>-----Original Message-----
>From: pic microcontroller discussion list
>[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of David VanHorn
>Sent: 29 July 2004 17:35
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: Driving long shift registers
>
>
>>     As someone else suggested, I'll mess around with RC
>termination of
>>the clock line. I tried just an R to ground, and that pulled
>the clock
>>too low to drive the shift registers (this whole thing runs on 3V, so
>>the PIC ouput current is a bit limited).
>
>That's why I suggested it.
>No real current requirement, just damps the reflections.
>The 100 ohms is a guess, you could literally stick a pot on it
>and tune for best results.

A low value series R in the clock line at the PIC end may also help to match
the line impedance.

Mike

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