Pulse-Width Modulation (PWM) Module
Freescale Semiconductor
29-2
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
Main features include the following:
•
Double-buffered period and duty cycle
•
Left- or center-aligned outputs
•
Eight independent PWM modules
•
Byte-wide registers provide programmable duty cycle and period control
•
Four programmable clock sources
NOTE
The GPIO module must be configured to enable the peripheral function of
the appropriate pins (refer to
Chapter 14, “General Purpose I/O Module”
)
prior to configuring the PWM module.
29.2
Memory Map/Register Definition
This section describes the registers and control bits in the PWM module. There are eight independent
PWM modules, each with its own control and counter registers. The memory map for the PWM is shown
below.
Table 29-1. PWM Memory Map
IPSBAR Offset
1,2
1
Addresses not assigned to a register and undefined register bits are reserved for expansion. Write accesses to these
reserved address spaces and reserved register bits have no effect.
2
A 32-bit access to any of these registers results in a bus transfer error.
Register
Width
(bits)
Access
Reset Value
Section/Page
Supervisor Read/Write Only Access
0x1B_0000
PWM Enable Register (PWME)
8
R/W
0x00
0x1B_0001
PWM Polarity Register (PWMPOL)
8
R/W
0x00
0x1B_0002
PWM Clock Select Register (PWMCLK)
8
R/W
0x00
0x1B_0003
PWM Prescale Clock Select Register (PWMPRCLK)
8
R/W
0x00
0x1B_0004
PWM Center Align Enable Register (PWMCAE)
8
R/W
0x00
0x1B_0005
PWM Control Register (PWMCTL)
8
R/W
0x00
0x1B_0008
PWM Scale A Register (PWMSCLA)
8
R/W
0x00
0x1B_0009
PWM Scale B Register (PWMSCLB)
8
R/W
0x00
0x1 n
n = 0–7
PWM Channel n Counter Register (PWMCNTn)
8
R/W
0x00
0x1 n
n = 0–7
PWM Channel n Period Register (PWMPERn)
8
R/W
0xFF
0x1 n
n = 0–7
PWM Channel n Duty Register (PWMDTYn)
8
R/W
0xFF
0x1B_0024
PWM Shutdown Register (PWMSDN)
8
R/W
0x00
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:MCF52234CVM60,
MCF52235CVM60