Select the PLL to drive the Time Elapsed Counter
(TEC). PLL3 will offer the highest accuracy time measurement due to the highest TEC
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 TEC counter value to TEC_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 TEC functionality when required.
GPIO trigger is selected by setting
TEC_CNTR_TRIG to 1.
SPI chip select trigger is selected
by setting TEC_CNTR_TRIG to 0.
Enable the TEC counter by setting TEC_CNTR_EN to
1.