# DC servo motor shake/vibrate too much

I have a servo motor (details are here). I wrote a code in Arduino to rotate it in some defined angles and position. Code is given below:

void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
Serial1.begin(9600);
Serial1.println("M40");
}

void loop() {
// put your main code here, to run repeatedly:
if (Serial.available() > 0)
{
Serial1.println(Serial.readString());
}
if (Serial1.available() > 0)
{
Serial.println(Serial1.readString());
}
}


Initially, the motor rotates fine and gave me feedback also. But, since last week whenever I gave a command to rotate motor it starts shaking/vibrating. I don't know why? I used same circuit, same power source etc. as I used earlier. I contacted company's people but they are also not getting what the problem is? Using multimeter, I checked voltage and found out 12.9 V which is within the range.

Can anybody help to find out the reason behind these? I have 2 motors and both are showing this behavior.

Thanks.

## 1 Answer

You did not specify how the motor was being controlled. If done through analog, a noisy analog signal could be the smoking gun. If done through some other (I2C or UART) there could be some interruption in the signal.

• I used UART and if there is the interruption in signal then how to remove this? Also, I have another motor same type and that is not vibrating with same circuit and battery power. So, it confuses me a lot. – Naseeb Gill Dec 6 '17 at 6:23
• Sounds like an electromagnetic compatibility or interference issue. Did you or can you check the cables, grounds and signals in detail? – Gürkan Çetin Dec 8 '17 at 19:20