9.3.9.6.2 Swap Flag

The swap flag is used to copy the audio coefficient from the host memory to the DSP memory. The swap flag feature is important to maintain the stability of the BQs. A BQ is a closed-loop system with 5 coefficients. To avoid instability in the BQ in an update transition between two different filters, update all five parameters within one audio sample. The internal swap flag insures all 5 coefficients for each filter are transferred from host memory to DSP memory occurs within an audio sample. The swap flag stays high until the full host buffer is transferred to DSP memory. Updates to the Host buffer should not be made while the swap flag is high.

All writes to book 0x8C from page 0x11 and register 0x58 through page 0x21 and register 0x78 require the swap flag. The swap flag is located in book 0x8C, page 0x23, and register 0x14 and must be set to 0x00 00 00 01 for a swap.