
Pulse-Width Modulation (PWM) Module
Freescale Semiconductor
26-19
Eqn. 26-10
26.3.2.6.1
Center-Aligned Output Example
As an example of a center-aligned output, consider the following case:
Clock source = internal bus clock, where internal bus clock = 80 MHz (12.5 ns period)
PPOL
n
= 0, PWMPER
n
= 4, PWMDTY
n
= 1
PWM
n
frequency = 80 MHz / (2
×
4) = 10 MHz
PWM
n
period = 100 ns
Shown below is the generated output waveform.
Figure 26-19. PWM Center-Aligned Output Example Waveform
26.3.2.7
PWM 16-Bit Functions
The PWM timer also has the option of generating 48-bit channels or four 16-bit channels for greater PWM
resolution. This 16-bit channel option is achieved through the concatenation of two 8-bit channels.
The PWMCTL register contains four concatenation control bits, each used to concatenate a pair of PWM
channels into one 16-bit channel. Channels 0 and 1 are concatenated with the CON01 bit, channels 2 and
3 are concatenated with the CON23 bit, and so on. Change these bits only when both corresponding
channels are disabled.
, when channels 2 and 3 are concatenated, channel 2 registers become the high
order bytes of the double byte channel. When channels 0 and 1 are concatenated, channel 0 registers
become the high order bytes of the double byte channel.
When using the 16-bit concatenated mode, the clock source is determined by the low order 8-bit channel
clock select control bits (the odd numbered channel). The resulting PWM is output to the pins of the
corresponding low order 8-bit channel, as shown in
. The polarity of the resulting PWM
output is controlled by the PPOL
n
bit of the corresponding low order 8-bit channel as well.
After concatenated mode is enabled (PWMCTL[CON
nn
] bits set), enabling/disabling the corresponding
16-bit PWM channel is controlled by the low order PWME
n
bit. In this case, the high order bytes’ PWME
n
bits have no effect, and their corresponding PWM output is disabled.
In concatenated mode, writes to the 16-bit counter by using a 16-bit access or writes to the low or high
order byte of the counter resets the 16-bit counter. Reads of the 16-bit counter must be made by 16-bit
access to maintain data coherency.
Duty Cycle
1
PWMPOL PPOL
n
[
]
PWMDTY
n
PWMPER
n
-------------------------------
–
–
⎝
⎠
⎛
⎞
100%
×
=
PWMn Duty Cycle
1
1
4
---
–
⎝
⎠
⎛
⎞
100% 75%
=
×
=
DUTY CYCLE = 75%
E = 12.5ns
PERIOD = 100ns
E = 12.5ns
MCF5329 Reference Manual, Rev 3
Summary of Contents for MCF5329
Page 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...