Stranded vs. Solid wire for SPI, I2C

Created Tue, 05 Jun 2012 17:33:27 +0000 by Verdris

Verdris

Tue, 05 Jun 2012 17:33:27 +0000

Hi all,

I'm interfacing a ChipKit UNO32 to an AD7714 via SPI and an AD5175 via I2C. I have a custom PCB that I designed and had printed to hold all the extra electronics. The strange thing is, when I connect the microcontroller and board with solid wire like from a jumper kit, everything works wonderfully. When I sub in a ribbon cable (smaller gauge wire, stranded), nothing works. I get error codes from the AD7714 and the MC won't even see the AD5175. I should note that the ribbon cable is able to power everything sufficiently.

The particular ribbon cable is this: http://www.sparkfun.com/products/10647

However, I've also had this problem with stranded ribbon cable salvaged from an old computer. So what's going on?

jmlynesjr

Wed, 06 Jun 2012 01:30:31 +0000

Possibly cross-talk between the ribbon cable wires. If you have spare wires, try making every other ribbon wire a ground.

James

nik999389

Wed, 06 Jun 2012 15:16:54 +0000

Make sure you have every pin broken out correctly, it gets a little weird plugging those ribbon cables in sometimes. You may have put the wires in the wrong way or they might not be connected to the right pins, check it again.

les1943

Wed, 06 Jun 2012 20:21:39 +0000

If your using IDC headers you may have wires crossed the V on the shell should be used as pin 1 indicator , also home built ribbon / IDC connections can be intermittent and check for shorts at the cut ends.

Verdris

Thu, 07 Jun 2012 16:01:08 +0000

Possibly cross-talk between the ribbon cable wires. If you have spare wires, try making every other ribbon wire a ground. James

This is the advice I've been getting. It's just going to be easier if I do jumper wire, for now.

nik999389

Fri, 08 Jun 2012 14:43:51 +0000

Do you plan to make it an embedded project? Because if the jumper works fine, why not keep it? There's obviously an issue somewhere in the ribbon cable, so i think replacing it with the jumper would be a much wiser opinion.