Select the PLL to drive the ToD counter. PLL3 will offer the highest
accuracy time measurement due to the highest ToD clock frequency, however
PLL2 provides slightly longer roll-over times.
PLL3 source is
selected by setting REF0_MISSCLK_VCOSEL to 0.
PLL2 source is
selected by setting REF0_MISSCLK_VCOSEL to 1.
Select GPIO or SPI chip
select as a trigger to capture the ToD counter value to TOD_CNTR field.
Using a GPIO does not require any special timing for the SPI SCS pin. It is
possible to use the GPIO pin for other purposes, then enable the ToD
functionality when required.
GPIO trigger is
selected by setting TOD_CNTR_TRIG to 1.
SPI chip select
trigger is selected by setting TOD_CNTR_TRIG to 0.
Enable the time of day
counter by setting TOD_CNTR_EN to 1.