I am trying to configure the AD9826 to run in SHA mode by changing the configuration register bits. All configuration registers bits except for D4 (selecting SHA or CDA mode) can be written, but D4 can not be set to 0, which would set it to SHA mode.
The circuit is currently configured to run in CDA mode. I am aware the circuit needs to be adopted for the SHA mode but would have expected to be able to write the configuration bit. Is the wrong circuit configuration (i.e. CDSCLK not connected to GND but to a clock signal) the reason that the configuration register can not be written or is there another problem?