I have been able to successfully configure AD9548 Evalboard with OCXO mounted and test it through GUI.
Now I am attempting to do SPI communication between AD9548 and an SPI master unit (ARM based SOC). I have some queries regarding the same.
All basic prerequisites for SPI communication are taken care of.
I was able to observe the following:
1. Able to read 'Device Id' from the AD9548 in 3-wire SPI communication.
2. Able to configure AD9548 for 4-wire SPI communication and read default data from various registers of AD9548 in 4-wire mode
3. Able to write data into Active and Buffered registers and read back the same by sending (2 byte) Instruction code & (2 byte) Data as a single 32-bit chunk
4. Able to read default data from registers while sending sending (2 byte) Instruction code & (2 byte) Data as two 16-bit chunks .
5. Unable to write & read back the same by sending (2 byte) Instruction code & (2 byte) Data as two 16-bit chunks. Chip Select is kept low during transfer of all 32 bits in both write and read operations. In the datasheet, there is no such constraint provided.
All the above observations have been verified through Oscilloscope also.
My doubt is that, should every communication happen in 32-bit chunks? Or, am I missing something?