Re: Design considerations for (2m) long signal lines

On 18/07/2007 Peter S. May wrote:

I'm working on a microcontrolled LED lighting setup in which breakout
boards with eight outputs each would be connected to the
microcontroller board by cables (CAT-5 is what's on hand) at a length
of somewhere between 1m and 3m. The breakout boards would contain
some sort of D-type flip-flop or latched parallel-out shift register
with outputs connected to transistors that then drive the LEDs.
Using a shift register would have three signal lines (signal, shift
clock, latch clock) and two supply lines.

I need sort of a run-down of the design considerations I need to
account for, and I'm not sure where to look. Are decoupling
capacitors (say, .1uF) going to be enough to keep the ground stable?
Will putting Schmitt triggers on all the input signal lines of the
breakout boards help? Without resorting to differential signaling,
what limits will I run into for the data rate? Will a long cable
make a significant addition to propagation delay?

Thanks in advance for any insight...
PSM

Sounds like a job for RS485 drivers and receivers. Look for MAX485 and
equivalents.

--
John B
.

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