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MPC555
/
MPC556
MODULAR INPUT/OUTPUT SUBSYSTEM (MIOS1)
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
15-17
15.10.1.4 MMCSM Status/Control Register (MMCSMSCR)
This register contains both read-only status bits and read/write control bits.
MMCSMSCRD
— MMCSM Status/Control Register (Duplicated)
0x30 6034
0x30 60B4
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
PINC
PINL
FREN EDGN EDGP
CLS
—
CP
RESET:
—
—
0
0
0
0
0
0
U
U
U
U
U
U
U
U
MMCSMSCR
— MMCSM Status/Control Register
0x30 6036
0x30 60B6
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
PINC
PINL
FREN EDGN EDGP
CLS
—
CP
RESET:
—
—
0
0
0
0
0
0
U
U
U
U
U
U
U
U
Table 15-14 MMCSMSCR Bit Descriptions
Bit(s)
Name
Description
0
PINC
Clock input pin status. This read-only status bit reflects the logic state of the clock input pin
MMCnC (MDA11 or MDA13).
1
PINL
Modulus load input pin status. This read-only status bit reflects the logic state of the modulus
load pin MMCnL (MDA12 or MDA14).
2
FREN
Freeze enable. This active high read/write control bit enables the MMCSM to recognize the
MIOB freeze signal.
3:4
EDGN,
EDGP
Modulus load falling edge/rising edge sensitivity. These active high read/write control bits set
falling-edge and rising edge sensitivity, respectively, for the MMCnL pin (MDA12 or MDA14).
00 = Disabled
01 = MMCSMCNT load on rising edges
10 = MMCSMCNT load on falling edges
11 = MMCSMCNT load on rising and falling edges
5:6
CLS
Clock select. These read/write control bits select the clock source for the modulus counter.
00 = Disabled
01 = Falling edge of MMCnC (MDA11 or MDA13) pin
10 = Rising edge of MMCnC (MDA11 or MDA13) pin
11 = MMCSM clock prescaler
7
—
—
8:15
CP
Clock prescaler. This 8-bit read/write data register stores the two’s complement of the desired
modulus value for loading into the built-in 8-bit clock prescaler. The new value is loaded into the
prescaler counter when the next counter overflow occurs or when the CLS bits are set to select
the clock prescaler as the clock source.
gives the clock divide ratio according to the
CP values
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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