12 - PARALLEL PORTS ST10F269
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Figure 31 : Block Diagram of a Port 4 Pin
Direction
Latch
Write DP4.y
Read DP4.y
Port Output
Latch
Write P4.y
Read P4.y
Internal Bus
MUX
0
1
MUX
0
1
Alternate
Data
Output
MUX
0
1
“1”
Input
Latch
Clock
P4.y
Output
Buffer
y = 7...0
Alternate
Function
Enable
