mc68hc05j1avp Freescale Semiconductor, Inc, mc68hc05j1avp Datasheet - Page 64

• Manufacturer Part Number: mc68hc05j1avp
• Description: M68hc05 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Parallel Input/Output (I/O)
7.4.3 Pulldown Register A
Technical Data
64
NOTE:
Address:
All port A pins have mask-optional, programmable pulldown devices that
typically sink 100 A. Clearing the PDIA7–PDIA0 bits in pulldown
register A (PDRA) turns on the pulldown devices. See
Pulldown register A can turn on a port A pulldown device only when the
port A pin is an input. Reset clears the PDIA7–PDIA0 bits, turning on all
the port A pulldown devices.
PDIA7–PDIA0 — Port A Pulldown Inhibit Bits
Avoid a floating port A input by clearing its pulldown register bit before
changing its DDRA bit from logic 1 to logic 0.
Do not use read-modify-write instructions on pulldown register A.
Reset:
Read:
Write:
Writing logic 0s to these write-only bits turns on the port A pulldown
devices. Reading pulldown register A returns undefined data.
Freescale Semiconductor, Inc.
For More Information On This Product,
1 = Corresponding port A pin pulldown device turned off
0 = Corresponding port A pin pulldown device turned on
PDIA7
$0010
Bit 7
0
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Parallel Input/Output (I/O)
Figure 7-3. Pulldown Register A (PDRA)
= Unimplemented
PDIA6
6
0
PDIA5
5
0
PDIA4
4
0
PDIA3
3
0
MC68HC05J1A — Rev. 3.0
PDIA2
2
0
Figure
PDIA1
1
0
MOTOROLA
7-3.
PDIA0
Bit 0
0