MC908AS60ACFN Freescale Semiconductor, MC908AS60ACFN Datasheet - Page 312

• Manufacturer Part Number: MC908AS60ACFN
• Description: IC MCU 60K FLASH 8.4MHZ 52PLCC
• Manufacturer: Freescale Semiconductor
• Series: HC08r

Specifications of MC908AS60ACFN

• Core Processor: HC08
• Core Size: 8-Bit
• Speed: 8.4MHz
• Connectivity: CAN, SCI, SPI
• Peripherals: LVD, POR, PWM
• Number Of I /o: 42
• Program Memory Size: 60KB (60K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 15x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 52-PLCC
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Timer Interface Module A (TIMA)
PTF2 pin. Writing to the TIMA channel 5 registers enables the TIMA channel 5 registers to synchronously
control the output after the TIMA overflows. At each subsequent overflow, the TIMA channel registers (4
or 5) that control the output are the ones written to last. TASC4 controls and monitors the buffered output
compare function and TIMA channel 5 status and control register (TASC5) is unused. While the MS4B bit
is set, the channel 5 pin, PTF3, is available as a general-purpose I/O pin.
25.3.4 Pulse Width Modulation (PWM)
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
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 polarity of the PWM pulse is 1. Program the TIMA to set
the pin if the polarity of the PWM pulse is 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%.
312
Figure 25-3
PTEx/TCHx
In buffered output compare operation, do not write new output compare
values to the currently active channel registers. User software should track
the currently active channel to prevent writing a new value to the active
channel. Writing to the active channel registers is the same as generating
unbuffered output compares.
shows, the output compare value in the TIMA channel registers determines the pulse width
MC68HC908AZ60A • MC68HC908AS60A • MC68HC908AS60E Data Sheet, Rev. 6
OVERFLOW
Figure 25-3. PWM Period and Pulse Width
PULSE
WIDTH
PERIOD
COMPARE
OUTPUT
OVERFLOW
NOTE
25.8.1 TIMA Status and Control
COMPARE
OUTPUT
OVERFLOW
Freescale Semiconductor
COMPARE
OUTPUT
Register).