JAJSN00 September 2022 LMK5B33414
PRODUCTION DATA
The Time Elapsed Counter (TEC) allows the user to make a precise time measurement between two (or more) events. The events may be either a rising or falling edge of a GPIO pin or a falling edge of the SPI SCS pin. Any GPIO pin can be programmed for TEC input. Rising or falling polarity can be chosen using the GPIO polarity invert register. After each TEC event, the counter values is captured and the application may read back a 40-bit value. The elapsed time is calculated based on the difference in the read back values. The accuracy of the measurement is better than 7.5 ns with a total measurement time over 59 minutes depending on exact configuration. It is necessary to read back at least the LSB of the TEC_CNTR to re-arm the TEC counter capture.
The TEC counter is clocked at a frequency based on PLL3 VCO frequency ÷8 or PLL2 VCO frequency ÷ 20. A time measurement is made by below steps.
The TEC_CNTR register is split across five registers.
PLL SOURCE | VCO FREQUENCY | TEC CLOCK FREQUENCY | TEC CLOCK PERIOD (t) | ROLL-OVER TIME |
---|---|---|---|---|
PLL3 | 2500 MHz | 312.5 MHz | ~3.17 ns | ~58.6 minutes |
PLL2 | 5950 MHz | 297.5 MHz | ~3.361 ns | ~61.6 minutes |
PLL2 | 5898.24 MHz | 294.912 MHz | ~3.391 ns | ~62.1 minutes |
PLL2 | 5625 MHz | 281.25 MHz | ~3.556 ns | ~65.1 minutes |
PLL2 | 5600 MHz | 280 MHz | ~3.571 ns | ~65.4 minutes |
Figure 8-32 illustrates the states of the Time Elapsed Counter function.