Other Parts Discussed in Thread: ADS1248
I'm having trouble figuring out how to configure the ADS1246 for my application. I have a 5-channel round robin on an external multiplexer that I'd like to measure, with the PGA set to 4x for the first 4 channels and 1x for the 5th. I'm looking for the simplest answer that should work.
What I think should work is:
- Set START high and leave it there forever
- Send 0x4A 00 08 to activate DOUT/DRDY mode.
- LOOP: Set the multiplexer to a channel
- Drop CS, send either 0x43 00 20 (for the 4x channels) or 0x43 00 00 (for the 1x channel), raise CS.
- Drop CS, send 0x04 to restart conversion, raise CS
- Drop CS, which should cause DOUT to go high.
- 200ms after that SYNC command DOUT should go low to indicate that the conversion is ready.
- Send 0xFF FF FF FF while reading in the conversion result. DOUT should provide results during the 3 and go high on the 4th.
- Go back to LOOP
What I'm getting is wildly inconstant ADC readings on signals that should be largely stationary. Am I just grossly misunderstanding how to use this chip?