MC908AZ32ACFUE Datasheet, PDF (256/324 Pages) Freescale Semiconductor, Inc – Microcontrollers

I/O Ports
23.7.2 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:
Read:
Write:
Reset:
$000D
Bit 7
6
5
4
3
2
1
0
DDRF6 DDRF5 DDRF4 DDRF3 DDRF2 DDRF1
R
0
0
0
0
0
0
0
R
= Reserved
Figure 23-18. Data Direction Register F (DDRF)
Bit 0
DDRF0
0
DDRF[6:0] — Data Direction Register F Bits
These read/write bits control port F data direction. Reset clears DDRF[6:0], 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 23-19 shows the port F I/O logic.
READ DDRF ($000D)
WRITE DDRF ($000D)
RESET
DDRFx
WRITE PTF ($0009)
PTFx
PTFx
READ PTF ($0009)
Figure 23-19. Port F I/O Circuit
MC68HC908AZ32A Data Sheet, Rev. 2
256
Freescale Semiconductor