Motorola MC68VZ328 - Manual (Page 182)

10-12 MC68VZ328 User’s Manual
Programming Model
10.4.3.1 Port C Direction Register
The Port C direction register controls the direction (input or output) of the line associated with the
PCDATA bit position. When the data bit is assigned to a dedicated I/O function by the PCSEL register, the
DIR bits are ignored. The settings for the bit positions are shown in Table 10-12.
PCDIR Port C Direction Register 0x(FF)FFF410
10.4.3.2 Port C Data Register
The settings for the PCDATA bit positions are shown in Table 10-13.
PCDATA Port C Data Register 0x(FF)FFF411
Port C is primarily multiplexed with the LCD controller’s signals. These pins can be programmed as GPIO
when the LCD controller is not used. See Section 8.2.1, “Connecting the LCD Controller to an LCD
Panel,” on page 8-3 for more detailed information.
These bits control or report the data on the pins while the associated SELx bits are high. While the DIRx
bits are high (output), the Dx bits control the pins. While the DIRx bits are low (input), the Dx bits report
the signal driving the pins. The Dx bits can be written at any time. Bits that are configured as inputs will
BIT 7 6 5 4 3 2 1 BIT 0
DIR7 DIR6 DIR5 DIR4 DIR3 DIR2 DIR1 DIR0
TYPE rw rw rw rw rw rw rw rw
RESET
0 0 0 0 0 0 0 0
0x00
Table 10-12. Port C Direction Register Description
Name Description Setting
DIRx
Bits 7–0 Direction—These bits control the direction of the pins in an 8-bit sys-
tem. They reset to 0. 0 = Input
1 = Output
BIT 7 6 5 4 3 2 1 BIT 0
D7 D6 D5 D4 D3 D2 D1 D0
TYPE rw rw rw rw rw rw rw rw
RESET
0 0 0 0 0 0 0 0
0x00*
*Actual bit value depends on external circuits connected to pin.
Table 10-13. Port C Data Register Description
Name Description Setting
Dx
Bits 7–0 Data—These bits reflect the
status of the I/O signal. 0 = Drives the output signal low when DIRx is set to 1 or the
external signal is low when DIRx is set to 0
1 = Drives the output signal high when DIRx is set to 1 or the
external signal is high when DIRx is set to 0