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Chapter 20 Pulse Width Modulator with Fault Protection (PMF15B6C) Module
MC9S12XF - Family Reference Manual, Rev.1.19
922
Freescale Semiconductor
20.3.2.21 PMF Frequency Control A Register (PMFFQCA)
Read and write anytime.
Address: $0021
76543210
R
LDFQA
HALFA
PRSCA
PWMRFA
W
Reset
0
00000
Figure 20-27. PMF Frequency Control A Register (PMFFQCA)
Table 20-25. PMFFQCA Field Descriptions
Field
Description
7–4
LDFQA
Load Frequency A — This eld selects the PWM load frequency according to
Table 20-26. See
Note: The LDFQA eld takes effect when the current load cycle is complete, regardless of the state of the load
okay bit, LDOKA. Reading the LDFQA eld reads the buffered value and not necessarily the value
currently in effect.
3
HALFA
Half Cycle Reload A — This bit enables half-cycle reloads in center-aligned PWM mode. This bit has no effect
on edge-aligned PWMs.
0 Half-cycle reloads disabled
1 Half-cycle reloads enabled
2–1
PRSCA
Prescaler A — This buffered eld selects the PWM clock frequency illustrated in
Table 20-27. Note: Reading the PRSCA eld reads the buffered value and not necessarily the value currently in effect. The
PRSCA eld takes effect at the beginning of the next PWM cycle and only when the load okay bit, LDOKA,
is set.
0
PWMRFA
PWM Reload Flag A — This ag is set at the beginning of every reload cycle regardless of the state of the
LDOKA bit. Clear PWMRFA by reading PMFFQCA with PWMRFA set and then writing a logic one to the
PWMRFA bit. If another reload occurs before the clearing sequence is complete, writing logic one to PWMRFA
has no effect.
0 No new reload cycle since last PWMRFA clearing
1 New reload cycle since last PWMRFA clearing
Note: Clearing PWMRFA satises pending PWMRFA CPU interrupt requests.
Table 20-26. PWM Reload Frequency A
LDFQA
PWM Reload Frequency
LDFQ[3:0]
PWM Reload Frequency
0000
Every PWM opportunity
1000
Every 9 PWM opportunities
0001
Every 2 PWM opportunities
1001
Every 10 PWM opportunities
0010
Every 3 PWM opportunities
1010
Every 11 PWM opportunities
0011
Every 4 PWM opportunities
1011
Every 12 PWM opportunities
0100
Every 5 PWM opportunities
1100
Every 13 PWM opportunities
0101
Every 6 PWM opportunities
1101
Every 14 PWM opportunities
0110
Every 7 PWM opportunities
1110
Every 15 PWM opportunities
0111
Every 8 PWM opportunities
1111
Every 16 PWM opportunities