MC68HC05E0 Datasheet, PDF (57/96 Pages) Motorola, Inc – High-density complementary metal oxide semiconductor (HCMOS) microcontroller unit

Table 6-1 Port D Alternate Functions
As bidirectional I/O
PD0
PD1
PD2
PD3
PD4
PD5
PD6
PD7
Alternate function
P02 — Bus frequency clock signal
R/W — Read/write signal (readwhen high, write when low)
CS2 — Chip select signal (active low) for external RAM
CS3 — Chip select signal (active low) for external I/O
LIR — Load instruction register (active low)
A13 — Address line
A14 — Address line
A15 — Address line
Pins PD5, PD6 and PD7 have internal pull-up resistors connected to VDD.
Configuration of Port D is done via the Port D Mode Register ($0012).
6
Port D mode register
Address bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
State
on reset
$0012 EA15 EA14 EA13 DM4 DM3 DM2 DM1 DM0 0000 0001
If a bit is set in the mode register, the corresponding port bit is used only as an output irrespective
of the value in the data direction register (see Table 6-2).
Figure 6-3 shows the internal structure of Port D.
Table 6-2 Port D Mode Table
Bit
DM0
DM1
DM2
DM3
DM4
EA15
EA14
EA13
Value
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Function
port function (bidirectional)
P02 signal as output signal
port function (bidirectional)
RIW signal as output signal
port function (bidirectional)
CS2 (external RAM) signal as output signal
port function (bidirectional)
CS3 (external I/O) signal as output signal
port function (bidirectional)
LIR signal as output signal
port function (bidirectional)
A15 signal as output signal
port function (bidirectional)
A14 signal as output signal
port function (bidirectional)
A 13 signal as output signal
MC68HC05E0
PARALLEL INPUT/OUTPUT PORTS
MOTOROLA
6-5