il_diavolo
Posts: 139
Joined: Mon Dec 02, 2013 7:56 pm

Motor controller defunct?

Fri Jan 24, 2014 3:57 pm

Before I start, yes, I do have the jumper on J7 installed.

I set up a small motor connected to the terminal block, together with an external 3v power supply, all as described in the manual. (The motor works when connected directly to the batteries.)

When I run either "motor" or "potmotor" (in C or Python), neither activates the motor. After another look at the manual I tried connecting 3.3v and ground (from Gertboard pins) directly to the pins Mot A and Mot B in J5. Table 3 in the manual indicates that this should produce a rotating motor. My multimeter stubbornly reads 0v between the Mot A and Mot B output terminals whatever I try.

Connecting my motor/battery setup to the open collectors, running "ocol", everything works properly.

Can I conclude from this that the motor controller is dead? Or am I missing something?
Colin

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joan
Posts: 14472
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: Motor controller defunct?

Fri Jan 24, 2014 4:48 pm

Check the manual. I thought the Gertboard only supported motors of more than something like 7 volts.

il_diavolo
Posts: 139
Joined: Mon Dec 02, 2013 7:56 pm

Re: Motor controller defunct?

Fri Jan 24, 2014 7:30 pm

I could be wrong but I don't think the motor supply voltage is the problem. The manual says "The motor controller is for brushed DC motors and can handle a maximum voltage of 18V and a max current of 2A". Later - "The motor will probably (not definitely) need more power (a higher voltage or current) than that provided by the Gertboard."

I tried it with 4.5V as well as 3V but still no response. I am wondering if the internal temperature "thingy" in the controller needs resetting somehow. A long shot, as far as I know it has not got hotter than ambient. Is there definitive test for checking the controller, everything else on the board works as it should.

il_diavolo
Posts: 139
Joined: Mon Dec 02, 2013 7:56 pm

Re: Motor controller defunct?

Sun Jan 26, 2014 10:09 am

Phew! Saved from embarrassment by Forum problems!
Yes, the data sheet for the controller shows a minimum voltage of 6V.
Apologies and thanks to all who replied. I achieved success with 7.5V (my 3V and 4.5V battery packs wired in series).

A case of RTFM :) :mrgreen:

Colin
Using Linux since January 3rd 2014

electronicman
Posts: 30
Joined: Mon Dec 10, 2012 9:31 pm
Location: USA

Re: Motor controller defunct?

Fri Jan 31, 2014 1:28 am

Be careful with the voltage, the maximum voltage for the controller is quoted at 18 Volts DC and they mean 18 volts, as I found out much to my chagrin.
David

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