We know AD7656-1 can sample 3 simultaneous pairs respectively controlled by CONVSTA(for V1 and V2), CONVSTB(for V3 and V4) and CONVSTC(for V5 and V6).
What we'd like to do is as following time-lines.
step-1. sample V1 and V2 simultaneously by CONVSTA
step-2. sample V3 and V4 simultaneously by CONVSTB
step-3. sample V5 and V6 simultaneously by CONVSTC
step-4. read(output) all of above six data using 3 lines, DOUT A, DOUT B and DOUT C.
We believed above operation must be available, but observed V5 and V6 can read successfully, however V1, V2, V3 and V4 are all zero, despite it must be any positive voltage.
Please let us know whether it is available operation ?
We may need to add some additional step between each control of CONVST, but we do not put RESET there except when start up, since it must smash previous data sampled.
Please let us know how to, or any of your advice and comments would be very much appreciated.