MC68HC08AS32 Datasheet, PDF (190/394 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

Input/Output (I/O) Ports
When bit DDRBx is a logic 1, reading address $0001 reads the PTBx
data latch. When bit DDRBx is a logic 0, reading address $0001 reads
the voltage level on the pin, or logic 0 if that particular bit is in use by the
ADC. The data latch can always be written, regardless of the state of its
data direction bit. Table 15-3 summarizes the operation of the port B
pins.
Table 15-3. Port B Pin Functions
DDRB
Bit
0
PTB
Bit
X
Bit in Use
by ADC
No
I/O Pin
Mode
Input, Hi-Z
Accesses
to DDRB
Read/Write
DDRB[7:0]
Accesses to PTB
Read
Pin
Write
PTB[7:0]⁽¹⁾
1
X
0
X
No
Output DDRB[7:0] PTB[7:0] PTB[7:0]
Yes
Input, Hi-Z DDRB[7:0]
0
PTB[7:0]⁽¹⁾
1
X
Yes
Input, Hi-Z DDRB[7:0] PTB[7:0] PTB[7:0]
X = Don’t Care
Hi-Z = High Impedance
1. Writing affects data register, but does not affect input.
Advance Information
190
Input/Output (I/O) Ports
MC68HC08AS32 — Rev. 3.0
MOTOROLA