MC68HC912B32CFU8 Freescale Semiconductor, MC68HC912B32CFU8 Datasheet - Page 139

• Manufacturer Part Number: MC68HC912B32CFU8
• Description: IC MCU 32K FLASH 8MHZ 80-QFP
• Manufacturer: Freescale Semiconductor
• Series: HC12r

Specifications of MC68HC912B32CFU8

• Core Processor: CPU12
• Core Size: 16-Bit
• Speed: 8MHz
• Connectivity: SCI, SPI
• Peripherals: POR, PWM, WDT
• Number Of I /o: 63
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: FLASH
• Eeprom Size: 768 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 80-QFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

11.4.1 PWM Period Calculation
These parameters were used to calculate the high-time values shown in
Table
11.4.2 Equipment
For this exercise, use the M68HC912B32EVB emulation board.
Freescale Semiconductor
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11-3:
Period = $1000 (Hex) = 4096 (decimal)
E clock = 8 MHz
Prescaler = 4
Frequency = (8 MHz) / (#clocks_count*prescaler) = (8 MHz) (4096*4)
= 500 Hz
If period ($4096 Clocks) => frequency = 500 Hz
HEX Count
$0D9A
$0C00
$0020
$0040
$0080
$0100
$0200
$0040
$0080
$0996
$1000
High-Time Values
Table 11-3. PWM Period Calculations
M68HC12B Family Data Sheet, Rev. 9.1
Decimal Count
1024
2048
2454
3072
3482
4096
128
256
512
32
64
Using the Output Compare 7 Feature to Generate a PWM
Duty Cycle
100.00%
12.50%
25.00%
50.00%
60.00%
75.00%
85.00%
6.25%
1.5%
3.1%
0%
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