mc68hc908as60 Freescale Semiconductor, Inc, mc68hc908as60 Datasheet - Page 385

• Manufacturer Part Number: mc68hc908as60
• Description: Mc68hc908as60 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

22.4.4 Pulse-Width Modulation (PWM)
MC68HC908AS60 — Rev. 1.0
By using the toggle-on-overflow feature with an output compare channel,
the TIMA can generate a PWM signal. The value in the TIMA counter
modulo registers determines the period of the PWM signal. The channel
pin toggles when the counter reaches the value in the TIMA counter
modulo registers. The time between overflows is the period of the PWM
signal.
As
registers determines the pulse width of the PWM signal. The time
between overflow and output compare is the pulse width. Program the
TIMA to clear the channel pin on output compare if the state of the PWM
pulse is logic 1. Program the TIMA to set the pin if the state of the PWM
pulse is logic 0.
The value in the TIMA counter modulo registers and the selected
prescaler output determines the frequency of the PWM output. The
frequency of an 8-bit PWM signal is variable in 256 increments. Writing
$00FF (255) to the TIMA counter modulo registers produces a PWM
period of 256 times the internal bus clock period if the prescaler select
value is $000
The value in the TIMA channel registers determines the pulse width of
the PWM output. The pulse width of an 8-bit PWM signal is variable in
256 increments. Writing $0080 (128) to the TIMA channel registers
produces a duty cycle of 128/256 or 50 percent.
PTEx/TCHx
Freescale Semiconductor, Inc.
Figure 22-3
For More Information On This Product,
OVERFLOW
Timer Interface Module A (TIMA-6)
Go to: www.freescale.com
Figure 22-3. PWM Period and Pulse Width
22.9.1 TIMA Status and Control
shows, the output compare value in the TIMA channel
PULSE
WIDTH
PERIOD
COMPARE
OUTPUT
OVERFLOW
Timer Interface Module A (TIMA-6)
COMPARE
OUTPUT
Register.
OVERFLOW
Functional Description
Technical Data
COMPARE
OUTPUT