Thanks in advance for taking the time to read this. We are in the process of trying to create the evaluation circuit for the ADAS1000-4. What we have is a simple custom pcb that exports all the pins off the ADAS to headers.
From these headers we connect to a breadboard with the required capacitors, crystal and power supplies.
The bare minimum (we think) are connected, all AVDD, DVDD and Grounds are connected along with SPI related pins + the crystal to 2 15pF caps. The internal regulator outputs a clean 1.8v to the output pins.
We are using a Intel Curie based board (Genuino 101) and have also tested it with the ATMEGA2560 with exactly the same results.
What doesn't seem to work :
- Using SPI to communicate to the board we read the registers just after reset. the PACE register (exp - 242424) returned 0. However some other registers would return a value other than their reset value (ie 50AJD2) and it would stay constant.
-Looking at Data ready, it changes to busy on bootup for a few seconds but if we reset it data ready goes to 3.3v then drops down to 0 the moment you release the reset.
Finally when trying to turn on the ECG subsystem we sent -
Want: 0010 0100 0010 0100 0010 0100
Got: 0101 0001 0100 0101 0000 0000
All these results are consistent, I am unsure of how best to proceed. Is this because our decoupling capacitors are quite far away from the chip itself (and the crystal) - 10-12cm.
Any tips or hints welcome,
Thank you in advance!