🚀 go-pugleaf

     -=> Lee Hounshell spoke of "Re: miniboard 2.0 - i nee" <=-
    To All at 09-02-92  23:34
 LH> Fred, thank you very much for your suggestions.
 LH> Of the two alternatives you outlined, I think I prefer the 2nd the
 LH> best (register shifting).  It offers much better use of the miniboard
 LH> and is far more space efficient.  The only thing that worries me a
 LH> little is the random motor motion that might occur during the shifting
 LH> of registers. Nevertheless, at the moment I am leaning toward this a
 LH> the solution I will implement.

You might be able to "fix" this by using serial to parallel chips
with tristate outputs and by straping the outputs to ground via a
resister network.  This way you can drive the outputs when your
not shifting then activate them when your done.  Assumeing that
your inputs to the motor controller are active high of course.

The 74ls164 is an 8bit TTL SIPO register but has no control of the
outputs so you would need a tristate buffer attached to the
outputs of each one.  Since you can chain these and have them on
seperate boards it's no big deal.  this means 1 14 pin chip and 1
74ls241 20 pin for the 8bit 3 state buffer.  These are relatively
inexpensive about $0.49 for the 164 and 0.69 for the 241.

However if you want a single chip solution try the CMOS part
4094!  This beauty has everything built in 8 bit SIPO shift
register a storage register and a 3state output buffer.  The
advantage is that you can select whether you want to store the
data or not in the register and also enable the output.  You
might have some TTL to CMOS conversion needed but if you need
space reduction this is your chip since it's only 16 pin [small].
This chip costs about $1.19 so it's cheaper and smaller and uses
less power.  Howver if you need TTL drive you might have to go to
the former.

 LH> Do you know of any way I might "disable" all the motors while the
 LH> registers are being shifted into place?

Read the above.

 LH> Also, is anyone working on (or planning on building) a monitor program
 LH> that will enable the miniboard to be networked to other miniboards?
 LH> Perhaps we could make this a net project if the interest level is high
 LH> enough.

        Stephen Cyberman@Toz.Buffalo.NY.US
        Scripted at Fri  09-04-1992  10:43:30

... Sorry, you have to think to use a computer.
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