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November 1994

INTEL CORPORATION 1995

Order Number 272356-003

8XL51FA FB FC

LOW VOLTAGE

CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLERS

Commercial Express

87L51FA 83L51FA 80L51FA 87L51FB 83L51FB 87L51FC 83L51FC

High Performance CHMOS OTP ROM
ROM CPU

Low Voltage Operation

20 MHz Commercial 16 MHz Express
Operation

Three 16-Bit Timer Counters

Programmable Counter Array with

High Speed Output
Compare Capture
Pulse Width Modulator
Watchdog Timer Capabilities

Up Down Timer Counter

Three Level Program Lock System

8K 16K 32K On-Chip Program Memory

256 Bytes of On-Chip Data RAM

Improved Quick Pulse Programming
Algorithm

Boolean Processor

32 Programmable I O Lines

7 Interrupt Sources

Four Level Interrupt Priority

Programmable Serial Channel with

Framing Error Detection
Automatic Address Recognition

64K External Program Memory Space

64K External Data Memory Space

MCS

51 Microcontroller Compatible

Instruction Set

Power Saving Idle and Power Down
Modes

ONCE (On-Circuit Emulation) Mode

Extended Temperature Range
(

40 C to

85 C)

MEMORY ORGANIZATION

Device

ROM

OTP ROM

Version

ROMLESS

Version

ROM

Bytes

RAM

OTP ROM

Bytes

83L51FA

87L51FA

80L51FA

256

83L51FB

87L51FB

80L51FA

16K

256

83L51FC

87L51FC

80L51FA

32K

256

These devices can address up to 64 Kbytes of external program data memory

The Intel 8XL51FA 8XL51FB 8XL51FC is a single-chip control oriented microcontroller which is fabricated on
Intel's reliable CHMOS III-E technology Being a member of the MCS

51 microcontroller family the

8XL51FA 8XL51FB 8XL51FC uses the same powerful instruction set has the same architecture and is pin-
for-pin compatible with the existing MCS 51 microcontroller products

The 8XL51FX is a 3V version of current 8XC51FX and will operate from 2 7V to 3 6V at a frequency range of
3 5 MHz to 16 MHz (Express) 20 MHz (Commercial)

For the remainder of this document the 8XL51FA 8XL51FB 8XL51FC will be referred to as the 8XL51FX
unless information applies to a specific device

8XL51FA FB FC

PIN DESCRIPTIONS

Supply voltage

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
inputs Port 0 pins that have 1's written to them float
and in that state can be used as high-impedance
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 emitting 1's and can source and
sink several inputs

Port 0 also receives the code bytes during OTP
ROM programming and outputs the code bytes dur-
ing program verification 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
several 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

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 8XL51FX

Port Pin

Alternate Function

P1 0

T2 (External Count Input to Timer
Counter 2) Clock Out

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
OTP ROM 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
several 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

on the data sheet) 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
addresses (MOVX

Ri) Port 2 emits the contents of

the P2 Special Function Register

Some Port 2 pins receive the high-order address bits
during OTP ROM programming and program verifi-
cation

Port 3 Port 3 is an 8-bit bidirectional I O port with
internal pullups The Port 3 output buffers can drive
several inputs Port 3 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 3
pins that are externally pulled low will source current
(I

on the data sheet) because of the pullups

Port 3 also serves the functions of various special
features of the MCS 51 microcontroller family as
listed below

Port Pin

Alternate Function

P3 0

RXD (serial input port)

P3 1

TXD (serial output port)

P3 2

INT0 (external interrupt 0)

P3 3

INT1 (external interrupt 1)

P3 4

T0 (Timer 0 external input)

P3 5

T1 (Timer 1 external input)

P3 6

WR (external data memory write strobe)

P3 7

RD (external data memory read strobe)

RST Reset input A high on this pin for two machine
cycles while the oscillator is running resets the de-
vice The port pins will be driven to their reset condi-
tion when a minimum V

IH2

voltage is applied wheth-

er the oscillator is running or not An internal pull-
down resistor permits a power-on reset with only a
capacitor connected to V

8XL51FA FB FC

ALE Address Latch Enable output pulse for latching
the low byte of the address during accesses to ex-
ternal memory This pin (ALE PROG) is also the
program pulse input during OTP ROM programming
for the 87L51FX

In normal operation ALE is emitted at a constant
rate of

the oscillator frequency and may be used

for external timing or clocking purposes Note how-
ever that one ALE pulse is skipped during each ac-
cess to external Data Memory

If desired ALE operation can be disabled by setting
bit 0 of SFR location 8EH With this bit set the pin is
weakly pulled high However the ALE disable fea-
ture will be suspended during a MOVX or MOVC in-
struction idle mode power down mode and ICE
mode The ALE disable feature will be terminated by
reset When the ALE disable feature is suspended or
terminated the ALE pin will no longer be pulled up
weakly Setting the ALE-disable bit has no affect if
the microcontroller is in external execution mode

Throughout the remainder of this data sheet ALE
will refer to the signal coming out of the ALE PROG
pin and the pin will be referred to as the ALE PROG
pin

PSEN Program Store Enable is the read strobe to
external Program Memory

When the 8XL51FX is executing code from external
Program Memory PSEN is activated twice each ma-
chine cycle except that two PSEN activations are
skipped during each access to external Data Memo-
ry

EA V

External Access enable

EA must be

strapped to VSS in order to enable the device to
fetch code from external Program Memory locations
0000H to 0FFFH Note however that if either of the
Program Lock bits are programmed EA will be inter-
nally latched on reset

EA must be strapped to V

for internal program

executions

This pin also receives the programming supply volt-
age (V

) during OTP ROM programming

XTAL1 Input to the inverting oscillator amplifier

XTAL2 Output from the inverting oscillator amplifier

OSCILLATOR CHARACTERISTICS

XTAL1 and XTAL2 are the input and output respec-
tively of a inverting amplifier which can be config-
ured for use as an on-chip oscillator as shown in
Figure 3 Either a quartz crystal or ceramic resonator

may be used More detailed information concerning
the use of the on-chip oscillator is available in Appli-
cation Note AP-155 ``Oscillators for Microcontrol-
lers ''

To drive the device from an external clock source
XTAL1 should be driven while XTAL2 floats as
shown in Figure 4 There are no requirements on the
duty cycle of the external clock signal since the in-
put to the internal clocking circuitry is through a di-
vide-by-two flip-flop but minimum and maximum
high and low times specified on the data sheet must
be observed

An external oscillator may encounter as much as a
100 pF load at XTAL1 when it starts up This is due
to interaction between the amplifier and its feedback
capacitance Once the external signal meets the V

and V

specifications the capacitance will not ex-

ceed 20 pF

272356 � 4

C1 C2 e 30 pF

10 pF for Crystals

For Ceramic Resonators contact resonator manufacturer

Figure 3 Oscillator Connections

272356 � 5

Figure 4 External Clock Drive Configuration

IDLE MODE

The user's software can invoke the Idle Mode When
the microcontroller is in this mode power consump-
tion is reduced The Special Function Registers and
the onboard RAM retain their values during Idle but
the processor stops executing instructions

Idle

Mode will be exited if the chip is reset or if an en-
abled interrupt occurs The PCA timer counter can
optionally be left running or paused during Idle
Mode

Электронный компонент: 83L51FA