NXP Semiconductors MPC5566, Reference Manual

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Enhanced Modular Input/Output Subsystem (eMIOS)
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 17-77
Figure 17-59 shows the prescaler ratio equal to three, therefore, the prescaled clock pulses every three
clock cycles and the internal counter increments every three clock cycles:
Figure 17-59. eMIOS Time Base Example — Prescale Ratio = 3, Match Value = 3
Figure 17-60 shows an example of time-base generation using the internal clock with clear on match start:
Figure 17-60. Time Base Generation Using the Internal Clock with Clear on Match Start
Prescaled clock
Internal counter
1 2 0 3
Clock
3 1 2 3 0 1 2
EMIOS_CCNTR n
(Ratio = 3)
Match value = 3
Initial time base period does
not include the match value.
the internal counter, starting another period.
When a match occurs, the first clock cycle clears
0
1 2
3 2
3 1
Prescaler clock enable
Internal counter
1
2 0
System clock
3
0 1
3 0
Match value = 3
2 0
Flag pin and register
Flag clear
Flag set event
Read note 1
Prescaled clock ratio = 3
Note 1: When a match occurs, the first clock cycle is used to clear the
internal counter. The internal counter starts counting after the
second edge of the prescaled clock.