Q
I am able to read and write single-byte registers but the output is not updated when I write a word to the DAC register.
A
The AD3552R is configured in address decrementing mode by default. When addressing a multi-byte register, the address of the MSB must be provided, and data must be written starting with the MSB.
For example, to write CH0_DAC_16B register, the SPI transaction must start with address 0x2A, followed by MSB data and then LSB data. Bit ordering is always from MSb to LSb.
| Address | CH0_DAC_16B |
| 0x29 | CH0_DAC_16B [7:0] |
| 0x2A | CH0_DAC_16B [15:8] |
The addressing mode can be changed but DAC registers must be accessed in decrementing mode always.