I'm using a Teensy 3.1 along with a SPI based SD card using SDfat and a SPI based OLED display using U8Glib on the same SPI bus (with separate SS/CS lines). So far, each one works by itself, but both together do not work (as I expected.) The display is using software SPI, as I haven't been able to get hardware based SPI to work with it. I think I need to use SPI transactions, but I'm not sure it'll work with the software SPI for the display. I see there is a software SPI version of SDfat. Should I use that, too?