I ran into a very strange problem this weekend.
I made an extension board for engine data logging with a DS1307, analog inputs for pressure, 2 rpm counters and an sdcard on it, all working very well for the last year.
This week I build one for a friends tractor puller but with an Mega instead of an UNO, due to I2C and SPI pin differences I am using softI2C and softSPI on the Mega for that, no problem also that is working very well.
For temperatures I use another board, the KTA-259 http://oceancontrols.com.au/KTA-259.html
which also uses SPI placed on top.
On the UNO all is working very well but on the Mega the moment I add the KTA board the sdcard is failing, nomather how or what I initialize first or not at all, when the KTA board is plugged in sd card stops working.
My pin layout is as follows:
9 - CS -> KTA259
10 - SS -> sdcard
11 - MOSI -> sdcard
12 - MISO -> sdcard + KTA259
13 - SCK -> sdcard + KTA259
The only thing I can think of is that the KTA-259 is somehow blocking either or both pins 12 & 13 but have no idea how or why, maybe someone over here can shine some light on this?
p.s. It is not code/lib related since all parts separately work with the code, the moment I add the KTA board it looks like the sdcard pins are "stolen" or interfered in some way...