These devices can address up to 64 Kbytes of external program data memory
The Intel 87C51FA 8XC51FB 8XC51FC is a single-chip control oriented microcontroller which is fabricated on
Intel’s reliable CHMOS III-E technology The Intel 83C51FA 80C51FA is fabricated on CHMOS III technology
Being a member of the MCS 51 controller family the 8XC51FA 8XC51FB 8XC51FC uses the same powerful
instruction set has the same architecture and is pin-for-pin compatible with the existing MCS 51 controller
products The 8XC51FA 8XC51FB 8XC51FC is an enhanced version of the 8XC52 8XC54 8XC58 Its added
features make it an even more powerful microcontroller for applications that require Pulse Width Modulation
High Speed I O and up down counting capabilities such as motor control
For the remainder of this document the 8XC51FA 8XC51FB 8XC51FC will be referred to as the 8XC51FX
unless information applies to a specific device
Other brands and names are the property of their respective owners
Information in this document is provided in connection with Intel products Intel assumes no liability whatsoever including infringement of any patent or
copyright for sale and use of Intel products except as provided in Intel’s Terms and Conditions of Sale for such products Intel retains the right to make
changes to these specifications at any time without notice Microcomputer Products may have minor variations to this specification known as errata
COPYRIGHT
INTEL CORPORATION 1995
December 1995
Order Number 272322-003
8XC51FX
Table 1 Proliferation Options
Standard
1
80C51FA
83C51FA
87C51FA
83C51FB
87C51FB
83C51FC
87C51FC
NOTES
1
35
-1
35
-2
05
-24
35
-33
35
MHz
MHz
MHz
MHz
MHz
to
to
to
to
to
12
16
12
24
33
MHz
MHz
MHz
MHz
MHz
5V
5V
5V
5V
5V
g
20%
g
20%
g
20%
g
20%
g
10%
-1
X
X
X
X
X
X
X
-2
X
X
X
X
X
X
X
-24
X
X
X
X
X
X
X
-33
X
X
X
X
X
X
X
X
X
X
X
X
X
X
272322 –1
Figure 1 8XC51FX Block Diagram
2
8XC51FX
PROCESS INFORMATION
The 87C51FA 8XC51FB 8XC51FC is manufactured
on P629 0 a CHMOS III-E process Additional pro-
cess and reliability information is available in Intel’s
Components Quality and Reliability Handbook
Or-
der No 210997
PACKAGES
Part
8XC51FX
Prefix
P
D
N
S
Package Type
40-Pin Plastic DIP
40-Pin CERDIP
44-Pin PLCC
44-Pin QFP
272322 –23
PLCC
272322 – 2
DIP
272322 – 24
Do not connect Reserved Pins
QFP
Figure 2 Pin Connections
3
8XC51FX
In addition Port 1 serves the functions of the follow-
ing special features of the 8XC51FX
Port Pin
V
SS
Circuit ground
V
SS1
Secondary ground (not on DIP devices or any
83C51FA 80C51FA device) Provided to reduce
ground bounce and improve power supply by-pass-
ing
NOTE
This pin is not a substitution for the V
SS
pin (Con-
nection not necessary for proper operation )
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 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
(I
IL
on the data sheet) because of the internal pull-
ups
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) Clock Out
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)
PIN DESCRIPTIONS
V
CC
Supply voltage
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
(I
IL
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 EPROM programming and program verifica-
tion
Port 3
Port 3 is an 8-bit bidirectional I O port with
internal pullups The Port 3 output buffers can drive
LS TTL 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
IL
on the data sheet) because of the pullups
4
8XC51FX
Port 3 also serves the functions of various special
features of the MCS-51 Family as listed below
Port Pin
P3 0
P3 1
P3 2
P3 3
P3 4
P3 5
P3 6
P3 7
Alternate Function
RXD (serial input port)
TXD (serial output port)
INT0 (external interrupt 0)
INT1 (external interrupt 1)
T0 (Timer 0 external input)
T1 (Timer 1 external input)
WR (external data memory write strobe)
RD (external data memory read strobe)
When the 8XC51FX 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
PP
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 should be strapped to V
CC
for internal program
executions
This pin also receives the programming supply volt-
age (V
PP
) during EPROM programming
XTAL1
Input to the inverting oscillator amplifier
XTAL2
Output from the inverting oscillator amplifi-
er
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
IH1
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
CC
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 EPROM programming for
the 87C51FX
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
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
divide-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
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