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Pulse-Width Modulator (S12PWM8B8CV2)
MC9S12VRP Family Reference Manual Rev. 1.3
NXP Semiconductors
291
9.4.2
PWM Channel Timers
The main part of the PWM module are the actual timers. Each of the timer channels has a counter, a period
register and a duty register (each are 8-bit). The waveform output period is controlled by a match between
the period register and the value in the counter. The duty is controlled by a match between the duty register
and the counter value and causes the state of the output to change during the period. The starting polarity
of the output is also selectable on a per channel basis. Shown below in
for the PWM timer.
Figure 9-16. PWM Timer Channel Block Diagram
9.4.2.1
PWM Enable
Each PWM channel has an enable bit (PWMEx) to start its waveform output. When any of the PWMEx
bits are set (PWMEx = 1), the associated PWM output signal is enabled immediately. However, the actual
PWM waveform is not available on the associated PWM output until its clock source begins its next cycle
due to the synchronization of PWMEx and the clock source. An exception to this is when channels are
concatenated. Refer to
Section 9.4.2.7, “PWM 16-Bit Functions”
for more detail.
NOTE
The first PWM cycle after enabling the channel can be irregular.
Clock Source
T
R
Q
Q
PPOLx
From Port PWMP
Data Register
PWMEx
To Pin
Driver
Gate
8-bit Compare =
PWMDTYx
8-bit Compare =
PWMPERx
CAEx
T
R
Q
Q
8-Bit Counter
PWMCNTx
M
U
X
M
U
X
(Clock Edge
Sync)
Up/Down
Reset
Summary of Contents for MC9S12VRP64
Page 16: ...MC9S12VRP Family Reference Manual Rev 1 3 16 NXP Semiconductors ...
Page 46: ...Device Overview S12VRP Series MC9S12VRP Family Reference Manual Rev 1 3 46 NXP Semiconductors ...
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Page 244: ...Interrupt Module S12SINTV1 MC9S12VRP Family Reference Manual Rev 1 3 244 NXP Semiconductors ...
Page 358: ...Timer Module TIM16B2CV3 MC9S12VRP Family Reference Manual Rev 1 3 358 NXP Semiconductors ...
Page 436: ...Supply Voltage Sensor BATSV2 MC9S12VRP Family Reference Manual Rev 1 3 436 NXP Semiconductors ...
Page 528: ...NVM Electrical Parameters MC9S12VRP Family Reference Manual Rev 1 3 528 NXP Semiconductors ...
Page 530: ...Package Information MC9S12VRP Family Reference Manual Rev 1 3 530 NXP Semiconductors ...
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