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Interface a microcontroller directly with a servo motor 900-00005 — Parallax Forums

Interface a microcontroller directly with a servo motor 900-00005


I'm working with an arduino nucleo board (NUCLEO-F446RE ), and I would like to control servo motors (parallax 900-00005) with it. The microcontroller has PWM outputs.

I would like to check if I can connect "directly" the motor to the outpout pins of my microcontroller without damage it. By "direclty" I mean use a bredboard, not solder wires on pins directly, but don't put any components between microcontroller and motors.

I found on the internet that it's generally not recommand to connect directly motors and microcontrollers.

In the datasheet of the 900-00005, it' written :
- "Easy to interface with any Parallax microcontroller or PWM-capable device" + the schematic at the begining of the page 2 => you can connect direclty
- "Do not try to power this servo directly from a BASIC Stamp module's or any microcontroller’s Vdd or Vin pins; do not connect the servo's Vss line directly to the BASIC Stamp module's or any microcontroller’s Vss pin." => you can't

I think the question is not extremly technical, but I'm a little bit perplexed, could you please help me?


  • Ok, when using the servo with a load attached it can draw a lot of power. If you just have it sitting on your desktop with nothing attached it will work fine from the 5v source. Motors produce current spikes as they startup and can destroy some power supplies. The more load the bigger the spike.


  • kwinnkwinn Posts: 8,687
    If you look at page 2 of the Servo Motor manual/data sheet you will see a diagram of how to connect the servo motor to the microcontroller. Recommend that you follow the suggestions below.

    1 - Do not power the servo motor and microcontroller from the same power supply.
    2 - The servo motor and microcontroller power supply grounds (black wire) must be connected together.
    3 - The Arduino is typically powered by a +5V supply.
    4 - The servo motor should be powered from a 5 to 6 volt power supply.
    5 - The I/O pin from the Arduino can be connected directly to the servo input (white wire).
  • Thank you iseries and kwinn for your help ! I know what I have to do now ;)
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