MC68HC08AS32A Datasheet, PDF (167/296 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Input/Output (I/O) Ports
Port E
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 12-16 shows the port E I/O logic.
READ DDRE ($000C)
WRITE DDRE ($000C)
RESET
WRITE PTE ($0008)
DDREx
PTEx
PTEx
READ PTE ($0008)
Figure 12-16. Port E I/O Circuit
When bit DDREx is a logic 1, reading address $0008 reads the PTEx data latch.
When bit DDREx is a logic 0, 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. Table 12-5 summarizes the operation of the port E pins.
Table 12-5. Port E Pin Functions
Accesses
DDRE
PTE
I/O Pin
to DDRE
Bit
Bit
Mode
Read/Write
0
X
Input, Hi-Z
DDRE[7:0]
1
X
Output
DDRE[7:0]
X = Don’t Care
Hi-Z = High Impedance
1. Writing affects data register, but does not affect input.
Accesses to PTE
Read
Pin
PTE[7:0]
Write
PTE[7:0]⁽¹⁾
PTE[7:0]
MC68HC08AS32A — Rev. 1
MOTOROLA
Input/Output (I/O) Ports
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Data Sheet
167