Datasheet

Input/Output Ports (I/O)
Port E
MC68HC908GR8 — Rev 4.0 Technical Data
MOTOROLA Input/Output Ports (I/O) 227
Figure 16-19. 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 16-6 summarizes
the operation of the port E pins.
READ DDRE ($000C)
WRITE DDRE ($000C)
RESET
WRITE PTE ($0008)
READ PTE ($0008)
PTEx
DDREx
PTEx
INTERNAL DATA BUS
Table 16-6. Port E Pin Functions
DDRE Bit PTE Bit I/O Pin Mode
Accesses to DDRE Accesses to PTE
Read/Write Read Write
0
X
(1)
Input, Hi-Z
(2)
DDRE1–DDRE0 Pin
PTE1–PTE0
(3)
1 X Output DDRE1–DDRE0] PTE1–PTE0 PTE1–PTE0
Notes:
1. X = Don’t care
2. Hi-Z = High impedance
3. Writing affects data register, but does not affect input.
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
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