Freescale Semiconductor MC68HC08KH12 User Manual
Page 197
MC68HC(7)08KH12
—
Rev. 1.1
Advance Information
Freescale Semiconductor
197
DDRE[4:0] — Data Direction Register E Bits
These read/write bits control port E data direction. Reset clears
DDRE[4:0], 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 12-15. Port E I/O Circuit
When bit DDREx is a logic one, reading address $0008 reads the PTEx
data latch. When bit DDREx is a logic zero, reading address $0008
reads the voltage level on the pin. The data latch can always be written,
regardless of the state of its data direction bit.
summarizes
the operation of the port E pins.
Address:
$000A
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
0
0
DDRE4
DDRE3
DDRE2
DDRE1
DDRE0
Write:
Reset:
0
0
0
0
0
0
0
0
= Unimplemented
Figure 12-14. Data Direction Register E (DDRE)
READ DDRE ($000A)
WRITE DDRE ($000A)
RESET
WRITE PTE ($0008)
READ PTE ($0008)
PTEx
DDREx
PTEx
INT
ERNAL DATA BUS