Master clock generator

The master clock generator's PRESCALER register allows adjusting the PDM clock's frequency.

The master clock generator does not add any jitter to the HFCLK source chosen. It is recommended (but not mandatory) to use the Xtal as HFCLK source.

The PDM frequency can be adjusted by using PRESCALER, even while the clock generator is running. The PDM clock frequency CLK = PCLK32M/(2*PRESCALER)

Table 1. Configuration examples

Requested PDM frequency fpdm [Hz]	fsource [Hz]	RATIO	PRESCALER	Actual PDM frequency factual [Hz]	Sample frequency [Hz]	Error [%]
1024000	32000000 (PCLK32M)	64	31	1032258	16129	0.81
1280000	32000000 (PCLK32M)	80	25	1280000	16000	0.0
800000	32000000 (PCLK32M)	50	40	800000	16000	0.0