It's been a while since I've tinkered with the Gerboard and I'm having some doubts about the motor controller. I don't understand what I'm observing so I'd like to ask here before I fry anything (else).
I'm trying to drive a case fan (12V). I have done this successfully in the past with the same Gertboard.
Now however, when I slowly turn up the voltage (variable PSU) I see a current of 0.2A being drawn already at 2V. At this point there is not even any code running, but if I run the motor.c example the effect is the same. The fan itself does not turn, even if I dial it up to 5V / 0.8A. I didn't dare to go any higher.
Some more observations:
- Effect is the same even if the Pi is off
- Effect is the same if I disconnect MotA and MotB, so only have + and GND of the controller connected (tried this only with 2V)
- The fan runs fine directly connected to the PSU (it draws 0.2A at 12V)
- In case it helps:
- I measure ~0 resistance between MOT+ and MOT GNB (shouldn't this be high?)
- ~500 ohm resistance between MOT+ and MOTB
- High resistance between any other combination
a picture of the set up at 2V showing the 0.2A. I'm not sure if the leads are clear but it is connected as follows:- (red) PSU + -> MOT +
- (brown) MOT GND -> PSU -
- (white) MOTA -> fan red wire (-)
- (yellow) MOTB -> fan black wire (+)
GP17 -> MOTB
GP18 -> MOTA
Since I measure the low resistance between MOT+ and MOT GND I assume something is wrong/fried as this is just shorting the PSU...
Did I just do something wrong last time I used the board and the controller is fried? Does this observation make sense in that case? I would think that there would be no current flowing if the controller is fried.
Thanks for any input
