Rainbow Electronics AT89C5122 - Manual (Page 53)

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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