connecting the servo is to confirm that the voltages match. Make sure the power output of your control board (such as Raspberry Pi) is consistent with the working voltage of the servo (commonly 4.8V-6.8V). If the steering gear requires a large current, be sure to use an independent power supply to avoid damage to the control board due to overload.
During actual operation, first align the servo interface with the pin header or socket on the controller. Generally, the signal line should be aligned with the pin marked "S", "Sig" or "PWM", the positive pole of the power supply should be aligned with "VCC" or "+", and the negative pole should be aligned with "GND" or "-". If you use DuPont wire for connection, it is recommended to check the wire sequence again before turning on the power. The moment the connection is reversed, damage may occur.
The most common cause of interface burnout is that the power supply is connected incorrectly or the voltage is too high. If the positive and negative poles of the servo are connected reversely, the internal circuit will instantly withstand reverse voltage, which can easily cause the chip or motor to burn out. Similarly, using a voltage much higher than the rated voltage (such as connecting a 12V power supply to a 5V servo) will also have catastrophic consequences.
Another invisible killer is stalled current. When the steering gear reaches the extreme position and is stuck by the mechanical structure, but the control signal still commands it to continue rotating, the motor coil will rapidly heat up due to the continuous high current and eventually burn out. Therefore, hard limits should be avoided in mechanical design, and reasonable rotation range protection should be set in the software.
When choosing a servo, you must first clarify the torque, speed, size and accuracy requirements of your project. For robot joints, high-torque metal gear servos may be required; for model aircraft, fast and light-weight models are preferred. Checking these key parameters in the product specification is more important than simply looking at the brand.
When choosing accessories, don’t ignore the quality of connecting cables and connectors. The internal resistance of inferior wire is large, which will cause the voltage to drop and the servo to be unable to vibrate. It is recommended to choose accessories with sufficient wire diameter (such as 22AWG), less oxidation of gold-plated connectors, and tight plugging and unplugging feel. A reliable power adapter is as valuable as the servo itself. It can provide clean and stable current, which is the basis for the long-term stable operation of the entire system.
I hope these clarifications can help you clear up the obstacles in servo connection. In your recent projects, have you ever delayed progress due to a seemingly simple interface problem? Welcome to share your experiences and insights in the comment area. If you find it helpful, don’t forget to like and share it with more partners who may need it.
Update Time：2026-02-10
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