DAC Command register read test:
Read:  $55  $AA  $5A  $A5
  0    55   AA   5A   A5
  1    55   AA   5A   A5
  2    55   AA   5A   A5
  3    55   AA   5A   A5
  4    00   00   00   00
  5    55   AA   5A   A5
  6    55   AA   5A   A5
  7    55   AA   5A   A5
  8    55   AA   5A   A5
  9    00   00   00   00

Dac Single Bit Mask: FF

DAC mask: FDh R/W: FDh Chg: FD Set: 00h Clear: 02h