2019-01-10 03:04 PM
In reference manual table 55 (Kernel clock distribution overview), there is a line for the DFSDM clock, indicating that it can be taken from either sys_ck or bus clock (which in the case of DFSDM would be APB2). That table also indicates that the maximum frequency for that clock is 133 MHz.
My objective is to run sys_ck at 400 MHz and all bus clocks at the maximum frequency they can tolerate (which would otherwise be 200 MHz for APB2), to maximize available CPU power and bus bandwidth.
Does the clock frequency limit on DFSDM kernel clock always apply if the DFSDM is enabled, or does it only apply if that particular kernel clock is selected for CKOUT generation? That is, if I elect to use ACLK for CKOUT instead (by setting DFSDM_CH1CFGR1.CKOUTSRC=1), can I then exceed 133 MHz on APB2? There does not seem to be any mention in the reference manual of the kernel clock being used for anything else other than CKOUT generation.