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.
Details
Schematics and layout files will be provided at a later point in time.
Software interfacing through the spidev interface.
Not sure it's quite the same thing, this project looks to be capable of *real-time* D->A (and A->D?), whereas sdramThing is much more about sample/repeat of a lot of data in bursts.
However, you got me thinking... maybe it doesn't need to be limited to AVRs, maybe even an RPi, hmm... Thanks, yo!
But they are limited to 1MS/S and have a goal of making a scope. Your sdram thing would make it a two step process: 1. Capture the analog data into the sdram at max speed (like 20-30MHz) then 2. slowly pull it out into the Pi at e.g. 1MHz and display it.
See @esot.eric's SDRAM thing project.