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Trouble getting servo and dc motors to work with adafruit 16 channel pwm controller on raspberry pi

tlucas756

Hello everyone,

I need to get a servo motor and a DC motor of an RC car to work via pwm using a javascript app on my raspberry pi, which takes my phone's gyroscope coordinates in order to change the speed and direction of those motors.

The app does register the phone's movement, however, the motors do not move at all.

What can I do to fix this? this is fairly urgent, so any help at all is appreciated!

the files were copied from the site http://github.com/shaunuk/picar and are as follows:

pwm_test2 is the configuration file for the motors.

README.md is the instructions file I was using

socket.html is the html file that is launched, and I think its code plays a role in driving the motors.

The images are how I connected my Pi to the controller, and how I connected the controller to the servo and the DC motor.

This project was based on shaunuk's project: http://github.com/shaunuk/picar

Thank you!



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  • I take it that you managed to swap the DC steer motor for a servo in the end ?

     

    First off you will need to connect a power supply to your servo motor and the DC motor. Your wiring diagram shows that you have connected VCC to the R-Pi, which will power the motor controller logic but not the motors.

    The motors will require a separate power supply connecting to the V+ rail.

     

    Secondly as previously mentioned, you are not controlling the speed motor by PWM with this setup - you have just wired it directly to the +V power rail so it will go full speed forwards as soon as you connect the battery to it.

     

    The original project used a r/c ESC (electronic speed control) between the R-Pi and the speed motor. You need to do the same between your Adafruit clone PWM controller board and the speed motor in order to control it via PWM.

     

    Thirdly, the original project controlled the PWM directly from the R-Pi and not from an external I2C interface motor controller board. You will require to re-write the original code so that it sends the control signals over the I2C bus to the Adafruit clone motor controller interface.

     

    Fourthly, you will need to enable the I2C interface on your Pi before you can communicate with the PWM interface.

     

    Finally, perhaps take a look at the Adafruit tutorials on using the PWM interface:

    https://learn.adafruit.com/adafruit-16-channel-servo-driver-with-raspberry-pi

    https://learn.adafruit.com/16-channel-pwm-servo-driver