mc68331cpv20b1 Freescale Semiconductor, Inc, mc68331cpv20b1 Datasheet - Page 219

• Manufacturer Part Number: mc68331cpv20b1
• Description: Mc68331 32 Bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

FPWMA — Force PWMA Value
FPWMB — Force PWMB Value
PPROUT — PWM Clock Output Enable
PPR[2:0] — PWM Prescaler/PCLK Select
SFA — PWMA Slow/Fast Select
SFB — PWMB Slow/Fast Select
F1A — Force Logic Level One on PWMA
MC68331
USER’S MANUAL
[2:0]
PPR
This field selects one of seven prescaler taps or PCLK to be PWMCNT input.
The following table shows a range of PWM output frequencies using a 16.78-MHz sys-
tem clock and 20.97 system clock.
000
001
010
011
100
101
110
111
0 = Normal PWMA operation.
1 = The value of F1A is driven out on the PWMA pin, regardless of the state of
0 = Normal PWMB operation.
1 = The value of F1B is driven out on the PWMB pin.
0 = Normal PWM operation on PWMA.
1 = TCNT clock driven out PWMA pin.
0 = PWMA period is 256 PWMCNT increments long.
1 = PWMA period is 32768 PWMCNT increments long.
0 = PWMB period is 256 PWMCNT increments long.
1 = PWMB period is 32768 PWMCNT increments long.
0 = Force logic level zero output on PWMA pin.
1 = Force logic level one output on PWMA pin.
PPROUT.
Div 16 = 1.05 MHz
Div 128 = 131 kHz
Div 2 = 8.39 MHz
Div 4 = 4.19 MHz
Div 8 = 2.10 MHz
Div 32 = 524 kHz
Div 64 = 262 kHz
16.78 MHz
PCLK
Prescaler Tap
Freescale Semiconductor, Inc.
For More Information On This Product,
Div 16 = 1.31 MHz
Div 128 = 164 kHz
Div 2 = 10.5 MHz
Div 4 = 5.25 MHz
Div 8 = 2.62 MHz
Div 32 = 655 kHz
Div 64 = 328 kHz
20.97 MHz
PPR[2:0]
PCLK
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000
001
010
011
100
101
110
111
REGISTER SUMMARY
Divide-by Factor
System Clock
16.78 MHz
PCLK/256
32.8 kHz
16.4 kHz
8.19 kHz
4.09 kHz
2.05 kHz
1.02 kHz
512 Hz
PCLK
128
16
32
64
2
4
8
SFA/B = 0
20.97 MHz
PCLK/256
20.5 kHz
10.2 kHz
5.15 kHz
2.56 kHz
1.28 kHz
641 Hz
41 kHz
PCLK/32768
16.78 MHz
64.0 Hz
32.0 Hz
16.0 Hz
256 Hz
128 Hz
8.0 Hz
4.0 Hz
SFA/B = 1
PCLK/32768
20.97 MHz
80.0 Hz
40.0 Hz
20.0 Hz
10.0 Hz
320 Hz
160 Hz
5.0 Hz
D-11
D