AUTOMOTIVE 87C51FA/FB/FC/FC-20
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 inter-
nal pullups when emitting 1's, and can source and
sink several LS TTL inputs.
Port 0 also receives the code bytes during EPROM
programming, and outputs the code bytes during
program verification. External pullup resistors are re-
quired during program verification.
Port 1
: Port 1 is an 8-bit bidirectional I/O port with
internal pullups. The Port 1 output buffers can drive
LS TTL inputs. Port 1 pins that have 1's written to
them are pulled high by the internal pullups, and in
that state can be used as inputs. As inputs, Port 1
pins that are externally pulled low will source current
(IIL, on the data sheet) because of the internal pull-
ups.
In addition, Port 1 serves the functions of the follow-
ing special features of the 87C51FB/FC:
Port Pin
Alternate Function
P1.0
T2 (External Count Input to
Timer/Counter 2)
P1.1
T2EX (Timer/Counter 2 Capture/
Reload Trigger and Direction Control)
P1.2
ECI (External Count Input to the PCA)
P1.3
CEX0 (External I/O for Compare/
Capture Module 0)
P1.4
CEX1 (External I/O for Compare/
Capture Module 1)
P1.5
CEX2 (External I/O for Compare/
Capture Module 2)
P1.6
CEX3 (External I/O for Compare/
Capture Module 3)
P1.7
CEX4 (External I/O for Compare/
Capture Module 4)
Port 1 receives the low-order address bytes during
EPROM programming and verifying.
Port 2
: Port 2 is an 8-bit bidirectional I/O port with
internal pullups. The Port 2 output buffers can drive
LS TTL inputs. Port 2 pins that have 1's written to
them are pulled high by the internal pullups, and in
that state can be used as inputs. As inputs, Port 2
pins that are externally pulled low will source current
(IIL, on the data sheet) because of the internal pull-
ups.
PACKAGES
Part
Package Type
87C51FA/FB/FC
40-Pin Plastic DIP
44-Pin PLCC
DIP
270961±3
PAD (PLCC)
270961±4
*
EPROM only
**Do not connect reserved pins.
Diagrams are for pin reference only. Package sizes are
not to scale.
Figure 3. Pin Connections (Top View)
4