Port M - Motorola DragonBall MC68328 User Manual

Parallel Ports
are configured as outputs. The actual value on the pin is reported when these bits are
read.
PULLUP - PU[7:0]
These bits enable the pullup resistors on the port. While high, the pullup resistors are en-
abled; while low, they are disabled. Port E, bit 7 pullup resistor is enabled after reset.
SELECT- SEL[7:0]
These bits select whether serial-module or port I/O signals are connected to the pins.
While high, the port I/O function is connected to the pin. While low, the serial module func-
tions are connected.

7.1.11 Port M

Port M is multiplexed with signals related to the interrupts and UART. The signals are iden-
tified below. Each bit has a selectable pullup resistor associated with it.
All 8 bits are implemented in the registers and each is connected to the outside. As with
other ports, each bit can be individually configured, as needed. Note that there is no alter-
nate signal associated with bit 7. The programmer's model for port M is shown below.
15 14 13 12
DIRECTION
DIR7 DIR6 DIR5 DIR4
Address: $FFFFF448
15 14 13 12
PU7 PU6 PU5 PU4
Address: $FFFFF44A
7-14 MC68328 DRAGONBALL PROCESSOR USER'S MANUAL
Table 7-6. Port M Bit Functions
Bit Port Function Other Function
0
1
2
3
4
5
6
7
11 10 9
DIR3 DIR2 DIR1
Figure 7-24. Port M Data/Direction Register
11 10 9
PULLUP
PU3 PU2 PU1
Figure 7-25. Port M Select Register
Bit 0 CTS
Bit 1 RTS
Bit 2 IRQ 6
Bit 3 IRQ 3
Bit 4 IRQ 2
Bit 5 IRQ 1
Bit 6 PEN IRQ
Bit 7 UART GPIO
8 7 6 5
DIR0 D7 D6 D5
8 7 6 5
PU0 SEL7 SEL6 SEL5
4 3 2 1
DATA
D4 D3 D2 D1
Reset Value: $0000
4 3 2 1
SELECT
SEL4 SEL3 SEL2 SEL1
Reset Value: $0000
MOTOROLA
0
D0
0
SEL0