MC68HC908LD64 Datasheet, PDF (312/362 Pages) Freescale Semiconductor, Inc – Microcontrollers

Input/Output (I/O) Ports
19.7.2 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.
Address: $0009
Bit 7
6
5
4
3
2
1
Read:
DDRE7 DDRE6 DDRE5 DDRE4 DDRE3 DDRE2 DDRE1
Write:
Reset: 0
0
0
0
0
0
0
Figure 19-18. Data Direction Register E (DDRE)
Bit 0
DDRE0
0
DDRE[7:0] — Data Direction Register E Bits
These read/write bits control port E data direction. Reset clears
DDRE[7:0], 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 19-19 shows the port E I/O logic.
READ DDRE ($0009)
WRITE DDRE ($0009)
RESET
WRITE PTE ($0008)
READ PTE ($0008)
DDREx
PTEx
PTEx
Figure 19-19. Port E I/O Circuit
Data Sheet
312
Input/Output (I/O) Ports
MC68HC908LD64 — Rev. 3.0
Freescale Semiconductor