Both the servo and DAC builds use the Adafruit I2C library and a bit of Python. Of course it’s possible to treat the GPIO pins on the Raspberry Pi as digital outs, just as [Mikey] did with his ...

Using an Adafruit FONA 800 shield, Adafruit TFT Shield w/Resistive touch, and an Arduino Uno developer board, along with a few other components, it’s possible to create your very own mobile phone.