I've been scratching my head on this one for quite some time, and maybe someone can shed some light on this. I have an AD7705 16-Bit BiPolar Dual Channel Analog to Digital converter, which I am trying to incorporate into a prototype that I am building as part of my water meter project. Initial prototype on breadboard worked wonderfully, and there are posts about it on
www.venturii.net. I've been building a perf board version, to make the circuitry a little more firm and to incorporate numerous other circuits and supporting gear as a firmware-proving platform. Out of curiosity, rather than any sort of necessity, I moved the chip select pin off of pin 10 and onto pin 4. In the AD7705 library there are static declarations for MISO, MOSI, CLK and Chip Select pins, and I changed the Chip Select pin designation from 10 to 4. No go. No matter what I tried, it would not work in this configuration, but if I choose pin 10 (and adjust wiring accordingly) it works perfectly. I've read posts on the Arduino forum and others where people have insisted that they've been able to get this to work, some claiming that you have to set the pin as an output before calling the SPI functions, which this library does, yet no matter what I've tried, it does not work on anything but pin 10.
As I said, this is fine on this project, I can use pin 10, I am just wondering if there is some way to use other pins for chip select (and have it actually work) as I've never been able to accomplish this seemingly simple and documented possible task.
