mc68hc705j1avs Freescale Semiconductor, Inc, mc68hc705j1avs Datasheet - Page 93

• Manufacturer Part Number: mc68hc705j1avs
• Description: M68hc05 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

6.4.2 Data Direction Register B
MC68HC705J1A — Rev. 4.0
NOTE:
Address:
Data direction register B (DDRB) determines whether each port B pin is
an input or an output.
DDRB[5:0] — 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 6-8
Reset:
Read:
Write:
These read/write bits control port B data direction. Reset clears
DDRB[5:0], configuring all port B pins as inputs.
Freescale Semiconductor, Inc.
For More Information On This Product,
1 = Corresponding port B pin configured as output
0 = Corresponding port B pin configured as input
READ DDRB
WRITE DDRB
WRITE PORTB
READ PORTB
WRITE PDRB
$0005
Bit 7
0
0
Parallel Input/Output (I/O) Ports
Figure 6-7. Data Direction Register B (DDRB)
shows the I/O logic of port B.
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= Unimplemented
RESET
6
0
0
Figure 6-8. Port B I/O Circuitry
DDRB5
5
0
DDRBx
PDRBx
PBx
DDRB4
4
0
DDRB3
3
0
SWPDI
Parallel Input/Output (I/O) Ports
DDRB2
2
0
DDRB1
100- A
PULLDOWN
1
0
Technical Data
PBx
DDRB0
Bit 0
Port B
0