I am currently writing code for controlling an ADAU1442 DSP, and have had no luck finding detailed documentation describing the various registers. I've found documentation of the basic fixed point formats used, but nothing describing the function, valid range, units, or any special values of the various register settings. Is there more complete documentation somewhere?
I did find a document describing the fixed point and integer formats, which throws out one confusing mention that 8388608 (that is, 1 << 23) is "0 dB full scale represented in 28.0 format". I'm interpreting that to mean that the value 8388608 in the 28.0 format is 1 in the 5.23 format, and that parameters and signals are represented as linear values, not logarithmic...gain parameters, for example, would be simple multipliers in 5.23 fixed point format, not decibels. Is this correct?