Quote Originally Posted by modifyit
Does anyone know if the Shiftout command is a software version of SPI and if it can be used to make SPI eeprom and other devices work on microchips that don't specifically have hardware SPI?
Yep. I've used it to communicate with SD cards, ALFAT SD and SPI peripherals without hardware implementation. Pay attention to clock polarity, and if the device validates the data before the clock change,or after. The only down side, besides speed, is you can't shiftin data while you're shifting out. Many devices send data at the same time you are shifting data into them. You will also need to dedicate a pin to select the device before a transfer.