AD7656 16 bit ADC

AD7606_sm.jpgAnalog Devices AD7656 - 6 Channel 250ksps 16 bit A/D converter.

This is a nice part that I ordered long enough ago that it's been superceded by the somewhat easier-to-use AD7606, but I'd soldered it to the breakout board (using solder paste, a stencil, and an electric skillet) and I finaly got around to firing it up. I'd like to develop an open design around it for labs who really can't afford a comparable commercial multi-channel acquisition card. It hasn't been a major priority in my work so far (in other words, I don't need it to measure something yet), so I've just been hacking around with it in my spare time.

system_sm.jpg

Connected to Arduino and DC-DC converter.

To start with, I've just hooked it up to an Arduino and used a Murata DC-DC converter with LC filtering to generate +/-12V rails from the Arduino's 5V line. It's alive and working fine. Basic Arduino code can be found here: basic_AD7656_acq.pde on GitHub

SPI_sm.jpg

Happily clocking out data.

The raw transfers are pretty fast, though I haven't pushed it out to the part limit. The transfer to the computer is slow. I can do 100Hz or 200Hz sample rate without drops or errors just using an Arduino, which would be fine for many applications, but is pretty bad overall. Work in progress.