Motorola MC68VZ328 - Manual (Page 198)

10-28 MC68VZ328 User’s Manual
Programming Model
10.4.8 Port G Registers
Port G is comprised of the following 8-bit general-purpose I/O registers:
• Port G direction register (PGDIR)
• Port G data register (PGDATA)
• Port G pull-up enable register (PGPUEN)
• Port G select register (PGSEL)
Each signal in the PGDATA register connects to an external pin. It should be noted that pins 6 and 7 are
not connected to external pins. Port G provides a total of six pins, and each bit is individually configured.
10.4.8.1 Port G Direction Register
The Port G direction register controls the direction (input or output) of the line associated with the
PGDATA bit position. When the data bit is assigned to a dedicated I/O function by the PGSEL register, the
DIR bits are ignored. The settings for the PGDIR bit positions are shown in Table 10-36.
PGDIR Port G Direction Register 0x(FF)FFF430
10.4.8.2 Port G Data Register
The settings for the bit positions of the PGDATA register are shown in Table 10-37 on page 10-29.
BIT 7 6 5 4 3 2 1 BIT 0
DIR5 DIR4 DIR3 DIR2 DIR1 DIR0
TYPE rw rw rw rw rw rw
RESET
0 0 0 0 0 0 0 0
0x00
Table 10-36. Port G 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 = Input
1 = Output