On Fri, Feb 17, 2006 at 07:31:09PM +0000, Sergey Dryga wrote:
> > I'll place an order in the next day or two, meanwhile, anything I should
> > know about these supplies? I assume with my application I should be able
> > to simply hook them up and be done with it. Looks like they all have
> > overcurrent protection, so no fuses needed. I don't see any mention of
> > filter caps or such in the datasheet, so I assume they are relatively
> > foolproof other than making sure they can still get airflow.
> > 
> 
> If I remember correctly, in current configuartion PIC voltage is supplied form 
> the same power bus as motors.  This might cause glitches and random "reset" of 
> the PIC.  If you see some random problem, consider making a separate regulator 
> just for PIC.

The motors are pretty small ones, and in previous testing things seem to
be ok. That said, I did find out that a swift turn of the knobs they are
attached too generates enough back-EMF to reset the individual PIC on
the single motor control board. Unfortunately everything is connected to
an I2C bus, so this invaribly crashes the whole bus. Interestingly the
watchdog timer on the PIC fails too.

Note that I did connect the the motor leads directly to the PIC ADC
inputs, so there is a pretty direct route to the PIC. I have a ULN2000
driving the motor, and I thought the inherent protection diodes in it
would help... It worked on the breadboard, but the full circuit on a PCB
didn't. Oh well, my current plan is to turn the whole shebang of motors
on and off via FETs in series with v+ whenever the bus gets stuck.

The other bit of weirdness is related to my bootloader setup... If have
the master controller reflash the slaves on startup everything works
fine. If I tell it to skip the reflash, and rely on what's already
flashed, one or two out of the 64 slaves will fail to recieve any
commands from I2C. Very odd, and which slaves fail to work changes on
each reflash.  I've got a lot of debugging to figure out on that one...

-- 
pete@petertodd.ca http://www.petertodd.ca
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