MC68HC08JB1 Datasheet, PDF (175/216 Pages) Motorola, Inc – Microcontrollers

11.6.2 Data Direction Register E
Data direction register E 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
Bit 0
Read: 0
0
0
0
0
DDRE4 DDRE3
DDRE1
Write:
Reset: 0
0
0
0
0
0
0
0
= Unimplemented
Figure 11-12. Data Direction Register E (DDRE)
DDRE4, DDRE3, DDRE1 — Data Direction Register E Bits
These read/write bits control port E data direction. Reset clears
DDRE4, DDRE3, and DDRE1, 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 11-13 shows the port E I/O circuit logic.
READ DDRE ($000C)
WRITE DDRE ($000C)
RESET
WRITE PTE ($0008)
DDREx
PTEx
PTEx
READ PTE ($0008)
Figure 11-13. Port E I/O Circuit
MC68HC08JB1 — Rev. 2.1
Freescale Semiconductor
Technical Data
175