This project adds a 2-channel A/D converter and a 2-channel D/A-converter to the Raspberry Pi using the SPI interface, achieving up to 1 MSamp/s conversion rate. This enables the use as a digital scope as well as hooking up a transceiver to turn the RPi into an SDR.
Schematics and layout files will be provided at a later point in time.
Software interfacing through the spidev interface.
See @esot.eric's SDRAM thing project.