Basically, what are the ratings for the Ground GPIO pins? I guess nothing above 5 Volts and 1 Amp, but knowing what they are would be helpful (for a similar project I am planning to do when I have time later).
I wanted to know anyway, but the other reason is that I want to do this:
I am finishing off my Raspberry Pi powered robot, now based on an old Cybot base, which has motors, and a motor controller.
There is a detailed schematic with lots of info on the motor driver board here - here is is a modified copy (It should say left motor and right motor, but I can't be bothered to change one the 'right's):
Here is also a schematic for a Arduino board:
I have successfully powered ONE of these motors, not using the motor controller circuit, a TIP31C NPN transistor - which was being controlled by a GPIO on Pi through a a 1K resistor- the motor being powered by 6 Volts, and the grounds of both circuits connected.
With four GPIOs, I should be able to connect to the first 4 pins of the motor controller (which contains 1K resistors on the input anyway), and then connect the last pin of it to the Ground of the Raspberry Pi - but can I do this without putting too much on the Pi? - I guess not, but I currently have only the one (working) Pi?, and I don't really want to blow it up.
In other words, what are the ratings for the ground on the Pi? (Voltage, Current etc). Searching does not seem to find anything.
Any corrections welcome.
When I get around to testing it, I may provide the results as an answer - this could be used for reference anyway.
It is now working, though I still have a problem with a dodgy connector . You do need to connect the grounds by the way.