Parallel Ports; I/O Ports Module; Port Operation; Basic Port - Motorola DragonBall MC68328 User Manual

SECTION 7

PARALLEL PORTS

7.1 I/O PORTS MODULE

The MC68328 processor provides 10 multipurpose, configurable parallel ports. This section
describes the operation of the ports and offers suggestions on how to best use them. Each
port is described and, where needed, individual pins are detailed.

7.1.1 Port Operation

There are three types of ports on the MC68328 processor. This section describes the func-
tionality of each port.
7.1.1.1 BASIC PORT. Ports A, B, C, E, F, G, J and K are basic ports. Figure 7-1 illustrates
their operation.
Data from
module
Output Enable
from module
Basic ports multiplex two functions onto one pin. One function is the I/O and the other is the
internal module connected to this pin. Figure 7-1 refers to signals to and from a module. For
example, for port K, bit 0, the "Data from module" signal is connected to the master SPI mod-
ule TXD signal. Because this bit is output-only, the "Output Enable from module" signal is
always asserted (enabling the output) and the "Data to module" signal in Figure 7-1 is not
used. Another example is port K, bit 1, where this signal's module function is the master SPI
RXD signal, which is input-only. In this case, the "Output Enable from module" input is
MOTOROLA
Data to
module
DATA
MPU bus
DIRECTION
SELECT
Figure 7-1. Basic Port
MC68328 DRAGONBALL PROCESSOR USER'S MANUAL
PAD BUFFER
0
PAD
1
SEL
0
1
SEL
7-1