I've used all the available pins on the expansion headers of the Xplained board. This little board now controls 3 DDS oscillators, a 4-line by 20 character OLED display, an optical encoder, a multi-function menu switch, and 3 relay boards (14 band-pass filters, 4 crystal filters, and demodulation selection: AM or sideband). I need one more pin to control another relay board, and I think I will have the project finished. I've already cut the DISPLAY_RS trace and using that I/O pin (PD0).
I'd like to use PD2 pin as the new relay board select line. The documentation states that this pin is used for Display and serial flash MISO input. However, I'm not using the FSTN display, nor am I using the AT45DB642D DataFlash device, just the flash and SRAM memory in the XMEGA256A3BU device. Is there any downside to using this pin for output only? I don't want to disable the JTAG to use one of the PB4-PB7 pins.
Any thoughts out there on the ability to using the serial flash control lines (PD1 - PD3) as I/O (in this case, output only)?
Thanks for looking,