3.8.1.2 Clock Options
The TPM blocks are clocked from a single TPM clock that can be selected from
OSCERCLK, MCGIRCLK, MCGPLLCLK/2, or MCGFLLCLK. The selected source is
controlled by SIM_SOPT2[TPMSRC] and SIM_SOPT2[PLLFLLSEL]control registers.
Each TPM also supports an external clock mode (TPM_SC[CMOD]=1x) in which the
counter increments after a synchronized (to the selected TPM clock source) rising edge
detect of an external clock input. The available external clock (either TPM_CLKIN0 or
TPM_CLKIN1) is selected by SIM_SOPT4[TPMxCLKSEL] control register. To
guarantee valid operation the selected external clock must be less than half the frequency
of the selected TPM clock source.
3.8.1.3 Trigger Options
Each TPM has a selectable trigger input source controlled by the
TPMx_CONF[TRGSEL] field to use for starting the counter and/or reloading the
counter. The options available are shown in the following table.
Table 3-38. TPM trigger options
TPMx_CONF[TRGSEL] Selected source
0000 External trigger pin input (EXTRG_IN)
0001 CMP0 output
0010 Reserved
0011 Reserved
0100 PIT trigger 0
0101 PIT trigger 1
0110 Reserved
0111 Reserved
1000 TPM0 overflow
1001 TPM1 overflow
1010 TPM2 overflow
1011 Reserved
1100 RTC alarm
1101 RTC seconds
1110 LPTMR trigger
1111 Reserved
Timers
KL25 Sub-Family Reference Manual, Rev. 3, September 2012
86 Freescale Semiconductor, Inc.
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