Hi,
I've run into a very interesting problem, and I've spent the past few days debugging. Still no solution. May be you guys could help?
I have two rigs based on the ADS1292R - one is a prototype rig based off a Shmartboard with wires all over, the other is a PCB version of it. They are identical in terms of schematic, but one works and the other's MISO never replies correctly. I've swapped chips from both rigs, and still same behavior. It's most definitely a problem with hardware on the PCB, but I can't find any difference between the two boards!
Here's my schematic : 
Specifically here is the one that doesn't work. Notice that the MISO reacts to CS correctly ( same way as my other rig) : it goes high when CS is disabled, then low when its enabled. This is zoomed out a bit, if I zoom in I can see the individual data transmission and it looks good. I'm running SPI at 1MHz, and like I said it works perfectly and I can read registers and use the chip just fine on the other rig.
I've verified that all the pins are getting the right signals, and that power connection is all correct. PWDN is High as it should be.
I noticed in a schematic online that the CLKSEL pin was pulled up with a 10k resistor. I have a direct connection to 3.3V, no pull-up resistor. I've verified the voltage on CLKSEL with a multimeter. My far fetched theory now is that I need a pullup on the CLKSEL, and the only reason it worked on the prototype board was that I used wires ( which have a bit of internal resistance). Think this would hold? I don't want to try it ( It involves messing up the PCB) unless it holds some water.
What sort of hardware issue makes MISO react to CS but not send data?
Thanks for your time.
