How To Control The Reverse Direction Of The Servo? 6 Ways To Get It Done From Hardware To Software

Want to make theservoreverse but find it doesn't move at all? Don’t worry, this problem is actually very common. The rotation direction of theservois mainly determined by the control signal. Whether you are making a robotic arm, a smart car or a model aircraft, mastering the reversal method can make your design more flexible. The following 6 methods are available from hardware to software, there is always one suitable for you.

How to control the reverse direction of theservoby modifying the PWM signal

The PWM signal is the pulse width modulation signal through which the servo is positioned. Generally, a pulse of 1.5 milliseconds corresponds to the middle position, 1 millisecond corresponds to 0 degrees, and 2 milliseconds corresponds to 180 degrees. To achieve inversion, you need to reverse the original pulse range. For example, 0 degrees corresponds to 1 millisecond, and 180 degrees corresponds to 2 milliseconds. Now let 0 degrees correspond to 2 milliseconds.

In actual operation, you only need to map the output angle in the program. Suppose you originally used the map function to map 0-180 to 1000-2000 microseconds, and now directly change it to map to 2000-1000 microseconds. In this way, when the maximum pulse is sent, the servo rotates to the minimum angle, which seems to be reversed.

How to make the servo reverse direction by modifying the wiring

This method is only applicable to ordinary DC servos, not standard aircraft model servos with control circuits. If you are using a continuous rotating servo with only two wires, red and black, you can change the direction of rotation by simply swapping the positive and negative poles. But please note that standard servos with three wires (signal wire, power wire, ground wire) cannot do this.

Because there is a control chip inside the standard servo, it will determine the direction of rotation based on the PWM signal. Changing the wiring will not only not reverse the direction, but may also burn out the circuit board. Unless you disassemble the servo, swap the two wires of the motor, and then swap the wires at both ends of the potentiometer, this operation is risky, and it is not recommended for people with disabilities to try it.

How to use programming to control the reverse direction of the servo

Using the control servo to reverse is one of the simplest methods. First include the Servo library and then define a Servo object. In the loop, you only need to use the write function to send the angle value. For example, if you want it to move in the reverse direction, send 180 minus the current target angle.

# Servo ; int = 90; void setup() { .(9); } void loop() { int = 180 - ; .write(); delay(15); }

In this way, the position that was originally going to be rotated to 90 degrees will actually be rotated to the symmetrical position corresponding to 90 degrees, achieving direction reversal. If you are using a continuous rotation servo, just send 0 or 180 to control forward and reverse rotation.

How to determine whether the servo supports software reversal direction

Not all servos support direct setting of the reverse direction through software. After the analog servo receives the PWM signal, the internal circuit directly drives the motor. If you want to change the direction, you have to change the signal mapping. There is a microprocessor inside the digital servo, and some models support forward and reverse mode configuration through programming.

You can check the servo model manual to see if there are "" or "" related setting parameters. For example, some serial bus servos (like AX-12A) can modify the direction of rotation by sending specific instructions. If you can't find the information, the easiest way is to test by sending signals and observe the response.

How to avoid damaging the motor when the steering gear is reversed

The most common problems when the servo is reversed are mechanical limits and excessive current. Many servos have internal mechanical limits. Forcing it to a position beyond the range will cause the gear to get stuck or even burn out the motor. Therefore, before performing reverse rotation control, you must first confirm whether your servo is a 360-degree continuous rotation or a limited 180-degree servo.

If it is a limited-limit servo, you need to limit the angle range in the program, such as only allowing it to move between 0-180 degrees. In addition, sudden load changes during reversal may cause the current to surge. It is recommended to connect a large capacitor (such as 470uF) in parallel to the power supply end to stabilize the voltage and prevent the microcontroller from resetting.

How to manually control the reverse direction of the servo through a potentiometer

Want to do a quick test or don't want to write code? Manual control with a potentiometer is a good idea. Connect a 10K potentiometer to the analog input pin, read the voltage value and map it to 0-180 degrees, and then output it to the servo. To achieve reversal, you just need to reverse the mapping relationship.

The wiring is very simple: the middle pin of the potentiometer is connected to A0, and both sides are connected to 5V and GND. In the code, the value is read, then map is used to map it into an angle, and finally .write is used to output it. Turn the potentiometer knob and you can see the servo follow in the reverse direction, which is especially suitable for prototype verification or teaching demonstrations.

What other troublesome control problems have you encountered when working on steering gear projects? Welcome to share your experience in the comment area and give it a like so that more makers can see these practical methods.