To: BEAM List beam@corp.sgi.com
From: dennison dennlill@buffnet.net
Date: Wed, 17 Feb 1999 15:05:58 -0500
Subject: [alt-beam] No extra chips, Reverse for Bicore photovores
I was thinking, one of the problems that were nasty in building bitbots (or=
bicore photovores) was that it's hard to add reverse to the circuit withou=
t adding a diffrent chip. Here is what looks like the solution to that prob=
lem.
Connect the two motor inputs to the output of a 74Hc245 (your driver chip) =
now, since your using a bicore only one motor input is controlled from the =
bicore. Since the bicore has two outputs. Build your bicore on a 74hc14 so =
you have extra inverters (but not too many!) connect the two remaining moto=
r inputs to two diffrent outputs from some of the extra inverters. Attach t=
o each of the inputs of these inverters one Nu, which will control the reve=
rse time for that motor. Now in normal opperation, the motors both go forwa=
rd. This is because the other inputs of the motors are held low or high mos=
t of the time. so the motor only spins when the output from the bicore is t=
he inverse of the state of the inverter which is holding the line high or l=
ow. So to reverse the motor, toggle the state of the other motor (from high=
to low, or low to high) and now the motor will only spin when the bicore i=
s in the inverse state, and consequentually in the opposite direction.
I know this is hard to get from my language. But I'm working on other stuff=
and I don't have the time to elaborate.
Dennison
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