nRF clock control
Demonstrates how to request minimum clock requirements of nordic clocks, including getting the startup time to ensure clock requirements are met in time.
Requirements
Requires an nRF54H20 based board.
Building, Flashing and Running
The sample is built to test a specific clock requirement for a specific clock. The clock is specified in a devicetree overlay, and the clock requirement is defined using these sample specific Kconfigs:
CONFIG_SAMPLE_CLOCK_FREQUENCY_HZCONFIG_SAMPLE_CLOCK_ACCURACY_PPMCONFIG_SAMPLE_CLOCK_PRECISION
With the following controlling how long the request is held:
CONFIG_SAMPLE_PRE_REQUEST_TIMEOUTCONFIG_SAMPLE_KEEP_REQUEST_TIMEOUT
Example configs and overlays are added for every clock, which can be found in sample.yaml,
and applied using the -T west argument. The following example builds the sample to test the
FLL16M:
west build -b nrf54h20dk/nrf54h20/cpuapp -T sample.boards.nrf.clock_control.fll16m samples/boards/nordic/clock_control
Example output:
clock name: fll16m
minimum frequency request: 0Hz
minimum accuracy request: 30PPM
minimum precision request: 0
resolved frequency request: 16000000Hz
resolved accuracy request: 30PPM
resolved precision request: 0
startup time for requested spec: 850us
requesting minimum clock specs
request applied to clock in 1ms
releasing requested clock specs
clock spec request released