This post maybe a little vague but I'm looking for drive requirements for a DS3225 rc-servo. Has anyone driven the PCM pin of a rc-servo from a 3.3 volt output pin of a microcontroller? The servo gets supplied 5 volts and ground. These servos are cheap enough but there isn't much in the way of documentation.

 

The servo expects a positive TTL pulse every 18mS. The pulse length should very between 1mS and 2mS to give 90 degrees of movement on the servo arm.
It should work with 3.3V pulses.

 

 

Thanks for the reply. My concern is drive current / size of current limit resister for PCM drive.

 

Thanks for the reply. My concern is drive current / size of current limit resister for PCM drive.

I am not sure what you mean. The input of the servo is high impedance. It does not need a current limiting resistor. It can be connected directly to a microcontroller digital output pin.

 

You are confusing two separate requirements.

The drive voltage is between 4 and 6 volts and is supplied to the RED and BROWN cables. The stall current can be as high as 2 A. No current limiting resistor is required.

The PWM control logic signal is supplied between the YELLOW and BROWN cables. The logic LOW voltage is 0 V and logic HIGH voltage is between 3 and 5 V. The current, I am guessing, is less than 5 mA. No current limiting resistor is required.