MC68HC908MR8CP Freescale Semiconductor, MC68HC908MR8CP Datasheet - Page 208

• Manufacturer Part Number: MC68HC908MR8CP
• Description: IC MCU 8K FLASH 8MHZ PWM 28-DIP
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC68HC908MR8CP

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: SCI
• Peripherals: LVD, POR, PWM
• Number Of I /o: 12
• Program Memory Size: 8KB (8K x 8)
• Program Memory Type: FLASH
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 4x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

Timer Interface A (TIMA)
11.4.4.1 Unbuffered PWM Signal Generation
Technical Data
208
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.
Any output compare channel can generate unbuffered PWM pulses as
described in
unbuffered because changing the pulse width requires writing the new
pulse width value over the value currently in the TIMA channel registers.
An unsynchronized write to the TIMA channel registers to change a
pulse width value could cause incorrect operation for up to two PWM
periods. For example, writing a new value before the counter reaches
the old value but after the counter reaches the new value prevents any
compare during that PWM period. Also, using a TIMA overflow interrupt
routine to write a new, smaller pulse width value may cause the compare
to be missed. The TIMA may pass the new value before it is written to
the TIMA channel registers.
PTBx/TCHx
OVERFLOW
11.4.4 Pulse-Width Modulation
Figure 11-3. PWM Period and Pulse Width
Timer Interface A (TIMA)
PULSE
WIDTH
11.10.1 TIMA Status and Control
PERIOD
COMPARE
OUTPUT
OVERFLOW
COMPARE
OUTPUT
(PWM). The pulses are
MC68HC908MR8 — Rev 4.1
OVERFLOW
Freescale Semiconductor
Register.
COMPARE
OUTPUT