An old thread, but the discussion above is exactly where my concern lies.
After reading up (again) on SPI I'm still not clear on difference between CS_pin and SS_PIN.
I'm using the MEGA SPI port (50,51,52) to drive a sparkfun microSD shield
The UNO SPI pins 11,12,13 are re-directed in my design.
The CS_pin is on D8, the microSD default (i.e. SD.begin(CS_pin).
I don't define SS_PIN as it is set to pin53 and an output by the SD library (in sd2PinMap.h) automatically for a MEGA. The SD card is functioning correctly.
But I want to use pin 10 for a non-SD related task (backlight on an LCD) but as soon as SD is accessed the backlight fails.
Why is pin 10 unavailable, when the SS_PIN is 53 on MEGA?
thanks