MC68HC08AS32 Datasheet, PDF (196/394 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

Input/Output (I/O) Ports
Figure 15-12 shows the port D I/O logic.
READ DDRD ($0007)
WRITE DDRD ($0007)
RESET
WRITE PTD ($0003)
DDRDx
PTDx
PTDx
READ PTD ($0003)
Figure 15-12. Port D I/O Circuit
When bit DDRDx is a logic 1, reading address $0003 reads the PTDx
data latch. When bit DDRDx is a logic 0, reading address $0003 reads
the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit. Table 15-5 summarizes
the operation of the port D pins.
Table 15-5. Port D Pin Functions
DDRD PTD Bit in Use
Bit Bit by ADC
I/O Pin
Mode
Accesses
to DDRD
Read/Write
0
X
No
Input, Hi-Z DDRD[6:0]
1
X
No
Output DDRD[6:0]
0
X
Yes
Input, Hi-Z DDRD[6:0]
1
X
Yes
Input, Hi-Z DDRD[6:0]
X = Don’t Care
Hi-Z = High Impedance
1. Writing affects data register, but does not affect input.
Accesses to PTD
Read
Pin
PTD[6:0]
0
PTD[6:0]
Write
PTD[6:0]⁽¹⁾
PTD[6:0]
PTD[6:0]⁽¹⁾
PTD[6:0]
Advance Information
196
Input/Output (I/O) Ports
MC68HC08AS32 — Rev. 3.0
MOTOROLA