SPI to TFT distance

[Wp100]

Hi,

Am looking to drive a TFT screen , probably from an Ardunios SPI lines, but would like to have the screen remote from main control board.

I know SPI is supposed to be an onboard connection only but wondered if anyone has found a short cable still works ok eg 250-500mm or even up to 1000mm ? ( don't want to add line drivers etc)

thanks

 

[Nigel Goodwin]

For my PIC tutorials I use Molex 10 pin connectors on the boards, and join the boards using leads about 300mm long - these work perfectly fine with SPI - but I've never had any reason to try (or even make) longer ones.

I'd suggest you give it a try and see how it works - assuming you use pluggable leads, you could try a short one (to make sure everything works) and then try it with a longer one. I wouldn't have though 500mm would be a problem, as 300 is perfect. If you do start to have problems, you could always reduce the SPI clock frequency a bit.

 

[ronsimpson]

even up to 1000mm

When I needed to do this: I used ribbon cable with every other wire as ground. gnd, clock, gnd, data, gnd, power, gnd
I also terminated in 100 ohms to match the cable impedance. (long run)

I think in your case of only 1m you can not terminate, but you should use a bundle of wire not loose wires. You might have to back the speed down a little. 10mhz might be a problem.

Repeating Nigel "try". You might try 2m to say 1m will work.

 

[dknguyen]

Speed really matters.

 

[Wp100]

Thanks all, worth giving it a try then, won't be more than 1 mtr away and will use a multicored braided screen cable to connect so it also looks neat.

 

[dknguyen]

Thanks all, worth giving it a try then, won't be more than 1 mtr away and will use a multicored braided screen cable to connect so it also looks neat.

Check the cable datasheet and terminate it according to the impedance.