mc68hc908mr24 Freescale Semiconductor, Inc, mc68hc908mr24 Datasheet - Page 212

• Manufacturer Part Number: mc68hc908mr24
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Timer Interface A (TIMA)
11.4.4 Pulse-Width Modulation (PWM)
Advance Information
212
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 (see
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
Figure 11-3
OVERFLOW
Figure 11-3. PWM Period and Pulse Width
Timer Interface A (TIMA)
shows, the output compare value in the TIMA channel
PULSE
WIDTH
11.8.1 TIMA Status and Control
PERIOD
COMPARE
OUTPUT
OVERFLOW
COMPARE
OUTPUT
MC68HC908MR24
OVERFLOW
Freescale Semiconductor
Register).
—
COMPARE
Rev. 4.1
OUTPUT