Freescale Semiconductor, Inc.
Pulse Width Modulator
PSBCK
PSBCK IS BIT 0 OF PWCTL REGISTER.
INTERNAL SIGNAL LIMBDM IS ONE IF THE MCU IS IN BACKGROUND DEBUG MODE.
LIMBDM
CLOCK A
CLOCK TO PWM
CHANNEL 0
ECLK
X
0:0:0
0:0:0
UM
= 0
8-BIT DOWN COUNTER
÷ 2
÷ 2
÷ 2
÷ 2
÷ 2
÷ 2
÷ 2
0:0:1
0:1:0
0:0:1
0:1:0
0:1:1
1:0:0
1:0:1
1:1:0
1:1:1
*
PWSCNT0
PCLK0
S
C
CLOCK TO PWM
CHANNEL 1
C
X
8-BIT SCALE REGISTER
PWSCAL0
UM
0:1:1
1:0:0
1:0:1
1:1:0
1:1:1
÷ 2
PCLK1
CLOCK B
CLOCK TO PWM
CHANNEL 2
= 0
8-BIT DOWN COUNTER
PWSCNT1
PCLK2
CLOCK TO PWM
CHANNEL 3
BITS:
BITS:
REGISTER:
PWPRES
8-BIT SCALE REGISTER
PWSCAL1
PCKA2,
PCKA1,
PCKA0
PCKB2,
PCKB1,
PCKB0
÷ 2
PCLK3
*CLOCK S0 = (CLOCK A)/2, (CLOCK A)/4, (CLOCK A)/6,... (CLOCK A)/512
**CLOCK S1 = (CLOCK B)/2, (CLOCK B)/4, (CLOCK B)/6,... (CLOCK B)/512
Figure 12-3. PWM Clock Sources
Technical Data
MC68HC912DG128 — Rev 3.0
Pulse Width Modulator
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