MC68HC08AS32 Datasheet, PDF (202/394 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

Input/Output (I/O) Ports
15.8.2 Data Direction Register F
Data direction register F determines whether each port F pin is an input
or an output. Writing a logic 1 to a DDRF bit enables the output buffer for
the corresponding port F pin; a logic 0 disables the output buffer.
Address: $000D
Bit 7
6
5
4
3
2
1
Read: 0
0
0
0
DDRF3 DDRF2 DDRF1
Write: R
R
R
R
Reset: 0
0
0
0
0
0
0
R = Reserved
Figure 15-17. Data Direction Register F (DDRF)
Bit 0
DDRF0
0
DDRF[3:0] — Data Direction Register F Bits
These read/write bits control port F data direction. Reset clears
DDRF[3:0], configuring all port F pins as inputs.
1 = Corresponding port F pin configured as output
0 = Corresponding port F pin configured as input
NOTE: Avoid glitches on port F pins by writing to the port F data register before
changing data direction register F bits from 0 to 1.
Figure 15-18 shows the port F I/O logic.
READ DDRF ($000D)
WRITE DDRF ($000D)
RESET
DDRFx
WRITE PTF ($0009)
PTFx
PTFx
READ PTF ($0009)
Figure 15-18. Port F I/O Circuit
Advance Information
202
Input/Output (I/O) Ports
MC68HC08AS32 — Rev. 3.0
MOTOROLA