W78E54
PIN DESCRIPTION
The W78E54 has two operating modes, normal and flash. In normal mode, the W78E54 corresponds
to the W78C54. In flash mode, the user (the maker of the flash EEPROM writer) can access the flash
EEPROM.
P0.7-P0.0 Port 0, Bits 7-0
MODE
DESCRIPTION
Normal
Port 0, Bits 0 through 7. Port 0 is a bidirectional I/O port. This port also provides a
multiplexed low order address/data bus during accesses to external memory.
Flash
This port provides the data bus during access to the flash EEPROM.
P1.7
-
P1.0 Port 1, Bits 7
-
0
MODE
DESCRIPTION
Normal
Port 1, Bits 0 through 7. Port 1 is a bidirectional I/O port with internal pull-ups. Pins
P1.0 and P1.1 also serve as T2 (Timer 2 external input) and T2EX (Timer 2
capture/reload trigger), respectively.
Flash
This port provides the low-order address bus during access to the flash EEPROM.
P2.7
-
P2.0 Port 2, Bits 7
-
0
MODE
DESCRIPTION
Normal
Port 2, Bits 0 through 7. Port 2 is a bidirectional I/O port with internal pull-ups. This port
also provides the upper address bits for accesses to external memory..
Flash
This port provides the high-order address bus during access to the flash EEPROM.
P3.7
-
P3.0 Port 3, Bits 7
-
0
MODE
DESCRIPTION
Normal
Port 3, Bits 0 through 7. Port 3 is a bidirectional I/O port with internal pull-ups. All bits
have alternate functions.
Flash
P3.3- P3.0 and P3.7- P3.6 are the flash mode configuration pins, Input.
P3.3- P3.0 and P3.7- P3.6 are configured to select or execute the flash operations. For
details, see Flash Operations.
P4.3
-
P4.0 Port 4, Bits 3
-
0 (available on 44-pin PLCC/QFP package)
MODE
DESCRIPTION
Normal
Another bit-addressable bidirectional I/O port P4. P4.3 and P4.2 are alternative
function pins. It can be used as general I/O pins or external interrupt input sources
(INT2 /INT3 ).
Publication Release Date: November 1997
- 3 -
Revision A2
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