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RaeEversmann / Board2013

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Motor controller pull-ups #2

Open weng-frank opened 11 years ago

weng-frank commented 11 years ago

Either remove the pull-ups on the IN1 line on the motor controllers or add a pull-up to the IN2 line also. I actually recommend pull-ups on both, although removing is going to be simple to deal with in software.

cmonr commented 11 years ago

So the original purpose of the pullups was to put the motor controller in brake mode while being programmed, and while the IO pins were not initialized.

Neither boards have been tested for this effect, and I have a strong hunch that both boards will fail when being powered by USB only, regardless of the pullups.

In leiu of this, I want to suggest something in addition. Remove the pullup resistors, but also add a diode from the 5V line coming from the switching regulator going into VBUS. When the USB is plugged in, there will be no power flowing into the BoosterPack, as it should be. When the battery is plugged in, there will be a slight voltage drop in the 5v line going into the 3.3v regulator, but it will still work. When both are plugged in, the USB voltage will be dominant over the slightly lower 5v from the switching regulator, but the diode will make sure that nothing bad happens.

I will attempt to test this on my board Sunday.

robz commented 11 years ago

Out of curiosity @cmonr did you get a chance to test that?

cmonr commented 11 years ago

I have not. I've only been to the Bunker once this past week, and forgot to pickup a Diode. I'll stop by and get it tested out this weekend. Likely Saturday.

cmonr commented 11 years ago

@robz http://www.youtube.com/watch?v=T2BNmn8TYdE Diode works :+1:

robz commented 11 years ago

whosawesome