at the moment I am experimenting with using 2 PSRAMs with T4.1 for audio processing (guitar cabinet impulse - partitioned convolution filtering).
However, it seems the PSRAM is too slow for large filters. (I use TD1.52 beta-5 and the fix in startup.c to adjust for 88MHz PSRAM speed: or is that only the speed for FLASH?)
So I tried to increase the speed in startup.c, but I do not understand the syntax correctly:
* CCM_CBCMR_FLEXSPI2_PODF is the divider
* but what is the reference frequency that is divided?
* CCM_CBCMR_FLEXSPI2_CLK_SEL : this selects the clock, but which one should I use
Sorry for my non-existent knowledge of fundamental clock management in the T4.x, but how can I calculate the speed of the PSRAM
this setting below speeds up things a lot, but obviously I do not know what I am doing here . . . and I have not yet attached ADC/DAC, so I do not know whether the PSRAM really works properly at this kind of speed.
Code:
// turn on clock (TODO: increase clock speed later, slow & cautious for first release)
CCM_CBCMR = (CCM_CBCMR & ~(CCM_CBCMR_FLEXSPI2_PODF_MASK | CCM_CBCMR_FLEXSPI2_CLK_SEL_MASK))
| CCM_CBCMR_FLEXSPI2_PODF(1) | CCM_CBCMR_FLEXSPI2_CLK_SEL(0); // much faster than allowed??