Whew!!

Finally got somewhere with this project.

I've now got a PIC16F877 talking to another PIC16F877 over a radio link.

The first PIC monitors steering and throttle positions from the virtual
car, plus some other stuff and relays all the info to the other 877.

This then tells two 12C672's to move the real thing via some rather
large servos.

I just blew a 10A fuse trying to do a quick steering direction change,
but I noticed the motor manufacturer specified up to 20A when this
happens, so maybe a 30A fuse is needed. The motor is braked when told to
stop or change direction, so I may have to put in a bigger dead time as
well. It's pretty hairy the first time you apply power to these things
considering the power behind them and not exactly knowing what's going
to happen. You can take all the precautions in the world, but there's
always some little thing you forgot :-)

Still,  it's somewhat gratifying to know the darn thing works thus far.
The MOSFETs didn't even get warm during fairly hard testing.

I was a little bit worried how the PIC would perform being on the same
PCB as the power drivers, but it seems to handle things ok. It uses a
seperate power supply and controls the power section via opto couplers.

One interesting thing. The MOSFETs are rated at around 70A, but the
leads look smaller than a 7805 regulator. I wonder if thay could
actually carry that amount of current.

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Best regards

Tony

http://www.picnpoke.com
mailto:sales@picnpoke.com