MC908MR16CFUE Datasheet, PDF (121/282 Pages) Freescale Semiconductor, Inc – On-chip programming firmware for use with host personal computer, Clock generator module (CGM)

Timebase
For edge-aligned mode, a 12-bit up-only counter is used to create the PWM period. Therefore, the PWM
resolution in edge-aligned mode is one clock (highest resolution is125 ns @ f_OP = 8 MHz) as shown in
Figure 12-5. Again, the timer modulus register is used to determine the maximum count. The PWM period
will equal:
(timer modulus) x (PWM clock period)
Center-aligned operation versus edge-aligned operation is determined by the option EDGE. See 5.2
Functional Description.
UP-ONLY COUNTER
MODULUS = 4
PWM = 0
PWM = 1
PWM = 2
PERIOD = 4 X (PWM
CLOCK PERIOD)
PWM = 3
PWM = 4
Figure 12-5. Edge-Aligned PWM (Positive Polarity)
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor
121