next topic »

[on:]

What is the  limitation in distance between daisy chained TLC's 5940? I am trying to connect 15 chips with ethernet cables of various lenths up to 6 meters, so the total distance between 1st and last chip in the chain is about 18 meters. I am not sure if the problem is distance, choice of cable, or both. But everything works fine with short cables. I used the library from http://code.google.com/p/tlc5940arduino/
Thanks forum

[Reply #1 on:]

Yes 18 meters is way too far for this. About 2 meters in total I would say is the limit.

[Reply #2 on:]

I did achieve the distance of  max 3.5 meters between Arduino and single TLC without any problem, but when more chips are daisy chained, than indeed 2 meters in total seem to be the maximum. I guess i will have to extend the connection between chip and leds instad, and see if i can reach the total length.

[Reply #3 on:]

I guess i will have to extend the connection between chip and leds instad, and see if i can reach the total length.

That can lead to problems as well.
See my Hexome project where that happened.
http://www.thebox.myzen.co.uk/Hardware/Hexome.html

You could try buffering the signal between each board. Something like a pair of 74LS04 buffers on each board to drive the chip and boost it on to the next distant TLC. You get 6 buffers in one chip but they are inverting buffers so you should be able to cope with the three lines with one 04 per TLC.