MC9S12Q128_10 Datasheet, PDF (353/644 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Chapter 12 Pulse-Width Modulator (PWM8B4CRev 01.24) Block Description
12.3.2.2 PWM Polarity Register (PWMPOL)
The starting polarity of each PWM channel waveform is determined by the associated PPOLx bit in the
PWMPOL register. If the polarity bit is 1, the PWM channel output is high at the beginning of the cycle
and then goes low when the duty count is reached. Conversely, if the polarity bit is 0 the output starts low
and then goes high when the duty count is reached.
Module Base + 0x0001
7
R
0
W
Reset
0
Read: anytime
6
5
4
3
2
0
PPOL3
PPOL2
0
0
0
0
0
= Unimplemented or Reserved
Figure 12-4. PWM Polarity Register (PWMPOL)
1
PPOL1
0
Write: anytime
NOTE
PPOLx register bits can be written anytime. If the polarity is changed while
a PWM signal is being generated, a truncated or stretched pulse can occur
during the transition
Table 12-2. PWMPOL Field Descriptions
0
PPOL0
0
Field
3
PPOL3
2
PPOL2
1
PPOL1
0
PPOL0
Description
Pulse Width Channel 3 Polarity
0 PWM channel 3 output is low at the beginning of the period, then goes high when the duty count is reached.
1 PWM channel 3 output is high at the beginning of the period, then goes low when the duty count is reached.
Pulse Width Channel 2 Polarity
0 PWM channel 2 output is low at the beginning of the period, then goes high when the duty count is reached.
1 PWM channel 2 output is high at the beginning of the period, then goes low when the duty count is reached.
Pulse Width Channel 1 Polarity
0 PWM channel 1 output is low at the beginning of the period, then goes high when the duty count is reached.
1 PWM channel 1 output is high at the beginning of the period, then goes low when the duty count is reached.
Pulse Width Channel 0 Polarity
0 PWM channel 0 output is low at the beginning of the period, then goes high when the duty count is reached
1 PWM channel 0 output is high at the beginning of the period, then goes low when the duty count is reached.
Freescale Semiconductor
MC9S12Q128
353
Rev 1.10