Question When I set test data register though SPI interface- I select one zero word toggle- I observe following sequence:FFFF 0000 FFFF 0000 0000 FFFF 0000 FFFF and it repeats as such. What is the sequence that I should observe by using this setup. Answer Refer AN-77: http://www.analog.com/media/en/technical-documentation/application-notes/56755538964965031881813AN_877.pdf In the Table 8, based on SPI write, it is specified what would you get as the output. when you are writing in the register Output Test Modes (0x00D) .