mc68hc908bd48 Freescale Semiconductor, Inc, mc68hc908bd48 Datasheet - Page 237

• Manufacturer Part Number: mc68hc908bd48
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

17.4.2 Data Direction Register B
MC68HC908BD48
Freescale Semiconductor
NOTE:
—
Rev. 2.1
Address:
Data direction register B (DDRB) determines whether each port B pin is
an input or an output. Writing a logic 1 to a DDRB bit enables the output
buffer for the corresponding port B pin; a logic 0 disables the output
buffer.
DDRB7–DDRB0 — Data Direction Register B Bits
Avoid glitches on port B pins by writing to the port B data register before
changing data direction register B bits from 0 to 1.
Figure 17-7
Reset:
Read:
Write:
These read/write bits control port B data direction. Reset clears
DDRB7–DDRB0, configuring all port B pins as inputs.
1 = Corresponding port B pin configured as output
0 = Corresponding port B pin configured as input
DDRB7
READ DDRB ($0005)
WRITE DDRB ($0005)
WRITE PTB ($0001)
READ PTB ($0001)
$0005
Bit 7
0
Figure 17-6. Data Direction Register B (DDRB)
shows the port B I/O logic.
Input/Output (I/O) Ports
DDRB6
6
0
Figure 17-7. Port B I/O Circuit
RESET
DDRB5
5
0
DDRB4
DDRBx
PTBx
4
0
DDRB3
3
0
DDRB2
2
0
Input/Output (I/O) Ports
DDRB1
1
0
Data Sheet
DDRB0
Bit 0
PTBx
0
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