I/o port definition, Ports vs packages, Port 0 – Rainbow Electronics AT89C5122 User Manual
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AT8xC5122/23
4202E–SCR–06/06
I/O Port Definition
Ports vs Packages
Table 30. I/O Number vs Packages
Port 0
Port 0 has the following functions:
–
Default function: Port 0 is an 8-bit I/O port.
–
Alternate function: Port 0 is also the multiplexed low-order address and data
bus during accesses to external Program and Data Memory. In this
application, it uses strong internal pull-ups when emitting 1’s and it can drive
CMOS inputs without external pull-ups.
Port 0 has the following configurations:
–
Default configuration: open drain bi-directional I/O port. Port 0 pins that have
1’s written to them float, and in this state they can be used as high-
impedance inputs.
–
Configuration 2: Low speed output, “KB_OUT”
–
Configuration 3: Push-pull output
P0
P1
P2
P3
P4
P5
Total
VQFP64
QFN64
8
8
8
8
6
8
46
VQFP32
QFN32
-
8
-
8
-
1
17
PLCC28
-
6
-
6
-
1
13