Input/Output (I/O) Ports
Technical Data
MC68HC908GP32
•
MC68HC08GP32
—
Rev. 6
232
Input/Output (I/O) Ports
MOTOROLA
16.7.2 Data Direction Register E
Data direction register E (DDRE) determines whether each port E pin is
an input or an output. Writing a logic 1 to a DDRE bit enables the output
buffer for the corresponding port E pin; a logic 0 disables the output
buffer.
DDRE1 and DDRE0 — Data Direction Register E Bits
These read/write bits control port E data direction. Reset clears
DDRE1 and DDRE0, configuring all port E pins as inputs.
1 = Corresponding port E pin configured as output
0 = Corresponding port E pin configured as input
NOTE:
Avoid glitches on port E pins by writing to the port E data register before
changing data direction register E bits from 0 to 1.
Figure 16-19
shows the port E I/O logic.
Address:
$000C
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
0
0
0
DDRE1
DDRE0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 16-18. Data Direction Register E (DDRE)
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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