I’m wondering what can be the max length of the gadgeteer cable without incurring in transmission issues.
Mainly for SPI sockets.
Ciao
@ AlbeNET - It’s pretty much impossible to tell without getting specific requirements. For example, I once used (very briefly) ~20m of unshielded and untwisted cables for I2C comms, and it was kind of working at speeds of 1kHz or so, but was very unstable and I had to retransmit data very often.
In general, I think, it’s a couple meters that you can still do things reliably. Anything above that — and you’re asking for trouble, and the higher the frequencies, the sooner the trouble arrives…
The signal reliability will depend on the length of cable, the speed your signals are running, and the environmental aspects.
You could improve your chances if you made your own cables - the standard flat Gadgeteer cables are not going to give you the best results. I can’t remember where I read it, but using Ethernet UTP can greatly help, use each pair as a signal wire and a ground wire. You also have to remember you’re going to get voltage drop, unless you can find unobtanium cables with zero resistance, so the SPI device on the end of the line still needs to recognize those muted signal levels and the same with the mainboard. I’d start by testing a setup over the length you need, and if you don’t get reliable results start dropping the frequency to see if you can improve it
Right!
Thanks to everybody!