st10f269z1 STMicroelectronics, st10f269z1 Datasheet - Page 65

• Manufacturer Part Number: st10f269z1
• Description: St10f269 16-bit Mcu With Mac Unit, 256k Byte Flash Memory And 12k Byte Ram
• Manufacturer: STMicroelectronics

ST10F269
When an external bus mode is enabled, the
direction of the port pin and the loading of data
into the port output latch are controlled by the bus
controller hardware.
The input of the port output Buffer is disconnected
from the internal bus and is switched to the line
labeled “Alternate Data Output” via a multiplexer.
The alternate data can be the 16-bit intra-segment
address or the 8/16-bit data information. The
incoming data on PORT0 is read on the line
Figure 22 : Block Diagram of a PORT0 Pin
Write P0H.y / P0L.y
Write DP0H.y / DP0L.y
Read DP0H.y / DP0L.y
Read P0H.y / P0L.y
Port Output
Direction
Latch
Latch
MUX
Alternate
Direction
Port Data
Output
1
0
Alternate
Function
Enable
Alternate
Data
Output
1
0
1
0
“Alternate Data Input”. While an external bus
mode is enabled, the user software should not
write
unpredictable results may occur.
When the external bus modes are disabled, the
contents of the direction register last written by the
user becomes active.
The Figure 22 shows the structure of a PORT0
pin.
MUX
MUX
to
the
Clock
Latch
Input
port
12 - PARALLEL PORTS
Output
Buffer
output
latch,
y = 7...0
otherwise
P0H.y
P0L.y
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