mc9s12hz256v2 Freescale Semiconductor, Inc, mc9s12hz256v2 Datasheet - Page 283

• Manufacturer Part Number: mc9s12hz256v2
• Description: Hcs12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

9.4.2
The PWM duty cycle for the motor controller channel x can be determined by dividing the decimal
representation of bits D[10:0] in MCDCx by the decimal representation of the bits P[10:0] in MCPER and
multiplying the result by 100% as shown in the equation below:
Whenever D[10:0] >= P[10:0], a constant low level (RECIRC = 0) or high level (RECIRC = 1) will be
output.
9.4.3
Figure 9-22
The peripheral bus clock is the source for the motor controller counter prescaler. The motor controller
counter clock rate, f
the MCPRE[1:0] bits in motor controller control register 0 (MCCTL0). The motor controller channel
frequency of operation can be calculated using the following formula if DITH = 0:
Freescale Semiconductor
MPPRE0, MPPRE1
PWM Duty Cycle
Motor Controller Counter Clock Source
shows how the PWM motor controller timer counter clock source is selected.
Prescaler Select
Motor Controller
x = PWM Channel Number = 0, 1, 2, 3 ... 8. This equation is only valid if
DUTY <= MCPER and MCPER is not equal to 0.
Counter Clock
TC
Effective PWM Channel X % Duty Cycle
, is set by selecting the appropriate prescaler value. The prescaler is selected with
Motor Channel Frequency (Hz)
Timer
Figure 9-22. Motor Controller Counter Clock Selection
Clock f
Peripheral
Motor Controller Timer
Bus
Counter Prescaler
BUS
CLK
MC9S12HZ256 Data Sheet, Rev. 2.05
1/2
1/4
1/8
1
Generator
Clock
Motor Controller Timer
Counter Clock f
NOTE
=
TC
------------------------------ -
MCPER M
f
Clocks and
Reset
Generator
Module
=
TC
--------------------- 100%
MCPER
DUTY
11-Bit Motor Controller
Chapter 9 Motor Controller (MC10B8CV1)
Timer Counter
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