PHILIPS P80C31SBPN

INTEGRATED CIRCUITS
80C51/87C51/80C31
80C51 8-bit microcontroller family
4K/128 OTP/ROM/ROMless low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
Product specification
Supersedes data of 1999 Apr 01
IC28 Data Handbook
2000 Jan 20
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
DESCRIPTION
FEATURES
• 8051 Central Processing Unit
The Philips 8XC51/31 is a high-performance static 80C51 design
fabricated with Philips high-density CMOS technology with operation
from 2.7V to 5.5V.
– 4k × 8 ROM (80C51)
– 128 × 8 RAM
The 8XC51/31 contains a 4k × 8 ROM, a 128 × 8 RAM, 32 I/O lines,
three 16-bit counter/timers, a six-source, four-priority level nested
interrupt structure, a serial I/O port for either multi-processor
communications, I/O expansion or full duplex UART, and on-chip
oscillator and clock circuits.
– Three 16-bit counter/timers
– Boolean processor
– Full static operation
– Low voltage (2.7V to 5.5V@ 16MHz) operation
• Memory addressing capability
In addition, the device is a low power static design which offers a
wide range of operating frequencies down to zero. Two software
selectable modes of power reduction—idle mode and power-down
mode are available. The idle mode freezes the CPU while allowing
the RAM, timers, serial port, and interrupt system to continue
functioning. The power-down mode saves the RAM contents but
freezes the oscillator, causing all other chip functions to be
inoperative. Since the design is static, the clock can be stopped
without loss of user data and then the execution resumed from the
point the clock was stopped.
– 64k ROM and 64k RAM
• Power control modes:
– Clock can be stopped and resumed
– Idle mode
– Power-down mode
• CMOS and TTL compatible
• TWO speed ranges at VCC = 5V
SELECTION TABLE
– 0 to 16MHz
For applications requiring more ROM and RAM,
see the 8XC52/54/58/80C32, 8XC51FA/FB/FC/80C51FA,
and 8XC51RA+/RB+/RC+/80C51RA+ data sheet.
– 0 to 33MHz
ROM/EPROM
Memory Size
(X by 8)
RAM Size
(X by 8)
Programmable
Timer Counter
(PCA)
Hardware
Watch Dog
Timer
128
No
No
• Three package styles
• Extended temperature ranges
• Dual Data Pointers
• Security bits:
80C31/8XC51
0K/4K
– ROM (2 bits)
– OTP/EPROM (3 bits)
• Encryption array—64 bytes
• 4 level priority interrupt
• 6 interrupt sources
• Four 8-bit I/O ports
• Full–duplex enhanced UART
80C32/8XC52/54/58
0K/8K/16K/32K
256
No
No
Yes
No
Yes
Yes
80C51FA/8XC51FA/FB/FC
0K/8K/16K/32K
256
80C51RA+/8XC51RA+/RB+/RC+
0K/8K/16K/32K
512
– Framing error detection
– Automatic address recognition
8XC51RD+
64K
2000 Jan 20
1024
Yes
• Programmable clock out
• Asynchronous port reset
• Low EMI (inhibit ALE)
• Wake-up from Power Down by an external interrupt (8XC51)
Yes
2
853–0169 23001
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
80C51/87C51 AND 80C31 ORDERING INFORMATION
TEMPERATURE RANGE °C
AND PACKAGE
VOLTAGE
RANGE
FREQ.
(MHz)
DWG.
#
P80C31SBPN
0 to +70
+70, Plastic Dual In
In-line
line Package
2 7V to 5
2.7V
5.5V
5V
0 to 16
SOT129 1
SOT129-1
P80C31SBAA
+70 Plastic Leaded Chip Carrier
0 to +70,
2 7V to 5
5V
2.7V
5.5V
0 to 16
SOT187 2
SOT187-2
P80C31SBBB
0 to +70
+70, Plastic Quad Flat Pack
2 7V to 5
2.7V
5.5V
5V
0 to 16
SOT307 2
SOT307-2
P80C31SFP N
–40
40 to +85
+85, Plastic Dual In
In-line
line Package
2 7V to 5
2.7V
5.5V
5V
0 to 16
SOT129 1
SOT129-1
P80C31SFA A
–40
40 to +85,
+85 Plastic Leaded Chip Carrier
2 7V to 5
2.7V
5.5V
5V
0 to 16
SOT187 2
SOT187-2
P80C31SFB B
–40
40 to +85
+85, Plastic Quad Flat Pack
2 7V to 5
2.7V
5.5V
5V
0 to 16
SOT307 2
SOT307-2
P80C31UBAA
0 to +70,
+70 Plastic Leaded Chip Carrier
5V
0 to 33
SOT187 2
SOT187-2
P80C31UBPN
0 to +70
+70, Plastic Dual In
In-line
line Package
5V
0 to 33
SOT129 1
SOT129-1
P80C31UBBB
0 to +70
+70, Plastic Quad Flat Pack
5V
0 to 33
SOT307 2
SOT307-2
P80C31UFA A
–40
40 to +85,
+85 Plastic Leaded Chip Carrier
5V
0 to 33
SOT187 2
SOT187-2
P80C31UFPN
–40
40 to +85
+85, Plastic Dual In
In-line
line Package
5V
0 to 33
SOT129 1
SOT129-1
P80C31UFBB
–40
40 to +85
+85, Plastic Quad Flat Pack
5V
0 to 33
SOT307 2
SOT307-2
MEMORY SIZE
4K × 8
ROM
P80C51SBPN
OTP
P87C51SBPN
ROM
P80C51SBAA
OTP
P87C51SBAA
ROM
P80C51SBBB
OTP
P87C51SBBB
ROM
P80C51SFP N
OTP
P87C51SFP N
ROM
P80C51SFA A
OTP
P87C51SFA A
ROM
P80C51SFB B
OTP
P87C51SFB B
ROM
P80C51UBAA
OTP
P87C51UBAA
ROM
P80C51UBPN
OTP
P87C51UBPN
ROM
P80C51UBBB
OTP
P87C51UBBB
ROM
P80C51UFA A
OTP
P87C51UFA A
ROM
P80C51UFPN
OTP
P87C51UFPN
ROM
P80C51UFBB
OTP
P87C51UFBB
ROMless
80C51/87C51 AND 80C31 ORDERING INFORMATION
DEVICE NUMBER (P87C51)
OPERATING FREQUENCY, MAX (S)
TEMPERATURE RANGE (B)
PACKAGE (AA)
P80C51 ROM
S = 16 MHz
B = 0_ to +70_C
AA = PLCC
P87C51 OTP
U = 33 MHz
F = –40_C to +85_C
BB = PQFP
P80C31 ROMless
2000 Jan 20
PN = PDIP
3
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
BLOCK DIAGRAM
P0.0–P0.7
P2.0–P2.7
PORT 0
DRIVERS
PORT 2
DRIVERS
VCC
VSS
RAM ADDR
REGISTER
PORT 0
LATCH
RAM
PORT 2
LATCH
ROM/EPROM
8
B
REGISTER
STACK
POINTER
ACC
PROGRAM
ADDRESS
REGISTER
TMP1
TMP2
BUFFER
ALU
SFRs
PC
INCREMENTER
TIMERS
PSW
8
16
PSEN
ALE/PROG
EAVPP
TIMING
AND
CONTROL
RST
INSTRUCTION
REGISTER
PROGRAM
COUNTER
PD
DPTR’S
MULTIPLE
PORT 1
LATCH
PORT 3
LATCH
PORT 1
DRIVERS
PORT 3
DRIVERS
P1.0–P1.7
P3.0–P3.7
OSCILLATOR
XTAL1
XTAL2
SU00845
2000 Jan 20
4
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
LOGIC SYMBOL
PLASTIC LEADED CHIP CARRIER PIN FUNCTIONS
VCC
6
VSS
XTAL1
1
40
7
39
PORT 0
ADDRESS AND
DATA BUS
LCC
XTAL2
17
PORT 1
T2
T2EX
RST
EA/VPP
18
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
RxD
TxD
INT0
INT1
T0
T1
WR
RD
PORT 2
ALE/PROG
PORT 3
SECONDARY FUNCTIONS
PSEN
29
ADDRESS BUS
SU00830
PIN CONFIGURATIONS
Function
NIC*
P1.0/T2
P1.1/T2EX
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
RST
P3.0/RxD
NIC*
P3.1/TxD
P3.2/INT0
P3.3/INT1
Pin
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
28
Function
P3.4/T0
P3.5/T1
P3.6/WR
P3.7/RD
XTAL2
XTAL1
VSS
NIC*
P2.0/A8
P2.1/A9
P2.2/A10
P2.3/A11
P2.4/A12
P2.5/A13
P2.6/A14
Pin
31
32
33
34
35
36
37
38
39
40
41
42
43
44
* NO INTERNAL CONNECTION
T2/P1.0 1
40 VCC
T2EX/P1.1 2
39 P0.0/AD0
P1.2 3
38 P0.1/AD1
P1.3 4
37 P0.2/AD2
P1.4 5
36 P0.3/AD3
P1.5 6
35 P0.4/AD4
P1.6 7
34 P0.5/AD5
P1.7 8
33 P0.6/AD6
RST 9
32 P0.7/AD7
SU01062
PLASTIC QUAD FLAT PACK
PIN FUNCTIONS
44
34
1
RxD/P3.0 10
TxD/P3.1 11
DUAL
IN-LINE
PACKAGE
33
PQFP
11
23
31 EA/VPP
12
30 ALE
INT0/P3.2 12
29 PSEN
INT1/P3.3 13
28 P2.7/A15
T0/P3.4 14
27 P2.6/A14
T1/P3.5 15
26 P2.5/A13
WR/P3.6 16
25 P2.4/A12
RD/P3.7 17
24 P2.3/A11
XTAL2 18
23 P2.2/A10
XTAL1 19
22 P2.1/A9
VSS 20
21 P2.0/A8
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Function
P1.5
P1.6
P1.7
RST
P3.0/RxD
NIC*
P3.1/TxD
P3.2/INT0
P3.3/INT1
P3.4/T0
P3.5/T1
P3.6/WR
P3.7/RD
XTAL2
XTAL1
Pin
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
* NO INTERNAL CONNECTION
SU01063
2000 Jan 20
Function
P2.7/A15
PSEN
ALE
NIC*
EA/VPP
P0.7/AD7
P0.6/AD6
P0.5/AD5
P0.4/AD4
P0.3/AD3
P0.2/AD2
P0.1/AD1
P0.0/AD0
VCC
5
22
Function
VSS
NIC*
P2.0/A8
P2.1/A9
P2.2/A10
P2.3/A11
P2.4/A12
P2.5/A13
P2.6/A14
P2.7/A15
PSEN
ALE
NIC*
EA/VPP
P0.7/AD7
Pin
31
32
33
34
35
36
37
38
39
40
41
42
43
44
Function
P0.6/AD6
P0.5/AD5
P0.4/AD4
P0.3/AD3
P0.2/AD2
P0.1/AD1
P0.0/AD0
VCC
NIC*
P1.0/T2
P1.1/T2EX
P1.2
P1.3
P1.4
SU01064
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
PIN DESCRIPTIONS
PIN NUMBER
MNEMONIC
DIP
LCC
QFP
TYPE
VSS
20
22
16
I
Ground: 0V reference.
VCC
40
44
38
I
Power Supply: This is the power supply voltage for normal, idle, and power-down operation.
39–32
43–36
37–30
I/O
Port 0: Port 0 is an open-drain, bidirectional I/O port. Port 0 pins that have 1s written to
them float and 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 internal pull-ups when emitting 1s. Port 0 also outputs the
code bytes during program verification and received code bytes during EPROM
programming. External pull-ups are required during program verification.
1–8
2–9
40–44,
1–3
I/O
1
2
2
3
40
41
I/O
I
Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. Port 1 pins that have 1s
written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs,
port 1 pins that are externally pulled low will source current because of the internal pull-ups.
(See DC Electrical Characteristics: IIL). Port 1 also receives the low-order address byte
during program memory verification. Alternate functions for Port 1 include:
T2 (P1.0): Timer/Counter 2 external count input/clockout (see Programmable Clock-Out).
T2EX (P1.1): Timer/Counter 2 Reload/Capture/Direction control.
P2.0–P2.7
21–28
24–31
18–25
I/O
Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. Port 2 pins that have 1s
written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs,
port 2 pins that are externally being pulled low will source current because of the internal
pull-ups. (See DC Electrical Characteristics: IIL). 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
pull-ups when emitting 1s. During accesses to external data memory that use 8-bit addresses
(MOV @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 verification.
P3.0–P3.7
10–17
11,
13–19
5,
7–13
I/O
10
11
12
13
14
15
16
17
11
13
14
15
16
17
18
19
5
7
8
9
10
11
12
13
I
O
I
I
I
I
O
O
Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins that have 1s
written to them are pulled high by the internal pull-ups and can be used as inputs. As inputs,
port 3 pins that are externally being pulled low will source current because of the pull-ups.
(See DC Electrical Characteristics: IIL). Port 3 also serves the special features of the 80C51
family, as listed below:
RxD (P3.0): Serial input port
TxD (P3.1): Serial output port
INT0 (P3.2): External interrupt
INT1 (P3.3): External interrupt
T0 (P3.4): Timer 0 external input
T1 (P3.5): Timer 1 external input
WR (P3.6): External data memory write strobe
RD (P3.7): External data memory read strobe
RST
9
10
4
I
Reset: A high on this pin for two machine cycles while the oscillator is running, resets the
device. An internal diffused resistor to VSS permits a power-on reset using only an external
capacitor to VCC.
ALE/PROG
30
33
27
O
Address Latch Enable/Program Pulse: Output pulse for latching the low byte of the
address during an access to external memory. In normal operation, ALE is emitted at a
constant rate of 1/6 the oscillator frequency, and can be used for external timing or clocking.
Note that one ALE pulse is skipped during each access to external data memory. This pin is
also the program pulse input (PROG) during EPROM programming. ALE can be disabled by
setting SFR auxiliary.0. With this bit set, ALE will be active only during a MOVX instruction.
PSEN
29
32
26
O
Program Store Enable: The read strobe to external program memory. When the 8XC51/31
is executing code from the external program memory, PSEN is activated twice each
machine cycle, except that two PSEN activations are skipped during each access to
external data memory. PSEN is not activated during fetches from internal program memory.
EA/VPP
31
35
29
I
External Access Enable/Programming Supply Voltage: EA must be externally held low
to enable the device to fetch code from external program memory locations 0000H and
0FFFH. If EA is held high, the device executes from internal program memory unless the
program counter contains an address greater than 0FFFH. This pin also receives the
12.75V programming supply voltage (VPP) during EPROM programming. If security bit 1 is
programmed, EA will be internally latched on Reset.
XTAL1
19
21
15
I
Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock generator
circuits.
P0.0–0.7
P1.0–P1.7
NAME AND FUNCTION
XTAL2
18
20
14
O
Crystal 2: Output from the inverting oscillator amplifier.
NOTE:
To avoid “latch-up” effect at power-on, the voltage on any pin at any time must not be higher than VCC + 0.5V or VSS – 0.5V, respectively.
2000 Jan 20
6
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
Table 1.
SYMBOL
8XC51/80C31 Special Function Registers
DESCRIPTION
DIRECT
ADDRESS
BIT ADDRESS, SYMBOL, OR ALTERNATIVE PORT FUNCTION
MSB
LSB
RESET
VALUE
ACC*
Accumulator
E0H
E7
E6
E5
E4
E3
E2
E1
E0
00H
AUXR#
Auxiliary
8EH
–
–
–
–
–
–
–
AO
xxxxxxx0B
AUXR1#
Auxiliary 1
A2H
–
–
–
LPEP2
WUPD3
0
–
DPS
xxx000x0B
B*
B register
F0H
F7
F6
F5
F4
F3
F2
F1
F0
DPTR:
DPH
DPL
Data Pointer (2 bytes)
Data Pointer High
Data Pointer Low
83H
82H
IE*
Interrupt Enable
A8H
IP*
IPH#
P0*
P1*
P2*
Interrupt Priority
Interrupt Priority High
Port 0
Port 1
Port 2
B8H
B7H
80H
90H
A0H
00H
00H
00H
AF
AE
AD
AC
AB
AA
A9
A8
EA
–
ET2
ES
ET1
EX1
ET0
EX0
BF
BE
BD
BC
BB
BA
B9
B8
–
–
PT2
PS
PT1
PX1
PT0
PX0
B7
B6
B5
B4
B3
B2
B1
B0
–
–
PT2H
PSH
PT1H
PX1H
PT0H
PX0H
87
86
85
84
83
82
81
80
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
97
96
95
94
93
92
91
90
0x000000B
xx000000B
xx000000B
FFH
–
–
–
–
–
–
T2EX
T2
A7
A6
A5
A4
A3
A2
A1
A0
AD15
AD14
AD13
AD12
AD11
AD10
AD9
AD8
B7
B6
B5
B4
B3
B2
B1
B0
T1
T0
INT1
INT0
TxD
RxD
FFH
00xx0000B
P3*
Port 3
B0H
RD
WR
PCON#1
Power Control
87H
SMOD1
SMOD0
–
POF
GF1
GF0
PD
IDL
D7
D6
D5
D4
D3
D2
D1
D0
CY
AC
F0
RS1
RS0
OV
–
P
FFH
FFH
PSW*
Program Status Word
D0H
RACAP2H#
RACAP2L#
Timer 2 Capture High
Timer 2 Capture Low
CBH
CAH
00H
00H
SADDR#
SADEN#
Slave Address
Slave Address Mask
A9H
B9H
00H
00H
SBUF
Serial Data Buffer
99H
SCON*
Serial Control
98H
SP
Stack Pointer
81H
TCON*
Timer Control
88H
xxxxxxxxB
9F
9E
9D
9C
9B
9A
99
98
SM0/FE
SM1
SM2
REN
TB8
RB8
TI
RI
8F
8E
8D
8C
8B
8A
89
88
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
CF
CE
CD
CC
CB
CA
C9
C8
00H
07H
T2CON*
Timer 2 Control
C8H
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/RL2
T2MOD#
TH0
TH1
TH2#
TL0
TL1
TL2#
Timer 2 Mode Control
Timer High 0
Timer High 1
Timer High 2
Timer Low 0
Timer Low 1
Timer Low 2
C9H
8CH
8DH
CDH
8AH
8BH
CCH
–
–
–
–
–
–
T2OE
DCEN
M1
M0
GATE
C/T
M1
M0
TMOD
Timer Mode
89H
GATE
C/T
* SFRs are bit addressable.
# SFRs are modified from or added to the 80C51 SFRs.
– Reserved bits.
1. Reset value depends on reset source.
2. LPEP – Low Power EPROM operation (OTP/EPROM only)
3. Not available on 80C31.
2000 Jan 20
000000x0B
7
00H
00H
xxxxxx00B
00H
00H
00H
00H
00H
00H
00H
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
interrupt allows both the SFRs and the on-chip RAM to retain their
values. WUPD (AUXR1.3–Wakeup from Power Down) enables or
disables the wakeup from power down with external interrupt.
Where:
OSCILLATOR CHARACTERISTICS
XTAL1 and XTAL2 are the input and output, respectively, of an
inverting amplifier. The pins can be configured for use as an on-chip
oscillator, as shown in the logic symbol.
WUPD = 0 Disable
WUPD = 1 Enable
To drive the device from an external clock source, XTAL1 should be
driven while XTAL2 is left unconnected. There are no requirements
on the duty cycle of the external clock signal, because the input to
the internal clock circuitry is through a divide-by-two flip-flop.
However, minimum and maximum high and low times specified in
the data sheet must be observed.
To properly terminate Power Down the reset or external interrupt
should not be executed before VCC is restored to its normal
operating level and must be held active long enough for the
oscillator to restart and stabilize (normally less than 10ms).
With an external interrupt, INT0 or INT1 must be enabled and
configured as level-sensitive. Holding the pin low restarts the
oscillator but bringing the pin back high completes the exit. Once the
interrupt is serviced, the next instruction to be executed after RETI
will be the one following the instruction that put the device into
Power Down.
Reset
A reset is accomplished by holding the RST pin high for at least two
machine cycles (24 oscillator periods), while the oscillator is running.
To insure a good power-up reset, the RST pin must be high long
enough to allow the oscillator time to start up (normally a few
milliseconds) plus two machine cycles.
For the 80C31, wakeup from power down is always enabled.
Stop Clock Mode
The static design enables the clock speed to be reduced down to
0 MHz (stopped). When the oscillator is stopped, the RAM and
Special Function Registers retain their values. This mode allows
step-by-step utilization and permits reduced system power
consumption by lowering the clock frequency down to any value. For
lowest power consumption the Power Down mode is suggested.
LPEP
Idle Mode
Design Consideration
The eprom array contains some analog circuits that are not required
when VCC is less than 4V, but are required for a VCC greater than
4V. The LPEP bit (AUXR.4), when set, will powerdown these analog
circuits resulting in a reduced supply current. This bit should be set
ONLY for applications that operate at a VCC less tan 4V.
• When the idle mode is terminated by a hardware reset, the device
In idle mode (see Table 2), the CPU puts itself to sleep while all of
the on-chip peripherals stay active. The instruction to invoke the idle
mode is the last instruction executed in the normal operating mode
before the idle mode is activated. The CPU contents, the on-chip
RAM, and all of the special function registers remain intact during
this mode. The idle mode can be terminated either by any enabled
interrupt (at which time the process is picked up at the interrupt
service routine and continued), or by a hardware reset which starts
the processor in the same manner as a power-on reset.
normally resumes program execution, from where it left off, up to
two machine cycles before the internal reset algorithm takes
control. On-chip hardware inhibits access to internal RAM in this
event, but access to the port pins is not inhibited. To eliminate the
possibility of an unexpected write when Idle is terminated by reset,
the instruction following the one that invokes Idle should not be
one that writes to a port pin or to external memory.
ONCE Mode
Power-Down Mode
The ONCE (“On-Circuit Emulation”) Mode facilitates testing and
debugging of systems without the device having to be removed from
the circuit. The ONCE Mode is invoked by:
To save even more power, a Power Down mode (see Table 2) can
be invoked by software. In this mode, the oscillator is stopped and
the instruction that invoked Power Down is the last instruction
executed. The on-chip RAM and Special Function Registers retain
their values down to 2.0V and care must be taken to return VCC to
the minimum specified operating voltages before the Power Down
Mode is terminated.
1. Pull ALE low while the device is in reset and PSEN is high;
2. Hold ALE low as RST is deactivated.
While the device is in ONCE Mode, the Port 0 pins go into a float
state, and the other port pins and ALE and PSEN are weakly pulled
high. The oscillator circuit remains active. While the 8XC51/31 is in
this mode, an emulator or test CPU can be used to drive the circuit.
Normal operation is restored when a normal reset is applied.
For the 87C51 and 80C51 either a hardware reset or external
interrupt can be used to exit from Power Down. Reset redefines all
the SFRs but does not change the on-chip RAM. An external
Table 2. External Pin Status During Idle and Power-Down Modes
PROGRAM MEMORY
ALE
PSEN
PORT 0
PORT 1
PORT 2
PORT 3
Idle
MODE
Internal
1
1
Data
Data
Data
Data
Idle
External
1
1
Float
Data
Address
Data
Power-down
Internal
0
0
Data
Data
Data
Data
Power-down
External
0
0
Float
Data
Data
Data
2000 Jan 20
8
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
TH2, to be captured into registers RCAP2L and RCAP2H,
respectively. In addition, the transition at T2EX causes bit EXF2 in
T2CON to be set, and EXF2 like TF2 can generate an interrupt
(which vectors to the same location as Timer 2 overflow interrupt.
The Timer 2 interrupt service routine can interrogate TF2 and EXF2
to determine which event caused the interrupt). The capture mode is
illustrated in Figure 2 (There is no reload value for TL2 and TH2 in
this mode. Even when a capture event occurs from T2EX, the
counter keeps on counting T2EX pin transitions or osc/12 pulses.).
Programmable Clock-Out
A 50% duty cycle clock can be programmed to come out on P1.0.
This pin, besides being a regular I/O pin, has two alternate
functions. It can be programmed:
1. to input the external clock for Timer/Counter 2, or
2. to output a 50% duty cycle clock ranging from 61Hz to 4MHz at a
16MHz operating frequency.
To configure the Timer/Counter 2 as a clock generator, bit C/T2 (in
T2CON) must be cleared and bit T20E in T2MOD must be set. Bit
TR2 (T2CON.2) also must be set to start the timer.
Auto-Reload Mode (Up or Down Counter)
In the 16-bit auto-reload mode, Timer 2 can be configured (as either
a timer or counter (C/T2* in T2CON)) then programmed to count up
or down. The counting direction is determined by bit DCEN(Down
Counter Enable) which is located in the T2MOD register (see
Figure 3). When reset is applied the DCEN=0 which means Timer 2
will default to counting up. If DCEN bit is set, Timer 2 can count up
or down depending on the value of the T2EX pin.
The Clock-Out frequency depends on the oscillator frequency and
the reload value of Timer 2 capture registers (RCAP2H, RCAP2L)
as shown in this equation:
4
Oscillator Frequency
(65536 * RCAP2H, RCAP2L)
Where:
Figure 4 shows Timer 2 which will count up automatically since
DCEN=0. In this mode there are two options selected by bit EXEN2
in T2CON register. If EXEN2=0, then Timer 2 counts up to 0FFFFH
and sets the TF2 (Overflow Flag) bit upon overflow. This causes the
Timer 2 registers to be reloaded with the 16-bit value in RCAP2L
and RCAP2H. The values in RCAP2L and RCAP2H are preset by
software means.
(RCAP2H,RCAP2L) = the content of RCAP2H and RCAP2L
taken as a 16-bit unsigned integer.
In the Clock-Out mode Timer 2 roll-overs will not generate an
interrupt. This is similar to when it is used as a baud-rate generator.
It is possible to use Timer 2 as a baud-rate generator and a clock
generator simultaneously. Note, however, that the baud-rate and the
Clock-Out frequency will be the same.
If EXEN2=1, then a 16-bit reload can be triggered either by an
overflow or by a 1-to-0 transition at input T2EX. This transition also
sets the EXF2 bit. The Timer 2 interrupt, if enabled, can be
generated when either TF2 or EXF2 are 1.
TIMER 2 OPERATION
In Figure 5 DCEN=1 which enables Timer 2 to count up or down.
This mode allows pin T2EX to control the direction of count. When a
logic 1 is applied at pin T2EX Timer 2 will count up. Timer 2 will
overflow at 0FFFFH and set the TF2 flag, which can then generate
an interrupt, if the interrupt is enabled. This timer overflow also
causes the 16–bit value in RCAP2L and RCAP2H to be reloaded
into the timer registers TL2 and TH2.
Timer 2
Timer 2 is a 16-bit Timer/Counter which can operate as either an
event timer or an event counter, as selected by C/T2* in the special
function register T2CON (see Figure 1). Timer 2 has three operating
modes:Capture, Auto-reload (up or down counting) ,and Baud Rate
Generator, which are selected by bits in the T2CON as shown in
Table 3.
When a logic 0 is applied at pin T2EX this causes Timer 2 to count
down. The timer will underflow when TL2 and TH2 become equal to
the value stored in RCAP2L and RCAP2H. Timer 2 underflow sets
the TF2 flag and causes 0FFFFH to be reloaded into the timer
registers TL2 and TH2.
Capture Mode
In the capture mode there are two options which are selected by bit
EXEN2 in T2CON. If EXEN2=0, then timer 2 is a 16-bit timer or
counter (as selected by C/T2* in T2CON) which, upon overflowing
sets bit TF2, the timer 2 overflow bit. This bit can be used to
generate an interrupt (by enabling the Timer 2 interrupt bit in the
IE register). If EXEN2= 1, Timer 2 operates as described above, but
with the added feature that a 1- to -0 transition at external input
T2EX causes the current value in the Timer 2 registers, TL2 and
The external flag EXF2 toggles when Timer 2 underflows or
overflows. This EXF2 bit can be used as a 17th bit of resolution if
needed. The EXF2 flag does not generate an interrupt in this mode
of operation.
Table 3. Timer 2 Operating Modes
RCLK + TCLK
CP/RL2
TR2
0
0
1
16-bit Auto-reload
0
1
1
16-bit Capture
1
X
1
Baud rate generator
X
X
0
(off)
2000 Jan 20
MODE
9
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
(MSB)
(LSB)
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/RL2
Symbol
Position
Name and Significance
TF2
T2CON.7
EXF2
T2CON.6
RCLK
T2CON.5
TCLK
T2CON.4
EXEN2
T2CON.3
TR2
C/T2
T2CON.2
T2CON.1
CP/RL2
T2CON.0
Timer 2 overflow flag set by a Timer 2 overflow and must be cleared by software. TF2 will not be set
when either RCLK or TCLK = 1.
Timer 2 external flag set when either a capture or reload is caused by a negative transition on T2EX and
EXEN2 = 1. When Timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU to vector to the Timer 2
interrupt routine. EXF2 must be cleared by software. EXF2 does not cause an interrupt in up/down
counter mode (DCEN = 1).
Receive clock flag. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock
in modes 1 and 3. RCLK = 0 causes Timer 1 overflow to be used for the receive clock.
Transmit clock flag. When set, causes the serial port to use Timer 2 overflow pulses for its transmit clock
in modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock.
Timer 2 external enable flag. When set, allows a capture or reload to occur as a result of a negative
transition on T2EX if Timer 2 is not being used to clock the serial port. EXEN2 = 0 causes Timer 2 to
ignore events at T2EX.
Start/stop control for Timer 2. A logic 1 starts the timer.
Timer or counter select. (Timer 2)
0 = Internal timer (OSC/12)
1 = External event counter (falling edge triggered).
Capture/Reload flag. When set, captures will occur on negative transitions at T2EX if EXEN2 = 1. When
cleared, auto-reloads will occur either with Timer 2 overflows or negative transitions at T2EX when
EXEN2 = 1. When either RCLK = 1 or TCLK = 1, this bit is ignored and the timer is forced to auto-reload
on Timer 2 overflow.
SU00728
Figure 1. Timer/Counter 2 (T2CON) Control Register
OSC
÷ 12
C/T2 = 0
TL2
(8-bits)
TH2
(8-bits)
TF2
C/T2 = 1
T2 Pin
Control
TR2
Capture
Transition
Detector
Timer 2
Interrupt
RCAP2L
RCAP2H
T2EX Pin
EXF2
Control
EXEN2
SU00066
Figure 2. Timer 2 in Capture Mode
2000 Jan 20
10
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
T2MOD
Address = 0C9H
Reset Value = XXXX XX00B
Not Bit Addressable
Bit
*
—
—
—
—
—
—
T2OE
DCEN
7
6
5
4
3
2
1
0
Symbol
Function
—
Not implemented, reserved for future use.*
T2OE
Timer 2 Output Enable bit.
DCEN
Down Count Enable bit. When set, this allows Timer 2 to be configured as an up/down counter.
User software should not write 1s to reserved bits. These bits may be used in future 8051 family products to invoke new features.
In that case, the reset or inactive value of the new bit will be 0, and its active value will be 1. The value read from a reserved bit is
indeterminate.
SU00729
Figure 3. Timer 2 Mode (T2MOD) Control Register
OSC
÷ 12
C/T2 = 0
TL2
(8-BITS)
TH2
(8-BITS)
C/T2 = 1
T2 PIN
CONTROL
TR2
RELOAD
TRANSITION
DETECTOR
RCAP2L
RCAP2H
TF2
TIMER 2
INTERRUPT
T2EX PIN
EXF2
CONTROL
SU00067
EXEN2
Figure 4. Timer 2 in Auto-Reload Mode (DCEN = 0)
2000 Jan 20
11
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
(DOWN COUNTING RELOAD VALUE)
FFH
FFH
TOGGLE
EXF2
÷12
OSC
C/T2 = 0
OVERFLOW
TL2
T2 PIN
TH2
TF2
INTERRUPT
C/T2 = 1
CONTROL
TR2
COUNT
DIRECTION
1 = UP
0 = DOWN
RCAP2L
RCAP2H
(UP COUNTING RELOAD VALUE)
T2EX PIN
SU00730
Figure 5. Timer 2 Auto Reload Mode (DCEN = 1)
Timer 1
Overflow
÷2
NOTE: OSC. Freq. is divided by 2, not 12.
OSC
“0”
÷2
“1”
C/T2 = 0
SMOD
TL2
(8-bits)
“1”
TH2
(8-bits)
“0”
RCLK
C/T2 = 1
T2 Pin
Control
÷ 16
“1”
TR2
Reload
Transition
Detector
RCAP2L
T2EX Pin
EXF2
RCAP2H
RX Clock
“0”
TCLK
÷ 16
TX Clock
Timer 2
Interrupt
Control
EXEN2
Note availability of additional external interrupt.
Figure 6. Timer 2 in Baud Rate Generator Mode
2000 Jan 20
12
SU00068
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
under these conditions, a read or write of TH2 or TL2 may not be
accurate. The RCAP2 registers may be read, but should not be
written to, because a write might overlap a reload and cause write
and/or reload errors. The timer should be turned off (clear TR2)
before accessing the Timer 2 or RCAP2 registers.
Baud Rate Generator Mode
Bits TCLK and/or RCLK in T2CON (Table 3) allow the serial port
transmit and receive baud rates to be derived from either Timer 1 or
Timer 2. When TCLK= 0, Timer 1 is used as the serial port transmit
baud rate generator. When TCLK= 1, Timer 2 is used as the serial
port transmit baud rate generator. RCLK has the same effect for the
serial port receive baud rate. With these two bits, the serial port can
have different receive and transmit baud rates – one generated by
Timer 1, the other by Timer 2.
Table 4 shows commonly used baud rates and how they can be
obtained from Timer 2.
Table 4.
Figure 6 shows the Timer 2 in baud rate generation mode. The baud
rate generation mode is like the auto-reload mode, in that a rollover
in TH2 causes the Timer 2 registers to be reloaded with the 16-bit
value in registers RCAP2H and RCAP2L, which are preset by
software.
Timer 2
The baud rates in modes 1 and 3 are determined by Timer 2’s
overflow rate given below:
Modes 1 and 3 Baud Rates + Timer 2 Overflow Rate
16
The timer can be configured for either “timer” or “counter” operation.
In many applications, it is configured for “timer” operation (C/T2*=0).
Timer operation is different for Timer 2 when it is being used as a
baud rate generator.
Usually, as a timer it would increment every machine cycle (i.e., 1/12
the oscillator frequency). As a baud rate generator, it increments
every state time (i.e., 1/2 the oscillator frequency). Thus the baud
rate formula is as follows:
Ba d Rate
Baud
Osc Freq
375K
9.6K
2.8K
2.4K
1.2K
300
110
300
110
12MHz
12MHz
12MHz
12MHz
12MHz
12MHz
12MHz
6MHz
6MHz
RCAP2H
RCAP2L
FF
FF
FF
FF
FE
FB
F2
FD
F9
FF
D9
B2
64
C8
1E
AF
8F
57
Summary Of Baud Rate Equations
Timer 2 is in baud rate generating mode. If Timer 2 is being clocked
through pin T2(P1.0) the baud rate is:
Baud Rate + Timer 2 Overflow Rate
16
Modes 1 and 3 Baud Rates =
Oscillator Frequency
[32 [65536 * (RCAP2H, RCAP2L)]]
If Timer 2 is being clocked internally , the baud rate is:
Where: (RCAP2H, RCAP2L)= The content of RCAP2H and
RCAP2L taken as a 16-bit unsigned integer.
Baud Rate +
The Timer 2 as a baud rate generator mode shown in Figure 6, is
valid only if RCLK and/or TCLK = 1 in T2CON register. Note that a
rollover in TH2 does not set TF2, and will not generate an interrupt.
Thus, the Timer 2 interrupt does not have to be disabled when
Timer 2 is in the baud rate generator mode. Also if the EXEN2
(T2 external enable flag) is set, a 1-to-0 transition in T2EX
(Timer/counter 2 trigger input) will set EXF2 (T2 external flag) but
will not cause a reload from (RCAP2H, RCAP2L) to (TH2,TL2).
Therefore when Timer 2 is in use as a baud rate generator, T2EX
can be used as an additional external interrupt, if needed.
[32
f OSC
[65536 * (RCAP2H, RCAP2L)]]
Where fOSC= Oscillator Frequency
To obtain the reload value for RCAP2H and RCAP2L, the above
equation can be rewritten as:
RCAP2H, RCAP2L + 65536 *
ǒ
32
Ǔ
f OSC
Baud Rate
Timer/Counter 2 Set-up
Except for the baud rate generator mode, the values given for
T2CON do not include the setting of the TR2 bit. Therefore, bit TR2
must be set, separately, to turn the timer on. See Table 5 for set-up
of Timer 2 as a timer. Also see Table 6 for set-up of Timer 2 as a
counter.
When Timer 2 is in the baud rate generator mode, one should not try
to read or write TH2 and TL2. As a baud rate generator, Timer 2 is
incremented every state time (osc/2) or asynchronously from pin T2;
2000 Jan 20
Timer 2 Generated Commonly Used
Baud Rates
13
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
Table 5. Timer 2 as a Timer
MODE
T2CON
INTERNAL CONTROL (Note 1)
EXTERNAL CONTROL (Note 2)
16-bit Auto-Reload
00H
08H
16-bit Capture
01H
09H
Baud rate generator receive and transmit same baud rate
34H
36H
Receive only
24H
26H
Transmit only
14H
16H
Table 6. Timer 2 as a Counter
MODE
TMOD
INTERNAL CONTROL (Note 1)
EXTERNAL CONTROL (Note 2)
16-bit
02H
0AH
Auto-Reload
03H
0BH
NOTES:
1. Capture/reload occurs only on timer/counter overflow.
2. Capture/reload occurs on timer/counter overflow and a 1-to-0 transition on T2EX (P1.1) pin except when Timer 2 is used in the baud rate
generator mode.
SADDR are to b used and which bits are “don’t care”. The SADEN
mask can be logically ANDed with the SADDR to create the “Given”
address which the master will use for addressing each of the slaves.
Use of the Given address allows multiple slaves to be recognized
while excluding others. The following examples will help to show the
versatility of this scheme:
Enhanced UART
The UART operates in all of the usual modes that are described in
the first section of Data Handbook IC20, 80C51-Based 8-Bit
Microcontrollers. In addition the UART can perform framing error
detect by looking for missing stop bits, and automatic address
recognition. The 8XC51/31 UART also fully supports multiprocessor
communication.
When used for framing error detect the UART looks for missing stop
bits in the communication. A missing bit will set the FE bit in the
SCON register. The FE bit shares the SCON.7 bit with SM0 and the
function of SCON.7 is determined by PCON.6 (SMOD0) (see
Figure 7). If SMOD0 is set then SCON.7 functions as FE. SCON.7
functions as SM0 when SMOD0 is cleared. When used as FE
SCON.7 can only be cleared by software. Refer to Figure 8.
SADDR =
SADEN =
Given
=
1100 0000
1111 1101
1100 00X0
Slave 1
SADDR =
SADEN =
Given
=
1100 0000
1111 1110
1100 000X
In the above example SADDR is the same and the SADEN data is
used to differentiate between the two slaves. Slave 0 requires a 0 in
bit 0 and it ignores bit 1. Slave 1 requires a 0 in bit 1 and bit 0 is
ignored. A unique address for Slave 0 would be 1100 0010 since
slave 1 requires a 0 in bit 1. A unique address for slave 1 would be
1100 0001 since a 1 in bit 0 will exclude slave 0. Both slaves can be
selected at the same time by an address which has bit 0 = 0 (for
slave 0) and bit 1 = 0 (for slave 1). Thus, both could be addressed
with 1100 0000.
Automatic Address Recognition
Automatic Address Recognition is a feature which allows the UART
to recognize certain addresses in the serial bit stream by using
hardware to make the comparisons. This feature saves a great deal
of software overhead by eliminating the need for the software to
examine every serial address which passes by the serial port. This
feature is enabled by setting the SM2 bit in SCON. In the 9 bit UART
modes, mode 2 and mode 3, the Receive Interrupt flag (RI) will be
automatically set when the received byte contains either the “Given”
address or the “Broadcast” address. The 9 bit mode requires that
the 9th information bit is a 1 to indicate that the received information
is an address and not data. Automatic address recognition is shown
in Figure 9.
In a more complex system the following could be used to select
slaves 1 and 2 while excluding slave 0:
The 8 bit mode is called Mode 1. In this mode the RI flag will be set
if SM2 is enabled and the information received has a valid stop bit
following the 8 address bits and the information is either a Given or
Broadcast address.
Mode 0 is the Shift Register mode and SM2 is ignored.
Using the Automatic Address Recognition feature allows a master to
selectively communicate with one or more slaves by invoking the
Given slave address or addresses. All of the slaves may be
contacted by using the Broadcast address. Two special Function
Registers are used to define the slave’s address, SADDR, and the
address mask, SADEN. SADEN is used to define which bits in the
2000 Jan 20
Slave 0
Slave 0
SADDR =
SADEN =
Given
=
1100 0000
1111 1001
1100 0XX0
Slave 1
SADDR =
SADEN =
Given
=
1110 0000
1111 1010
1110 0X0X
Slave 2
SADDR =
SADEN =
Given
=
1110 0000
1111 1100
1110 00XX
In the above example the differentiation among the 3 slaves is in the
lower 3 address bits. Slave 0 requires that bit 0 = 0 and it can be
uniquely addressed by 1110 0110. Slave 1 requires that bit 1 = 0 and
it can be uniquely addressed by 1110 and 0101. Slave 2 requires
that bit 2 = 0 and its unique address is 1110 0011. To select Slaves 0
14
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
and 1 and exclude Slave 2 use address 1110 0100, since it is
necessary to make bit 2 = 1 to exclude slave 2.
Upon reset SADDR (SFR address 0A9H) and SADEN (SFR
address 0B9H) are leaded with 0s. This produces a given address
of all “don’t cares” as well as a Broadcast address of all “don’t
cares”. This effectively disables the Automatic Addressing mode and
allows the microcontroller to use standard 80C51 type UART drivers
which do not make use of this feature.
The Broadcast Address for each slave is created by taking the
logical OR of SADDR and SADEN. Zeros in this result are trended
as don’t-cares. In most cases, interpreting the don’t-cares as ones,
the broadcast address will be FF hexadecimal.
SCON Address = 98H
Reset Value = 0000 0000B
Bit Addressable
SM0/FE
Bit:
SM1
7
6
(SMOD0 = 0/1)*
SM2
REN
TB8
RB8
Tl
Rl
5
4
3
2
1
0
Symbol
Function
FE
Framing Error bit. This bit is set by the receiver when an invalid stop bit is detected. The FE bit is not cleared by valid
frames but should be cleared by software. The SMOD0 bit must be set to enable access to the FE bit.
SM0
Serial Port Mode Bit 0, (SMOD0 must = 0 to access bit SM0)
SM1
Serial Port Mode Bit 1
SM0
SM1
Mode
0
0
1
1
0
1
0
1
0
1
2
3
Description
Baud Rate**
shift register
8-bit UART
9-bit UART
9-bit UART
fOSC/12
variable
fOSC/64 or fOSC/32
variable
SM2
Enables the Automatic Address Recognition feature in Modes 2 or 3. If SM2 = 1 then Rl will not be set unless the
received 9th data bit (RB8) is 1, indicating an address, and the received byte is a Given or Broadcast Address.
In Mode 1, if SM2 = 1 then Rl will not be activated unless a valid stop bit was received, and the received byte is a
Given or Broadcast Address. In Mode 0, SM2 should be 0.
REN
Enables serial reception. Set by software to enable reception. Clear by software to disable reception.
TB8
The 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software as desired.
RB8
In modes 2 and 3, the 9th data bit that was received. In Mode 1, if SM2 = 0, RB8 is the stop bit that was received.
In Mode 0, RB8 is not used.
Tl
Transmit interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or at the beginning of the stop bit in the
other modes, in any serial transmission. Must be cleared by software.
Rl
Receive interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or halfway through the stop bit time in
the other modes, in any serial reception (except see SM2). Must be cleared by software.
NOTE:
*SMOD0 is located at PCON6.
**fOSC = oscillator frequency
SU00043
Figure 7. SCON: Serial Port Control Register
2000 Jan 20
15
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
D0
D1
D2
D3
D4
D5
D6
D7
D8
DATA BYTE
START
BIT
ONLY IN
MODE 2, 3
STOP
BIT
SET FE BIT IF STOP BIT IS 0 (FRAMING ERROR)
SM0 TO UART MODE CONTROL
SM0 / FE
SM1
SM2
REN
SMOD1
SMOD0
–
POF
TB8
GF1
RB8
TI
GF0
PD
RI
SCON
(98H)
IDL
PCON
(87H)
0 : SCON.7 = SM0
1 : SCON.7 = FE
SU01191
Figure 8. UART Framing Error Detection
D0
D1
D2
D3
D4
SM0
SM1
1
1
1
0
D5
SM2
1
D6
D7
D8
REN
TB8
RB8
1
X
TI
RI
SCON
(98H)
RECEIVED ADDRESS D0 TO D7
COMPARATOR
PROGRAMMED ADDRESS
IN UART MODE 2 OR MODE 3 AND SM2 = 1:
INTERRUPT IF REN=1, RB8=1 AND “RECEIVED ADDRESS” = “PROGRAMMED ADDRESS”
– WHEN OWN ADDRESS RECEIVED, CLEAR SM2 TO RECEIVE DATA BYTES
– WHEN ALL DATA BYTES HAVE BEEN RECEIVED: SET SM2 TO WAIT FOR NEXT ADDRESS.
SU00045
Figure 9. UART Multiprocessor Communication, Automatic Address Recognition
2000 Jan 20
16
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
An interrupt will be serviced as long as an interrupt of equal or
higher priority is not already being serviced. If an interrupt of equal
or higher level priority is being serviced, the new interrupt will wait
until it is finished before being serviced. If a lower priority level
interrupt is being serviced, it will be stopped and the new interrupt
serviced. When the new interrupt is finished, the lower priority level
interrupt that was stopped will be completed.
Interrupt Priority Structure
The 8XC51 and 80C31 only have a 6-source four-level interrupt
structure. They are the IE, IP and IPH. (See Figures 10, 11, and 12.)
The IPH (Interrupt Priority High) register that makes the four-level
interrupt structure possible. The IPH is located at SFR address B7H.
The structure of the IPH register and a description of its bits is
shown in Figure 12.
The function of the IPH SFR is simple and when combined with the
IP SFR determines the priority of each interrupt. The priority of each
interrupt is determined as shown in the following table:
PRIORITY BITS
INTERRUPT PRIORITY LEVEL
IPH.x
IP.x
0
0
Level 0 (lowest priority)
0
1
Level 1
1
0
Level 2
1
1
Level 3 (highest priority)
Table 7.
Interrupt Table
SOURCE
POLLING PRIORITY
REQUEST BITS
HARDWARE CLEAR?
N
(L)1
Y
(T)2
VECTOR ADDRESS
X0
1
IE0
T0
2
TP0
Y
03H
X1
3
IE1
N (L) Y (T)
13H
T1
4
TF1
Y
1BH
SP
5
RI, TI
N
23H
T2
6
TF2, EXF2
N
2BH
0BH
NOTES:
1. L = Level activated
2. T = Transition activated
IE (0A8H)
7
6
5
4
3
2
1
0
EA
—
ET2
ES
ET1
EX1
ET0
EX0
Enable Bit = 1 enables the interrupt.
Enable Bit = 0 disables it.
BIT
IE.7
SYMBOL
EA
IE.6
IE.5
IE.4
IE.3
IE.2
IE.1
IE.0
—
ET2
ES
ET1
EX1
ET0
EX0
FUNCTION
Global disable bit. If EA = 0, all interrupts are disabled. If EA = 1, each interrupt can be individually
enabled or disabled by setting or clearing its enable bit.
Not implemented. Reserved for future use.
Timer 2 interrupt enable bit.
Serial Port interrupt enable bit.
Timer 1 interrupt enable bit.
External interrupt 1 enable bit.
Timer 0 interrupt enable bit.
External interrupt 0 enable bit.
SU00571
Figure 10. IE Registers
2000 Jan 20
17
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
IP (0B8H)
7
6
5
4
3
2
1
0
—
—
PT2
PS
PT1
PX1
PT0
PX0
Priority Bit = 1 assigns higher priority
Priority Bit = 0 assigns lower priority
BIT
IP.7
IP.6
IP.5
IP.4
IP.3
IP.2
IP.1
IP.0
SYMBOL
—
—
PT2
PS
PT1
PX1
PT0
PX0
FUNCTION
Not implemented, reserved for future use.
Not implemented, reserved for future use.
Timer 2 interrupt priority bit.
Serial Port interrupt priority bit.
Timer 1 interrupt priority bit.
External interrupt 1 priority bit.
Timer 0 interrupt priority bit.
External interrupt 0 priority bit.
SU00572
Figure 11. IP Registers
IPH (B7H)
7
6
5
4
3
2
1
0
—
—
PT2H
PSH
PT1H
PX1H
PT0H
PX0H
Priority Bit = 1 assigns higher priority
Priority Bit = 0 assigns lower priority
BIT
IPH.7
IPH.6
IPH.5
IPH.4
IPH.3
IPH.2
IPH.1
IPH.0
SYMBOL
—
—
PT2H
PSH
PT1H
PX1H
PT0H
PX0H
FUNCTION
Not implemented, reserved for future use.
Not implemented, reserved for future use.
Timer 2 interrupt priority bit high.
Serial Port interrupt priority bit high.
Timer 1 interrupt priority bit high.
External interrupt 1 priority bit high.
Timer 0 interrupt priority bit high.
External interrupt 0 priority bit high.
Figure 12. IPH Registers
2000 Jan 20
18
SU01058
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
Note that bit 2 is not writable and is always read as a zero. This
allows the DPS bit to be quickly toggled simply by executing an INC
DPTR insstruction without affecting the WOPD or LPEP bits.
Reduced EMI Mode
The AO bit (AUXR.0) in the AUXR register when set disables the
ALE output.
Reduced EMI Mode
AUXR (8EH)
DPS
7
6
5
4
3
2
1
0
–
–
–
–
–
–
–
AO
AUXR.0
AO
BIT0
AUXR1
DPTR1
DPTR0
Turns off ALE output.
DPH
(83H)
DPL
(82H)
EXTERNAL
DATA
MEMORY
Dual DPTR
SU00745A
The dual DPTR structure (see Figure 13) enables a way to specify
the address of an external data memory location. There are two
16-bit DPTR registers that address the external memory, and a
single bit called DPS = AUXR1/bit0 that allows the program code to
switch between them.
Figure 13.
DPTR Instructions
The instructions that refer to DPTR refer to the data pointer that is
currently selected using the AUXR1/bit 0 register. The six
instructions that use the DPTR are as follows:
• New Register Name: AUXR1#
• SFR Address: A2H
• Reset Value: xxx000x0B
INC DPTR
AUXR1 (A2H)
7
6
5
4
3
2
1
0
–
–
–
LPEP
WUPD
0
–
DPS
Where:
DPS = AUXR1/bit0 = Switches between DPTR0 and DPTR1.
Select Reg
DPS
DPTR0
0
DPTR1
1
MOV DPTR, #data16
Loads the DPTR with a 16-bit constant
MOV A, @ A+DPTR
Move code byte relative to DPTR to ACC
MOVX A, @ DPTR
Move external RAM (16-bit address) to
ACC
MOVX @ DPTR , A
Move ACC to external RAM (16-bit
address)
JMP @ A + DPTR
Jump indirect relative to DPTR
The data pointer can be accessed on a byte-by-byte basis by
specifying the low or high byte in an instruction which accesses the
SFRs. See application note AN458 for more details.
The DPS bit status should be saved by software when switching
between DPTR0 and DPTR1.
2000 Jan 20
Increments the data pointer by 1
19
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
ABSOLUTE MAXIMUM RATINGS1, 2, 3
PARAMETER
Operating temperature under bias
Storage temperature range
RATING
UNIT
0 to +70 or –40 to +85
°C
–65 to +150
°C
0 to +13.0
V
Voltage on EA/VPP pin to VSS
Voltage on any other pin to VSS
–0.5 to +6.5
V
15
mA
Maximum IOL per I/O pin
Power dissipation (based on package heat transfer limitations, not device power consumption)
1.5
W
NOTES:
1. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and
functional operation of the device at these or any conditions other than those described in the AC and DC Electrical Characteristics section
of this specification is not implied.
2. This product includes circuitry specifically designed for the protection of its internal devices from the damaging effects of excessive static
charge. Nonetheless, it is suggested that conventional precautions be taken to avoid applying greater than the rated maximum.
3. Parameters are valid over operating temperature range unless otherwise specified. All voltages are with respect to VSS unless otherwise
noted.
AC ELECTRICAL CHARACTERISTICS
Tamb = 0°C to +70°C or –40°C to +85°C
CLOCK FREQUENCY
RANGE –f
SYMBOL
1/tCLCL
2000 Jan 20
FIGURE
29
PARAMETER
Oscillator frequency
Speed versions : S (16MHz)
U (33MHz)
20
MIN
MAX
0
0
16
33
UNIT
MHz
MHz
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
DC ELECTRICAL CHARACTERISTICS
Tamb = 0°C to +70°C or –40°C to +85°C, VCC = 2.7V to 5.5V, VSS = 0V (16MHz devices)
SYMBOL
VIL
Input low voltage
VIH
Input high voltage (ports 0, 1, 2, 3, EA)
VIH1
Input high voltage, XTAL1, RST
MIN
4.0V < VCC < 5.5V
–0.5
2.7V<VCC< 4.0V
VOL
Output low voltage, ports 1, 2, 8
VCC = 2.7V
IOL = 1.6mA2
VOL1
Output low voltage, port 0, ALE, PSEN8, 7
VCC = 2.7V
IOL = 3.2mA2
VOH
O
voltage ports 1,
1 2,
2 3
Output high voltage,
LIMITS
TEST
CONDITIONS
PARAMETER
3
TYP1
MAX
UNIT
0.2VCC–0.1
V
–0.5
0.7
V
0.2VCC+0.9
VCC+0.5
V
0.7VCC
VCC+0.5
V
0.4
V
0.4
V
VCC = 2.7V
IOH = –20µA
VCC – 0.7
V
VCC = 4.5V
IOH = –30µA
VCC – 0.7
V
VCC = 2.7V
IOH = –3.2mA
VCC – 0.7
V
–1
VOH1
Output high voltage (port 0 in external bus mode),
ALE9, PSEN3
IIL
Logical 0 input current, ports 1, 2, 3
VIN = 0.4V
–50
µA
ITL
Logical 1-to-0 transition current, ports 1, 2, 36
VIN = 2.0V
See note 4
–650
µA
ILI
Input leakage current, port 0
0.45 < VIN < VCC – 0.3
±10
µA
ICC
Power supply current (see Figure 21):
Active mode @ 16MHz
Idle mode @ 16MHz
Power-down mode or clock stopped (see Figure 25
for
f conditions)
diti
)
50
75
µA
µA
µA
µA
225
kΩ
RRST
See note 5
Tamb = 0°C to 70°C
Tamb = –40°C to +85°C
Internal reset pull-down resistor
3
40
CIO
Pin capacitance10 (except EA)
15
pF
NOTES:
1. Typical ratings are not guaranteed. The values listed are at room temperature, 5V.
2. Capacitive loading on ports 0 and 2 may cause spurious noise to be superimposed on the VOLs of ALE and ports 1 and 3. The noise is due
to external bus capacitance discharging into the port 0 and port 2 pins when these pins make 1-to-0 transitions during bus operations. In the
worst cases (capacitive loading > 100pF), the noise pulse on the ALE pin may exceed 0.8V. In such cases, it may be desirable to qualify
ALE with a Schmitt Trigger, or use an address latch with a Schmitt Trigger STROBE input. IOL can exceed these conditions provided that no
single output sinks more than 5mA and no more than two outputs exceed the test conditions.
3. Capacitive loading on ports 0 and 2 may cause the VOH on ALE and PSEN to momentarily fall below the VCC–0.7 specification when the
address bits are stabilizing.
4. Pins of ports 1, 2 and 3 source a transition current when they are being externally driven from 1 to 0. The transition current reaches its
maximum value when VIN is approximately 2V.
5. See Figures 22 through 25 for ICC test conditions.
Active mode:
ICC = 0.9 × FREQ. + 1.1mA
Idle mode:
ICC = 0.18 × FREQ. +1.01mA; See Figure 21.
6. This value applies to Tamb = 0°C to +70°C. For Tamb = –40°C to +85°C, ITL = –750µA.
7. Load capacitance for port 0, ALE, and PSEN = 100pF, load capacitance for all other outputs = 80pF.
8. Under steady state (non-transient) conditions, IOL must be externally limited as follows:
Maximum IOL per port pin:
15mA (*NOTE: This is 85°C specification.)
26mA
Maximum IOL per 8-bit port:
Maximum total IOL for all outputs:
71mA
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed
test conditions.
9. ALE is tested to VOH1, except when ALE is off then VOH is the voltage specification.
10. Pin capacitance is characterized but not tested. Pin capacitance is less than 25pF. Pin capacitance of ceramic package is less than 15pF
(except EA is 25pF).
2000 Jan 20
21
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
DC ELECTRICAL CHARACTERISTICS
Tamb = 0°C to +70°C or –40°C to +85°C, 33MHz devices; 5V ±10%; VSS = 0V
SYMBOL
TEST
CONDITIONS
PARAMETER
VIL
Input low voltage
VIH
Input high voltage (ports 0, 1, 2, 3, EA)
VIH1
Input high voltage, XTAL1, RST
VOL
Output low voltage, ports 1, 2, 3 8
VOL1
MIN
TYP1
UNIT
MAX
–0.5
0.2VCC–0.1
V
0.2VCC+0.9
VCC+0.5
V
0.7VCC
VCC+0.5
V
VCC = 4.5V
IOL = 1.6mA2
0.4
V
Output low voltage, port 0, ALE, PSEN 7, 8
VCC = 4.5V
IOL = 3.2mA2
0.4
V
VOH
Output high voltage, ports 1, 2, 3 3
VCC = 4.5V
IOH = –30µA
VCC – 0.7
V
VOH1
Output high voltage (port 0 in external bus mode),
ALE9, PSEN3
VCC = 4.5V
IOH = –3.2mA
VCC – 0.7
V
IIL
Logical 0 input current, ports 1, 2, 3
VIN = 0.4V
–1
ITL
Logical 1-to-0 transition current, ports 1, 2, 36
ILI
Input leakage current, port 0
ICC
Power supply current (see Figure 21):
Active mode (see Note 5)
Idle mode (see Note 5)
Power-down mode or clock stopped (see Figure 25
for
f conditions)
diti
)
RRST
CIO
4.5V < VCC < 5.5V
LIMITS
–50
µA
VIN = 2.0V
See note 4
–650
µA
0.45 < VIN < VCC – 0.3
±10
µA
50
75
µA
µA
225
kΩ
15
pF
See note 5
Tamb = 0°C to 70°C
Tamb = –40°C to +85°C
Internal reset pull-down resistor
Pin
capacitance10
3
40
(except EA)
NOTES:
1. Typical ratings are not guaranteed. The values listed are at room temperature, 5V.
2. Capacitive loading on ports 0 and 2 may cause spurious noise to be superimposed on the VOLs of ALE and ports 1 and 3. The noise is due
to external bus capacitance discharging into the port 0 and port 2 pins when these pins make 1-to-0 transitions during bus operations. In the
worst cases (capacitive loading > 100pF), the noise pulse on the ALE pin may exceed 0.8V. In such cases, it may be desirable to qualify
ALE with a Schmitt Trigger, or use an address latch with a Schmitt Trigger STROBE input. IOL can exceed these conditions provided that no
single output sinks more than 5mA and no more than two outputs exceed the test conditions.
3. Capacitive loading on ports 0 and 2 may cause the VOH on ALE and PSEN to momentarily fall below the VCC–0.7 specification when the
address bits are stabilizing.
4. Pins of ports 1, 2 and 3 source a transition current when they are being externally driven from 1 to 0. The transition current reaches its
maximum value when VIN is approximately 2V.
5. See Figures 22 through 25 for ICC test conditions.
Active mode:
ICC(MAX) = 0.9 × FREQ. + 1.1mA
Idle mode:
ICC(MAX) = 0.18 × FREQ. +1.0mA; See Figure 21.
6. This value applies to Tamb = 0°C to +70°C. For Tamb = –40°C to +85°C, ITL = –750µA.
7. Load capacitance for port 0, ALE, and PSEN = 100pF, load capacitance for all other outputs = 80pF.
8. Under steady state (non-transient) conditions, IOL must be externally limited as follows:
15mA (*NOTE: This is 85°C specification.)
Maximum IOL per port pin:
Maximum IOL per 8-bit port:
26mA
71mA
Maximum total IOL for all outputs:
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed
test conditions.
9. ALE is tested to VOH1, except when ALE is off then VOH is the voltage specification.
10. Pin capacitance is characterized but not tested. Pin capacitance is less than 25pF. Pin capacitance of ceramic package is less than 15pF
(except EA is 25pF).
2000 Jan 20
22
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
AC ELECTRICAL CHARACTERISTICS
Tamb = 0°C to +70°C or –40°C to +85°C, VCC = +2.7V to +5.5V, VSS = 0V1, 2, 3
16MHz CLOCK
SYMBOL
FIGURE
PARAMETER
MIN
MAX
Oscillator frequency5
Speed versions :S
VARIABLE CLOCK
MIN
MAX
UNIT
3.5
16
MHz
1/tCLCL
14
tLHLL
14
ALE pulse width
85
2tCLCL–40
ns
tAVLL
14
Address valid to ALE low
22
tCLCL–40
ns
tLLAX
14
Address hold after ALE low
32
tLLIV
14
ALE low to valid instruction in
tLLPL
14
ALE low to PSEN low
32
tPLPH
14
PSEN pulse width
142
tPLIV
14
PSEN low to valid instruction in
tPXIX
14
Input instruction hold after PSEN
tPXIZ
14
Input instruction float after PSEN
37
tCLCL–25
ns
14
Address to valid instruction in
207
5tCLCL–105
ns
14
PSEN low to address float
10
10
ns
tAVIV
4
tPLAZ
tCLCL–30
150
ns
4tCLCL–100
tCLCL–30
ns
3tCLCL–45
82
0
ns
ns
3tCLCL–105
0
ns
ns
Data Memory
tRLRH
15, 16
RD pulse width
275
6tCLCL–100
ns
tWLWH
15, 16
WR pulse width
275
6tCLCL–100
ns
tRLDV
15, 16
RD low to valid data in
tRHDX
15, 16
Data hold after RD
tRHDZ
15, 16
Data float after RD
65
2tCLCL–60
ns
tLLDV
15, 16
ALE low to valid data in
350
8tCLCL–150
ns
tAVDV
15, 16
Address to valid data in
397
9tCLCL–165
ns
tLLWL
15, 16
ALE low to RD or WR low
137
3tCLCL+50
ns
tAVWL
15, 16
Address valid to WR low or RD low
122
4tCLCL–130
ns
tQVWX
15, 16
Data valid to WR transition
13
tCLCL–50
ns
tWHQX
15, 16
Data hold after WR
13
tCLCL–50
ns
tQVWH
16
Data valid to WR high
287
7tCLCL–150
ns
tRLAZ
15, 16
RD low to address float
tWHLH
15, 16
RD or WR high to ALE high
23
147
0
5tCLCL–165
0
239
3tCLCL–50
0
103
tCLCL–40
ns
ns
0
ns
tCLCL+40
ns
External Clock
tCHCX
18
High time
20
20
tCLCL–tCLCX
ns
tCLCX
18
Low time
20
20
tCLCL–tCHCX
ns
tCLCH
18
Rise time
20
20
ns
tCHCL
18
Fall time
20
20
ns
tXLXL
17
Serial port clock cycle time
750
12tCLCL
ns
tQVXH
17
Output data setup to clock rising edge
492
10tCLCL–133
ns
tXHQX
17
Output data hold after clock rising edge
8
2tCLCL–117
ns
tXHDX
17
Input data hold after clock rising edge
0
0
ns
Shift Register
tXHDV
17
Clock rising edge to input data valid
492
10tCLCL–133
ns
NOTES:
1. Parameters are valid over operating temperature range unless otherwise specified.
2. Load capacitance for port 0, ALE, and PSEN = 100pF, load capacitance for all other outputs = 80pF.
3. Interfacing the 8XC51 and 80C31 to devices with float times up to 45ns is permitted. This limited bus contention will not cause damage to
Port 0 drivers.
4. See application note AN457 for external memory interface.
5. Parts are guaranteed to operate down to 0Hz.
2000 Jan 20
23
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
AC ELECTRICAL CHARACTERISTICS
Tamb = 0°C to +70°C or –40°C to +85°C, VCC = 5V ±10%, VSS = 0V1, 2, 3
VARIABLE CLOCK4
33MHz CLOCK
16MHz to fmax
SYMBOL
FIGURE
PARAMETER
MIN
MAX
MIN
MAX
UNIT
tLHLL
14
ALE pulse width
2tCLCL–40
21
ns
tAVLL
14
Address valid to ALE low
tCLCL–25
5
ns
tLLAX
14
Address hold after ALE low
tCLCL–25
tLLIV
14
ALE low to valid instruction in
tLLPL
14
ALE low to PSEN low
tCLCL–25
5
ns
tPLPH
14
PSEN pulse width
3tCLCL–45
45
ns
tPLIV
14
PSEN low to valid instruction in
tPXIX
14
Input instruction hold after PSEN
tPXIZ
14
Input instruction float after PSEN
tCLCL–25
5
ns
tAVIV
14
Address to valid instruction in
5tCLCL–80
70
ns
tPLAZ
14
PSEN low to address float
10
10
ns
ns
4tCLCL–65
55
3tCLCL–60
0
30
0
ns
ns
ns
Data Memory
tRLRH
15, 16
RD pulse width
6tCLCL–100
82
tWLWH
15, 16
WR pulse width
6tCLCL–100
82
tRLDV
15, 16
RD low to valid data in
tRHDX
15, 16
Data hold after RD
tRHDZ
15, 16
Data float after RD
2tCLCL–28
32
ns
tLLDV
15, 16
ALE low to valid data in
8tCLCL–150
90
ns
tAVDV
15, 16
Address to valid data in
9tCLCL–165
105
ns
tLLWL
15, 16
ALE low to RD or WR low
3tCLCL–50
140
ns
tAVWL
15, 16
Address valid to WR low or RD low
4tCLCL–75
45
ns
tQVWX
15, 16
Data valid to WR transition
tCLCL–30
0
ns
tWHQX
15, 16
Data hold after WR
tCLCL–25
5
ns
tQVWH
16
7tCLCL–130
80
tRLAZ
15, 16
RD low to address float
tWHLH
15, 16
RD or WR high to ALE high
tCLCL–25
5tCLCL–90
0
Data valid to WR high
ns
ns
60
0
3tCLCL+50
40
0
tCLCL+25
5
ns
ns
ns
0
ns
55
ns
External Clock
tCHCX
18
High time
0.38tCLCL
tCLCL–tCLCX
ns
tCLCX
18
Low time
0.38tCLCL
tCLCL–tCHCX
ns
tCLCH
18
Rise time
5
ns
tCHCL
18
Fall time
5
ns
tXLXL
17
Serial port clock cycle time
12tCLCL
360
ns
tQVXH
17
Output data setup to clock rising edge
10tCLCL–133
167
ns
tXHQX
17
Output data hold after clock rising edge
2tCLCL–80
tXHDX
17
Input data hold after clock rising edge
Shift Register
0
ns
0
ns
tXHDV
17
Clock rising edge to input data valid
10tCLCL–133
167
ns
NOTES:
1. Parameters are valid over operating temperature range unless otherwise specified.
2. Load capacitance for port 0, ALE, and PSEN = 100pF, load capacitance for all other outputs = 80pF.
3. Interfacing the 8XC51 and 80C31 to devices with float times up to 45ns is permitted. This limited bus contention will not cause damage to
Port 0 drivers.
4. Variable clock is specified for oscillator frequencies greater than 16MHz to 33MHz. For frequencies equal or less than 16MHz, see 16MHz
“AC Electrical Characteristics”, page 23.
5. Parts are guaranteed to operate down to 0Hz.
2000 Jan 20
24
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
EXPLANATION OF THE AC SYMBOLS
P – PSEN
Q – Output data
R – RD signal
t – Time
V – Valid
W – WR signal
X – No longer a valid logic level
Z – Float
Examples: tAVLL = Time for address valid to ALE low.
tLLPL =Time for ALE low to PSEN low.
Each timing symbol has five characters. The first character is always
‘t’ (= time). The other characters, depending on their positions,
indicate the name of a signal or the logical status of that signal. The
designations are:
A – Address
C – Clock
D – Input data
H – Logic level high
I – Instruction (program memory contents)
L – Logic level low, or ALE
tLHLL
ALE
tAVLL
tLLPL
tPLPH
tLLIV
tPLIV
PSEN
tLLAX
INSTR IN
A0–A7
PORT 0
tPXIZ
tPLAZ
tPXIX
A0–A7
tAVIV
PORT 2
A0–A15
A8–A15
SU00006
Figure 14. External Program Memory Read Cycle
ALE
tWHLH
PSEN
tLLDV
tLLWL
tRLRH
RD
tAVLL
tLLAX
tRLAZ
PORT 0
tRHDZ
tRLDV
tRHDX
A0–A7
FROM RI OR DPL
DATA IN
A0–A7 FROM PCL
INSTR IN
tAVWL
tAVDV
PORT 2
P2.0–P2.7 OR A8–A15 FROM DPF
A0–A15 FROM PCH
SU00025
Figure 15. External Data Memory Read Cycle
2000 Jan 20
25
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
ALE
tWHLH
PSEN
tWLWH
tLLWL
WR
tLLAX
tAVLL
tWHQX
tQVWX
tQVWH
A0–A7
FROM RI OR DPL
PORT 0
DATA OUT
A0–A7 FROM PCL
INSTR IN
tAVWL
PORT 2
P2.0–P2.7 OR A8–A15 FROM DPF
A0–A15 FROM PCH
SU00026
Figure 16. External Data Memory Write Cycle
INSTRUCTION
0
1
2
3
4
5
6
7
8
ALE
tXLXL
CLOCK
tXHQX
tQVXH
OUTPUT DATA
0
1
2
WRITE TO SBUF
3
4
5
6
7
tXHDX
tXHDV
SET TI
INPUT DATA
VALID
VALID
VALID
VALID
VALID
VALID
VALID
VALID
CLEAR RI
SET RI
SU00027
Figure 17. Shift Register Mode Timing
VCC–0.5
0.45V
0.7VCC
0.2VCC–0.1
tCHCL
tCHCX
tCLCH
tCLCX
tCLCL
SU00009
Figure 18. External Clock Drive
2000 Jan 20
26
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
VCC–0.5
VLOAD+0.1V
0.2VCC+0.9
TIMING
REFERENCE
POINTS
VLOAD
0.45V
0.2VCC–0.1
VLOAD–0.1V
SU00717
SU00718
Figure 19. AC Testing Input/Output
Figure 20. Float Waveform
35
30
ICC(mA)
25
MAX ACTIVE
MODE (EXCEPT
8XC51RD+)
ICCMAX ACTIVE MODE
(8XC51RD+)
ICCMAX = 0.9 X FREQ + 2.1
15
ICCMAX = 0.9 X
FREQ. + 1.1
TYP ACTIVE MODE
10
MAX IDLE MODE
5
TYP IDLE MODE
4
8
12
16
20
24
28
32
36
FREQ AT XTAL1 (MHz)
SU00837A
Figure 21. ICC vs. FREQ
Valid only within frequency specifications of the device under test
2000 Jan 20
VOL+0.1V
NOTE:
For timing purposes, a port is no longer floating when a 100mV change from
load voltage occurs, and begins to float when a 100mV change from the loaded
VOH/VOL level occurs. IOH/IOL ≥ ±20mA.
NOTE:
AC inputs during testing are driven at VCC –0.5 for a logic ‘1’ and 0.45V for a logic ‘0’.
Timing measurements are made at VIH min for a logic ‘1’ and VIL max for a logic ‘0’.
20
VOH–0.1V
27
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
VCC
VCC
ICC
ICC
VCC
VCC
VCC
VCC
RST
RST
P0
P0
EA
EA
(NC)
XTAL2
(NC)
XTAL2
CLOCK SIGNAL
XTAL1
CLOCK SIGNAL
XTAL1
VSS
VSS
SU00719
SU00720
Figure 22. ICC Test Condition, Active Mode
All other pins are disconnected
VCC–0.5
Figure 23. ICC Test Condition, Idle Mode
All other pins are disconnected
0.7VCC
0.2VCC–0.1
0.45V
tCHCL
tCHCX
tCLCH
tCLCX
tCLCL
SU00009
Figure 24. Clock Signal Waveform for ICC Tests in Active and Idle Modes
tCLCH = tCHCL = 5ns
VCC
ICC
VCC
VCC
RST
P0
EA
(NC)
XTAL2
XTAL1
VSS
SU00016
Figure 25. ICC Test Condition, Power Down Mode
All other pins are disconnected. VCC = 2V to 5.5V
2000 Jan 20
VCC
28
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
If the 64 byte encryption table has been programmed, the data
presented at port 0 will be the exclusive NOR of the program byte
with one of the encryption bytes. The user will have to know the
encryption table contents in order to correctly decode the verification
data. The encryption table itself cannot be read out.
EPROM CHARACTERISTICS
All these devices can be programmed by using a modified Improved
Quick-Pulse Programming algorithm. It differs from older methods
in the value used for VPP (programming supply voltage) and in the
width and number of the ALE/PROG pulses.
Reading the Signature Bytes
The signature bytes are read by the same procedure as a normal
verification of locations 030H and 031H, except that P3.6 and P3.7
need to be pulled to a logic low. The values are:
(030H) = 15H indicates manufactured by Philips
(031H) = 92H indicates 87C51
The family contains two signature bytes that can be read and used
by an EPROM programming system to identify the device. The
signature bytes identify the device as being manufactured by
Philips.
Table 8 shows the logic levels for reading the signature byte, and for
programming the program memory, the encryption table, and the
security bits. The circuit configuration and waveforms for quick-pulse
programming are shown in Figures 26 and 27. Figure 28 shows the
circuit configuration for normal program memory verification.
Program/Verify Algorithms
Quick-Pulse Programming
Erasure Characteristics
The setup for microcontroller quick-pulse programming is shown in
Figure 26. Note that the device is running with a 4 to 6MHz
oscillator. The reason the oscillator needs to be running is that the
device is executing internal address and program data transfers.
Erasure of the EPROM begins to occur when the chip is exposed to
light with wavelengths shorter than approximately 4,000 angstroms.
Since sunlight and fluorescent lighting have wavelengths in this
range, exposure to these light sources over an extended time (about
1 week in sunlight, or 3 years in room level fluorescent lighting)
could cause inadvertent erasure. For this and secondary effects,
it is recommended that an opaque label be placed over the
window. For elevated temperature or environments where solvents
are being used, apply Kapton tape Fluorglas part number 2345–5, or
equivalent.
Any algorithm in agreement with the conditions listed in Table 8, and
which satisfies the timing specifications, is suitable.
The address of the EPROM location to be programmed is applied to
ports 1 and 2, as shown in Figure 26. The code byte to be
programmed into that location is applied to port 0. RST, PSEN and
pins of ports 2 and 3 specified in Table 8 are held at the ‘Program
Code Data’ levels indicated in Table 8. The ALE/PROG is pulsed
low 5 times as shown in Figure 27.
The recommended erasure procedure is exposure to ultraviolet light
(at 2537 angstroms) to an integrated dose of at least 15W-s/cm2.
Exposing the EPROM to an ultraviolet lamp of 12,000µW/cm2 rating
for 20 to 39 minutes, at a distance of about 1 inch, should be
sufficient.
To program the encryption table, repeat the 5 pulse programming
sequence for addresses 0 through 1FH, using the ‘Pgm Encryption
Table’ levels. Do not forget that after the encryption table is
programmed, verification cycles will produce only encrypted data.
To program the security bits, repeat the 5 pulse programming
sequence using the ‘Pgm Security Bit’ levels. After one security bit is
programmed, further programming of the code memory and
encryption table is disabled. However, the other security bits can still
be programmed.
Erasure leaves the array in an all 1s state.
Security Bits
With none of the security bits programmed the code in the program
memory can be verified. If the encryption table is programmed, the
code will be encrypted when verified. When only security bit 1 (see
Table 9) is programmed, MOVC instructions executed from external
program memory are disabled from fetching code bytes from the
internal memory, EA is latched on Reset and all further programming
of the EPROM is disabled. When security bits 1 and 2 are
programmed, in addition to the above, verify mode is disabled.
When all three security bits are programmed, all of the conditions
above apply and all external program memory execution is disabled.
Note that the EA/VPP pin must not be allowed to go above the
maximum specified VPP level for any amount of time. Even a narrow
glitch above that voltage can cause permanent damage to the
device. The VPP source should be well regulated and free of glitches
and overshoot.
Program Verification
If security bits 2 and 3 have not been programmed, the on-chip
program memory can be read out for program verification. The
address of the program memory locations to be read is applied to
ports 1 and 2 as shown in Figure 28. The other pins are held at the
‘Verify Code Data’ levels indicated in Table 8. The contents of the
address location will be emitted on port 0. External pull-ups are
required on port 0 for this operation.
Encryption Array
64 bytes of encryption array are initially unprogrammed (all 1s).
Trademark phrase of Intel Corporation.
2000 Jan 20
29
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
Table 8. EPROM Programming Modes
RST
PSEN
ALE/PROG
EA/VPP
P2.7
P2.6
P3.7
P3.6
Read signature
MODE
1
0
1
1
0
0
0
0
Program code data
1
0
0*
VPP
1
0
1
1
Verify code data
1
0
1
1
0
0
1
1
Pgm encryption table
1
0
0*
VPP
1
0
1
0
Pgm security bit 1
1
0
0*
VPP
1
1
1
1
Pgm security bit 2
1
0
0*
VPP
1
1
0
0
Pgm security bit 3
1
0
0*
VPP
0
1
0
1
NOTES:
1. ‘0’ = Valid low for that pin, ‘1’ = valid high for that pin.
2. VPP = 12.75V ±0.25V.
3. VCC = 5V±10% during programming and verification.
* ALE/PROG receives 5 programming pulses for code data (also for user array; 5 pulses for encryption or security bits) while VPP is held at
12.75V. Each programming pulse is low for 100µs (±10µs) and high for a minimum of 10µs.
Table 9. Program Security Bits for EPROM Devices
PROGRAM LOCK BITS1, 2
SB1
SB2
SB3
PROTECTION DESCRIPTION
1
U
U
U
No Program Security features enabled. (Code verify will still be encrypted by the Encryption Array if
programmed.)
2
P
U
U
MOVC instructions executed from external program memory are disabled from fetching code bytes
from internal memory, EA is sampled and latched on Reset, and further programming of the EPROM
is disabled.
3
P
P
U
Same as 2, also verify is disabled.
4
P
P
P
Same as 3, external execution is disabled. Internal data RAM is not accessible.
NOTES:
1. P – programmed. U – unprogrammed.
2. Any other combination of the security bits is not defined.
2000 Jan 20
30
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
+5V
A0–A7
VCC
P1
P0
1
RST
1
P3.6
EA/VPP
1
P3.7
ALE/PROG
EPROM/OTP
XTAL2
4–6MHz
XTAL1
PGM DATA
+12.75V
5 PULSES TO GROUND
PSEN
0
P2.7
1
P2.6
0
A8–A13
P2.0–P2.5
VSS
SU00873
Figure 26. Programming Configuration
5 PULSES
1
ALE/PROG:
0
1
2
3
4
5
SEE EXPLODED VIEW BELOW
tGHGL = 10µs MIN
tGLGH = 100µs±10µs
1
ALE/PROG:
1
0
SU00875
Figure 27. PROG Waveform
+5V
VCC
A0–A7
P0
P1
1
RST
1
P3.6
1
P3.7
EPROM/OTP
XTAL2
4–6MHz
XTAL1
EA/VPP
1
ALE/PROG
1
PSEN
0
P2.7
0 ENABLE
P2.6
0
P2.0–P2.5
VSS
PGM DATA
P3.4
A8–A13
A14
SU00839A
Figure 28. Program Verification
2000 Jan 20
31
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
EPROM PROGRAMMING AND VERIFICATION CHARACTERISTICS
Tamb = 21°C to +27°C, VCC = 5V±10%, VSS = 0V (See Figure 29)
SYMBOL
PARAMETER
MIN
MAX
UNIT
12.5
13.0
V
50 1
mA
6
MHz
VPP
Programming supply voltage
IPP
Programming supply current
1/tCLCL
Oscillator frequency
tAVGL
Address setup to PROG low
48tCLCL
tGHAX
Address hold after PROG
48tCLCL
tDVGL
Data setup to PROG low
48tCLCL
tGHDX
Data hold after PROG
48tCLCL
tEHSH
P2.7 (ENABLE) high to VPP
48tCLCL
tSHGL
VPP setup to PROG low
10
µs
tGHSL
VPP hold after PROG
10
µs
tGLGH
PROG width
90
tAVQV
Address to data valid
48tCLCL
tELQZ
ENABLE low to data valid
48tCLCL
tEHQZ
Data float after ENABLE
0
tGHGL
PROG high to PROG low
10
4
110
µs
48tCLCL
µs
NOTE:
1. Not tested.
PROGRAMMING*
VERIFICATION*
P1.0–P1.7
P2.0–P2.5
P3.4
(A0 – A14)
ADDRESS
ADDRESS
PORT 0
P0.0 – P0.7
(D0 – D7)
DATA IN
tAVQV
DATA OUT
tDVGL
tAVGL
tGHDX
tGHAX
ALE/PROG
tGLGH
tSHGL
tGHGL
tGHSL
LOGIC 1
LOGIC 1
EA/VPP
LOGIC 0
tEHSH
tELQV
tEHQZ
P2.7
**
SU00871
NOTES:
* FOR PROGRAMMING CONFIGURATION SEE FIGURE 26.
FOR VERIFICATION CONDITIONS SEE FIGURE 28.
**
SEE TABLE 8.
Figure 29. EPROM Programming and Verification
2000 Jan 20
32
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
MASK ROM DEVICES
from the internal memory, EA is latched on Reset and all further
programming of the EPROM is disabled. When security bits 1 and 2
are programmed, in addition to the above, verify mode is disabled.
Security Bits
With none of the security bits programmed the code in the program
memory can be verified. If the encryption table is programmed, the
code will be encrypted when verified. When only security bit 1 (see
Table 10) is programmed, MOVC instructions executed from
external program memory are disabled from fetching code bytes
Encryption Array
64 bytes of encryption array are initially unprogrammed (all 1s).
Table 10. Program Security Bits
PROGRAM LOCK BITS1, 2
SB1
SB2
PROTECTION DESCRIPTION
1
U
U
No Program Security features enabled.
(Code verify will still be encrypted by the Encryption Array if programmed.)
2
P
U
MOVC instructions executed from external program memory are disabled from fetching code bytes from
internal memory, EA is sampled and latched on Reset, and further programming of the EPROM is disabled.
NOTES:
1. P – programmed. U – unprogrammed.
2. Any other combination of the security bits is not defined.
ROM CODE SUBMISSION
When submitting ROM code for the 80C51, the following must be specified:
1. 4k byte user ROM data
2. 64 byte ROM encryption key
3. ROM security bits.
ADDRESS
CONTENT
BIT(S)
COMMENT
0000H to 0FFFH
DATA
7:0
User ROM Data
1000H to 103FH
KEY
7:0
ROM Encryption Key
1040H
SEC
0
ROM Security Bit 1
1040H
SEC
1
ROM Security Bit 2
Security Bit 1: When programmed, this bit has two effects on masked ROM parts:
1. External MOVC is disabled, and
2. EA is latched on Reset.
Security Bit 2: When programmed, this bit inhibits Verify User ROM.
NOTE: Security Bit 2 cannot be enabled unless Security Bit 1 is enabled.
If the ROM Code file does not include the options, the following information must be included with the ROM code.
For each of the following, check the appropriate box, and send to Philips along with the code:
Security Bit #1:
V
Enabled
V
Disabled
Security Bit #2:
V
Enabled
V
Disabled
Encryption:
V
No
V
Yes
2000 Jan 20
If Yes, must send key file.
33
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
DIP40: plastic dual in-line package; 40 leads (600 mil)
2000 Jan 20
34
SOT129-1
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
PLCC44: plastic leaded chip carrier; 44 leads
2000 Jan 20
SOT187-2
35
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
QFP44: plastic quad flat package; 44 leads (lead length 1.3 mm); body 10 x 10 x 1.75 mm
2000 Jan 20
36
SOT307-2
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
NOTES
2000 Jan 20
37
Philips Semiconductors
Product specification
80C51 8-bit microcontroller family
80C51/87C51/80C31
4K/128 OTP/ROM/ROMless, low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
Data sheet status
Data sheet
status
Product
status
Definition [1]
Objective
specification
Development
This data sheet contains the design target or goal specifications for product development.
Specification may change in any manner without notice.
Preliminary
specification
Qualification
This data sheet contains preliminary data, and supplementary data will be published at a later date.
Philips Semiconductors reserves the right to make changes at any time without notice in order to
improve design and supply the best possible product.
Product
specification
Production
This data sheet contains final specifications. Philips Semiconductors reserves the right to make
changes at any time without notice in order to improve design and supply the best possible product.
[1] Please consult the most recently issued datasheet before initiating or completing a design.
Definitions
Short-form specification — The data in a short-form specification is extracted from a full data sheet with the same type number and title. For
detailed information see the relevant data sheet or data handbook.
Limiting values definition — Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one
or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or
at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended
periods may affect device reliability.
Application information — Applications that are described herein for any of these products are for illustrative purposes only. Philips
Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or
modification.
Disclaimers
Life support — These products are not designed for use in life support appliances, devices or systems where malfunction of these products can
reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications
do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application.
Right to make changes — Philips Semiconductors reserves the right to make changes, without notice, in the products, including circuits, standard
cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no
responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these
products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless
otherwise specified.
 Copyright Philips Electronics North America Corporation 2000
All rights reserved. Printed in U.S.A.
Philips Semiconductors
811 East Arques Avenue
P.O. Box 3409
Sunnyvale, California 94088–3409
Telephone 800-234-7381
Date of release: 01-00
Document order number:
2000 Jan 20
38
9397 750 06795