I'm trying the serial programming of AD9957 (1 GSPS Quadrature Digital Upconverter). it has a simple 2 wire serial interface with protocol shown in attached picture.
for writing to a register the first bit of instruction byte should be 0 and for reading from the same register we should place 1 at that posuition.
i can successfuly read the default values(then I'm sure with the electrical configuration.... ) but i can not write to these places.
any suggestions? any experiences with other similar ICs?! please help,
thanks in advance.
I haven't used that device, but I see a possibly relevant comment on the same page of the datasheet. It may explain why your writes seem ineffective:
"Most of the bits in the register map are not transferred to their internal destinations until assertion of an I/O update, which is not included in the timing diagrams that follow."