controlling universal motor interface with raspberry pi GPIO

[jayekub]

i just ordered the universal control interface kit (http://rollertrol.com/store/en/motor-control-kits-for-home-automation-systems/58-home-automation-systems-motor-control-starter-kit.html), and i'm looking into controlling it via a raspberry pi.

my knowledge of electronics is a bit limited, so i'm not totally clear on how to reliably and safely control things. the universal interface info page (http://rollertrol.com/universal-DC-motor-interface-for-motorized-blinds-shades) says that it needs "switch closures" for control, which i'm interpretting to mean connecting one of the control pins to GND. i'm pretty sure i can do this with the pi's GPIO pins by outputting a low signal, but then i'm not sure what sort of voltage/current the pi will have to sink from the universal interface board? i feel like i saw something about 5v somewhere, although i can't find it now...i'm pretty sure asking the 3.3V GPIO pins to sink 5V isn't a good idea, right? if so i'll probably need to control a transistor with the GPIO pins, and use the transistor to connect the interface's header pins to GND?

thanks for any info!

[admin]

Hi @jayekub, thanks  for your message.

You hit the nail on the head, you should not try to activate the controller directly with a GPIO port, it will require an intermediate transistor.

The controller works by pulling the appropriate pin to ground, you can test this simply by attaching a piece of wire to the controller header and touching the ground pin.

If you are operating it in 'momentary' mode, if you short the OPEN pin to ground, it will cause the motor to operate in one direction until you release the ground contact (unless it has already reached your pre-programmed travel limit).

Your unit has already been shipped, and I will be sending you further instructions shortly.

If I can be of further assistance, please contact me any time.

Regards, Adrian

Adrian Biffen
Customer Service
RollerTrol Automation Systems
http://RollerTrol.com

[jayekub]

great, thanks for the info!