80C51FA Datasheet, PDF (4/13 Pages) Intel Corporation – EVENT-CONTROL CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLER

AUTOMOTIVE 80C51FA 83C51FA
PIN DESCRIPTIONS
V_CC Supply voltage
V_SS Circuit ground
Port 0 Port 0 is an 8-bit open drain bidirectional
I O port As an output port each pin can sink several
LS TTL inputs Port 0 pins that have 1’s written to
them float and in that state can be used as high-im-
pedance inputs
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 emitting1’s and can source and
sink several LS TTL inputs
Port 0 outputs the code bytes during program verifi-
cation External pullup resistors are required 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
(I_IL on the datasheet) because of the internal pull-
ups
In addition Port 1 serves the functions of the follow-
ing special features of the 83C51FA
Port Pin
P1 0
P1 1
P1 2
P1 3
P1 4
P1 5
P1 6
P1 7
Alternate Function
T2 (External Count Input to Timer
Counter 2)
T2EX (Timer Counter 2 Capture
Reload Trigger and Direction Control)
ECI (External Count Input to the PCA)
CEX0 (External I O for Compare
Capture Module 0)
CEX1 (External I O for Compare
Capture Module 1)
CEX2 (External I O for Compare
Capture Module 2)
CEX3 (External I O for Compare
Capture Module 3)
CEX4 (External I O for Compare
Capture Module 4)
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
(I_IL on the datasheet) because of the internal pull-
ups
Port 2 emits the high-order address byte during
fetches from external Program Memory and during
accesses to external Data Memory that use 16-bit
addresses (MOVX DPTR) In this application it
uses strong internal pullups when emitting 1’s Dur-
ing accesses to external Data Memory that use 8-bit
Pin (PDIP)
Pad (PLCC)
270501 – 3
Do not connect reserved pins
Diagrams are for pin reference only Package sizes are not to scale
Figure 3 Pin Connections
270501 – 4
4