mc908jl16 Freescale Semiconductor, Inc, mc908jl16 Datasheet - Page 146

• Manufacturer Part Number: mc908jl16
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Input/Output (I/O) Ports
10.4.2 Data Direction Register D (DDRD)
Data direction register D determines whether each port D pin is an input or an output. Writing a logic 1 to
a DDRD bit enables the output buffer for the corresponding port D pin; a logic 0 disables the output buffer.
DDRD[7:0] — Data Direction Register D Bits
When DDRDx is a logic 1, reading address $0003 reads the PTDx data latch. When 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.
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These read/write bits control port D data direction. Reset clears DDRD[7:0], configuring all port D pins
as inputs.
1 = Corresponding port D pin configured as output
0 = Corresponding port D pin configured as input
Address: $0007
Avoid glitches on port D pins by writing to the port D data register before
changing data direction register D bits from 0 to 1.
port D I/O logic.
Reset:
Read:
Write:
READ DDRD ($0007)
WRITE DDRD ($0007)
WRITE PTD ($0003)
READ PTD ($0003)
DDRD7
Bit 7
0
Figure 10-11. Data Direction Register D (DDRD)
DDRD6
6
0
RESET
Figure 10-12. Port D I/O Circuit
MC68HC908JL16 Data Sheet, Rev. 1.1
DDRD5
5
0
NOTE
DDRD4
DDRDX
PTDX
4
0
DDRD3
3
0
Figure 10-12
DDRD2
2
0
PTDPU[6:7]
TO ADC, TIM1, SCI
DDRD1
1
0
shows the
Freescale Semiconductor
DDRD0
Bit 0
PTDX
0