I designed a hardware with LTC2666 16bit DAC and I want to output some signals by giving the correct commands (I hope). However, When I send command, address and data word, MISO (or SDO) word doesn't match with the previous input (MOSI or SDI) word. It must give previous 32 bit data-word. Therefore analog outputs don't change. I also have a problem with signal level on MISO. I attach the picture at the end.
These are pictures from osciloscope to show all signals.
Green (CH4): MOSI (SDI)
Magenta (CH3): MISO (SDO)
Turkis (CH2): SCK
Orange (CH1): nCS
This is command 0x00A0<some random number>, write code to all, update code all
Current MISO data doesn't match with previous one:
One more strange thing is that the first 16-bit of MISO is always zero.
There is a digital isolator (ISO7763 from TI) between µC and DAC, and MISO signal goes very slowly to 3.3V level after CS signal is released (goes to 1). There is no push-down or pull-up resistors on lines.
Thanks in advance.