Motorola MC68VZ328 10.4.11 Port M Registers

Programming Model
I/O Ports 10-37
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 (PMP U EN)
• 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 Table10-51.
PMDIR Port M Direction Register 0x(FF)FFF448
BIT 7654321BIT 0
DIR5 DIR4 DIR3 DIR2 DIR1 DIR0
TYPE rw rw rw rw rw rw
RESET 00000000
0x00
Table 10-51. Port M Direction Register Description
Name Description Setting
Reserved
Bits 7–6 Reserved These bits are reserved and should be set to 0.
DIRx
Bits 5–0 Direction—These bits control the direction of the pins in an 8-bit system. They reset to 0. 0 = The pins are inputs. 1 = The pins are outputs.