I have a simple setup where Input 2 feeds 7 "General (2nd order)" filters and sends out OUT0. Similarly Input 3 feeds 7 "General (2nd order)" filters and sends out OUT1. The compiler says the instruction count is 16 out of 32.
When I add any additional blocks - which result in an instruction count of 17 or more - audio stops playing out of one of OUT0 or OUT1. Usually OUT1 goes silent.
Is this supposed to happen? Basically I can't use the DSP up to it's maximum 32 instructions.
I've tested all sample rates from 48 kHz up to 768 kHz and the problem is always there.
Ok we figured it out (and it's not documented anywhere).
To access the full 32 instructions:
- increase the "Regulator Control" from 1.1 to 1.2 V
- enable the PLL and ensure the PLL output is 24.576 MHz
- set the "Core Clock" divider to 1
- set the "Main Clock" divider to 2