MPC555
/
MPC556
MODULAR INPUT/OUTPUT SUBSYSTEM (MIOS1)
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
15-23
15.11.1.4 MDASM Status/Control Register
The status/control register contains a read-only bit reflecting the status of the MDASM
pin as well as read/write bits related to its control and configuration.
for a complete list of all the base addresses for the MDASM registers.
MDASMSCR
— MDASM Status/Control Register
0x30 605E*
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
LSB
15
PIN
WOR
FREN
0
ED-
POL
FORC
A
FORC
B
RESERVED
BSL
0
MOD
RESET:
—
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Table 15-17 MDASMSCR Bit Descriptions
Bit(s)
Name
Description
0
PIN
Pin input status. The pin input status bit reflects the status of the corresponding pin.
1
WOR
Wired-OR. In the DIS, IPWM, IPM and IC modes, the WOR bit is not used; reading this bit re-
turns the value that was previously written. In the OCB, OCAB and OPWM modes, the WOR bit
selects whether the output buffer is configured for open-drain or totem-pole operation.
0 = Output buffer is totem-pole.
1 = Output buffer is open-drain.
2
FREN
Freeze enable. This active high read/write control bit enables the MDASM to recognize the
MIOB freeze signal.
0 = The MDASM is not frozen even if the MIOB freeze line is active.
1 = The MDASM is frozen if the MIOB freeze line is active.
3
—
0
4
EDPOL
Polarity. In the DIS mode, this bit is not used; reading it returns the last value written.
In the IPWM mode, this bit is used to select the capture edge sensitivity of channels A and B.
0 = Channel A captures on a rising edge. Channel B captures on a falling edge.
1 = Channel A captures on a falling edge. Channel B captures on a rising edge.
In the IPM and IC modes, the EDPOL bit is used to select the input capture edge sensitivity of
channel A.
0 = Channel A captures on a rising edge.
1 = Channel A captures on a falling edge.
In the OCB, OCAB and OPWM modes, the EDPOL bit is used to select the voltage level on the
output pin.
0 = The output flip-flop logic level appears on the output pin: a compare on channel A sets the
output pin, a compare on channel B resets the output pin.
1 = The complement of the output flip-flop logic level appears on the output pin: a compare on
channel A resets the output pin; a compare on channel B sets the output pin.
5
FORCA
Force A. In the OCB, OCAB and OPWM modes, the FORCA bit allows the software to force the
output flip-flop to behave as if a successful comparison had occurred on channel A (except that
the FLAG line is not activated). Writing a one to FORCA sets the output flip-flop; writing a zero
to it has no effect.
In the DIS, IPWM, IPM and IC modes, the FORCA bit is not used and writing to it has no effect.
FORCA is cleared by reset and is always read as zero. Writing a one to both FORCA and
FORCB simultaneously resets the output flip-flop.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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