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10.4.11
Port M Registers
Port M is composed of the following four general-purpose I/O registers:
•
Port M direction register (PMDIR)
•
Port M data register (PMDATA)
•
Port M pull-up enable register (PMPUEN)
•
Port M select register (PMSEL)
Each signal in the PMDATA register connects to an external pin. It should be noted that pins 6 and 7 are
not connected to external pins.
10.4.11.1
Port M Direction Register
The direction register controls the direction (input or output) of the line associated with the PMDATA bit
position. When the data bit is assigned to a dedicated I/O function by the PMSEL register, the DIR bits are
ignored. The settings for the PMDIR register bit positions are shown in Table 10-51.
PMDIR
BIT 7
TYPE
0
RESET
Name
Reserved
Reserved
Bits 7–6
DIRx
Direction—These bits control the direction of
Bits 5–0
the pins in an 8-bit system. They reset to 0.
Port M Direction Register
6
5
DIR5
rw
0
0
Table 10-51. Port M Direction Register Description
Description
I/O Ports
4
3
2
DIR4
DIR3
DIR2
rw
rw
rw
0
0
0
0x00
These bits are reserved and should be set to
0.
0 = The pins are inputs.
1 = The pins are outputs.
Programming Model
0x(FF)FFF448
1
BIT 0
DIR1
DIR0
rw
rw
0
0
Setting
10-37
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