PHILIPS P87C654X2BBD

INTEGRATED CIRCUITS
P83C654X2/P87C654X2
80C51 8-bit microcontroller family
16 kB OTP/ROM, 256B RAM, low voltage (2.7 to 5.5 V),
low power, high speed (30/33 MHz)
Product data
Supersedes data of 2003 Feb 13
2004 Apr 20
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
– Clock can be stopped and resumed
– Idle mode
– Power-down mode
• CMOS and TTL compatible
• Two speed ranges at VCC = 5 V
DESCRIPTION
The devices are Single-Chip 8-Bit Microcontrollers manufactured in
an advanced CMOS process and are derivatives of the 80C51
microcontroller family. The instruction set is 100 % compatible with
the 80C51 instruction set.
– 0 to 30 MHz with 6-clock operation
– 0 to 33 MHz with 12-clock operation
• Parallel programming with 87C51 compatible hardware interface
to programmer
The devices support 6-clock/12-clock mode selection by
programming an OTP bit (OX2) using parallel programming. In
addition, an SFR bit (X2) in the clock control register (CKCON)
also selects between 6-clock/12-clock mode.
• RAM expandable externally to 64 kbytes
• PLCC and LQFP packages
• Extended temperature ranges
• Dual Data Pointers
• Security bits (3 bits)
• Encryption array - 64 bytes
• Seven interrupt sources
• Four interrupt priority levels
• Four 8-bit I/O ports
• Full-duplex enhanced UART
The devices also have four 8-bit I/O ports, three 16-bit timer/event
counters, a multi-source, four-priority-level, nested interrupt structure,
an enhanced UART and on-chip oscillator and timing circuits.
The added features of the P8xC654X2 make it a powerful
microcontroller for applications that require pulse width modulation,
high-speed I/O and up/down counting capabilities such as motor
control.
FEATURES
• 80C51 Central Processing Unit
– 16 kbytes OTP
– Framing error detection
– 256 byte RAM
– Automatic address recognition
• Three 16-bit timers/counters T0, T1 (standard 80C51) and
– Boolean processor
– Fully static operation
additional T2 (capture and compare)
– Low voltage (2.7 V to 5.5 V at 16 MHz) operation
• Programmable clock-out pin
• Asynchronous port reset
• Low EMI (inhibit ALE, slew rate controlled outputs, and 6-clock
• 12-clock operation with selectable 6-clock operation (via software
or via parallel programmer)
• Memory addressing capability
mode)
– Up to 64 kbytes ROM and 64 kbytes RAM
• Wake-up from power-down by an external interrupt
• Watchdog timer
• Power control modes:
ORDERING INFORMATION
OTP
ROM
RAM
Name
Description
Version
Temp Range
(°C)
P83C654X2FA
–
16 KB
256B
PLCC44
plastic leaded chip carrier; 44 leads
SOT187–2
–40 to +85
P83C654X2BBD
–
16 KB
256B
LQFP44
plastic low profile quad flat package; 44 leads;
body 10
10
1.4 mm
SOT389–1
0 to +70
P87C654X2FA
16 KB
–
256B
PLCC44
plastic leaded chip carrier; 44 leads
SOT187–2
–40 to +85
P87C654X2BBD
16 KB
–
256B
LQFP44
plastic low profile quad flat package; 44 leads;
body 10
10
1.4 mm
SOT389–1
0 to +70
Type number
2004 Apr 20
Package
2
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
BLOCK DIAGRAM 1
ACCELERATED 80C51 CPU
(12-CLK MODE, 6-CLK MODE)
16 KB
CODE OTP/ROM
FULL-DUPLEX
ENHANCED UART
256 BYTE
DATA RAM
TIMER 0
TIMER 1
PORT 3
CONFIGURABLE I/Os
TIMER 2
PORT 2
CONFIGURABLE I/Os
WATCHDOG TIMER
PORT 1
CONFIGURABLE I/Os
FAST I2C
PORT 0
CONFIGURABLE I/Os
CRYSTAL OR
RESONATOR
OSCILLATOR
su01728
2004 Apr 20
3
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
BLOCK DIAGRAM (CPU ORIENTED)
P0.0–P0.7
P2.0–P2.7
PORT 0
DRIVERS
PORT 2
DRIVERS
VCC
VSS
RAM ADDR
REGISTER
PORT 0
LATCH
RAM
OTP/ROM
MEMORY
PORT 2
LATCH
8
B
REGISTER
STACK
POINTER
ACC
PROGRAM
ADDRESS
REGISTER
TMP1
TMP2
BUFFER
ALU
SFRs
TIMERS
PSW
PC
INCREMENTER
P.C.A.
8
16
PSEN
ALE
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
SU01751
2004 Apr 20
4
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
LOGIC SYMBOL
Plastic Quad Flat Pack
44
VCC
34
VSS
XTAL1
PORT 0
1
DATA BUS
LQFP
XTAL2
PORT 1
11
RST
EA/VPP
23
T2
T2EX
12
SCL0
SDA0
SCL1
SDA1
PORT 2
PORT 3
SECONDARY FUNCTIONS
PSEN
ALE/PROG
RxD
TxD
INT0
INT1
T0
T1
WR
RD
33
ADDRESS AND
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
ADDRESS BUS
SU01730
PINNING
Function
P1.5
P1.6/SCL0
P1.7/SDA0
RST
P3.0/RxD
VSS32
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
22
Function
VSS1
NIC1
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
VSS22
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
NIC1
P1.0/T2
P1.1/T2EX
P1.2/ECI
P1.3
P1.4
SU01731
Plastic Leaded Chip Carrier
6
1
1. No internal connection
2. May be left open, but it is recommended that VSS2 and VSS3 be
connected to GND to improve EMC performance
40
7
39
LCC
17
29
18
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Function
NIC1
P1.0/T2
P1.1/T2EX
P1.2/ECI
P1.3
P1.4
P1.5
P1.6/SCL0
P1.7/SDA0
RST
P3.0/RxD
VSS32
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
VSS1
NIC1
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
Function
P2.7/A15
PSEN
ALE
VSS22
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
SU01729
1. No internal connection
2. May be left open, but it is recommended that VSS2 and VSS3 be
connected to GND to improve EMC performance
2004 Apr 20
5
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
PIN DESCRIPTIONS
MNEMONIC
PIN NUMBER
TYPE
NAME AND FUNCTION
PLCC
LQFP
VSS
22
16
I
Ground: 0 V reference.
VCC
44
38
I
Power Supply: This is the power supply voltage for normal, idle, and power-down operation.
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.
2–9
40–44,
1–3
I/O
Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups on all pins. 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).
2
3
3
4
5
6
7
8
9
40
41
41
42
43
44
1
2
3
I/O
I
I
I
I/O
I/O
I/O
I/O
I/O
P2.0–P2.72
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.
P3.0–P3.72
11,
13–19
5, 7–13
I/O
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
P8xC654X2, as listed below:
RxD (P3.0): Serial input port
TxD (P3.1): Serial output port
INT0 (P3.2): External interrupt 0
INT1 (P3.3): External interrupt 1
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
RST2
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.
ALE2
33
27
O
Address Latch Enable: Output pulse for latching the LOW byte of the address during an
access to external memory. In normal operation, ALE is emitted at constant rate of 1/6 the
oscillator frequency in 12x clock mode, 1/3 the oscillator frequency in 6x clock mode, and can
be used for external timing or clocking. Note that one ALE pulse is skipped during each access
to external data memory. ALE can be disabled by setting SFR auxiliary.0. With this bit set, ALE
will be active only during a MOVX instruction.
PSEN2
32
26
O
Program Store Enable: The read strobe to external program memory. When 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.
P0.0–0.72
P1.0–P1.72
2004 Apr 20
Alternate functions for P8xC654X2 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
SCL (P1.6): I2C-bus clock line (open drain)
SDA (P1.7): I2C-bus data line (open drain)
6
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
MNEMONIC
PIN NUMBER
TYPE
NAME AND FUNCTION
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. The value on the EA pin is
latched when RST is released and any subsequent changes have no effect.
21
15
I
Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock generator
circuits.
20
14
O
Crystal 2: Output from the inverting oscillator amplifier.
PLCC
LQFP
EA2
35
XTAL1
XTAL2
NOTES:
1. To avoid “latch-up” effect at power-on, the voltage on any pin (other than EA) at any time must not be higher than VCC + 0.5 V or less than
VSS – 0.5 V, respectively.
2. The pins are designed for test mode also.
2004 Apr 20
7
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
SPECIAL FUNCTION REGISTERS
SYMBOL
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
–
–
–
–
Fast/STD
I2C
–
–
AO
xxxx1xx0B
AUXR1#
Auxiliary 1
A2H
–
–
–
LPEP
GPS
0
–
DPS
xxxx00x0B
B*
B register
F0H
F7
F6
F5
F4
F3
F2
F1
F0
00H
CKCON
Clock control
8FH
–
–
–
–
–
–
–
X2
xxxxxxx0B
DPTR:
Data Pointer (2 bytes)
DPH
Data Pointer High
83H
DPL
Data Pointer Low
82H
00H
00H
AF
AE
AD
AC
AB
AA
A9
A8
IEN0*
Interrupt Enable 0
A8H
EA
EC
ES1
ES0
ET1
EX1
ET0
EX0
00000000B
IEN1*
Interrupt Enable 1
E8H
–
–
–
–
–
–
ES2
ET2
xxxxxx00B
BF
BE
BD
BC
BB
BA
B9
B8
PT2
–
PS1
PS0
PT1
PX1
PT0
PX0
B7
B6
B5
B4
B3
B2
B1
B0
PT2H
PPCH
PS1H
PS0H
PT1H
PX1H
PT0H
PX0H
87
86
85
84
83
82
81
80
AD6
AD5
AD4
AD3
AD2
AD1
AD0
IP*#
IPH#
Interrupt Priority
Interrupt Priority High
B8H
B7H
P0*
Port 0
80H
AD7
97
96
95
94
93
92
91
90
P1*#
Port 1
90H
SDA
SCL
–
–
–
–
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
P2*
Port 2
A0H
00000000B
00000000B
FFH
FFH
FFH
P3*
Port 3
B0H
RD
WR
T1
T0
INT1
INT0
TxD
RxD
FFH
PCON#1
Power Control
87H
SMOD1
SMOD0
–
POF
GF1
GF0
PD
IDL
00xx0000B
D7
D6
D5
D4
D3
D2
D1
D0
PSW*
Program Status Word
D0H
CY
AC
F0
RS1
RS0
OV
F1
P
RCAP2H#
Timer 2 Capture High
CBH
00H
RCAP2L#
Timer 2 Capture Low
CAH
00H
SADDR#
Slave Address
A9H
00H
SADEN#
Slave Address Mask
B9H
00H
SBUF
Serial Data Buffer
99H
xxxxxxxxB
SCON*
Serial Control
98H
SP
Stack Pointer
81H
TCON*
Timer Control
88H
9F
9E
9D
9C
9B
9A
99
98
SM0/FE
SM1
SM2
REN
TB8
RB8
TI
RI
00000000B
00H
07H
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
T2CON*
Timer 2 Control
C8H
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/
RL2
T2MOD#
Timer 2 Mode Control
C9H
–
–
–
–
–
–
T2OE
DCEN
TH0
Timer High 0
8CH
00H
TH1
Timer High 1
8DH
00H
TH2#
Timer High 2
CDH
00H
2004 Apr 20
8
00H
xxxxxx00B
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
SYMBOL
DESCRIPTION
DIRECT
ADDRESS
BIT ADDRESS, SYMBOL, OR ALTERNATIVE PORT FUNCTION
MSB
LSB
RESET
VALUE
TL0
Timer Low 0
8AH
00H
TL1
Timer Low 1
8BH
00H
TL2#
Timer Low 2
CCH
TMOD
Timer Mode
89H
GATE
C/T
M1
M0
GATE
C/T
M1
M0
00H
S1CON
I2C Control
D8H
CR2
ENA1
STA
STO
SI
AA
CR1
CR0
00H
S1STA
I2C STATUS
D9H
SC4
SC3
SC2
SC1
SC0
0
0
0
F8H
S1DAT
I2C DATA
DAH
S1ADR
I2C ADDRESS
DBH
00H
00H
GC
WDTRST
Watchdog Reset Timer
A6H
* SFRs are bit addressable.
# SFRs are modified from or added to the 80C51 SFRs.
– Reserved bits.
1. Reset value depends on reset source.
2004 Apr 20
9
00H
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
OX2, when programmed (6-clock mode), supersedes the X2 bit
(CKCON.0). The CKCON register is shown below in Figure 1.
CLOCK CONTROL REGISTER (CKCON)
This device allows control of the 6-clock/12-clock mode by means of
both an SFR bit (X2) and an OTP bit. The OTP clock control bit
CKCON
Address = 8Fh
Reset Value = x0000000B
Not Bit Addressable
7
–
BIT
CKCON.7
CKCON.6
CKCON.5
CKCON.4
CKCON.3
CKCON.2
CKCON.1
CKCON.0
SYMBOL
–
X2
6
5
4
3
2
1
0
–
–
–
–
–
–
X2
FUNCTION
Reserved.
Reserved.
Reserved.
Reserved.
Reserved.
Reserved.
Reserved.
CPU clock; 1 = 6 clocks for each machine cycle, 0 = 12 clocks for each machine cycle
SU01689
Figure 1. Clock control (CKCON) register
Also please note that the clock divider applies to the serial port for
modes 0 and 2 (fixed baud rate modes). This is because modes 1
and 3 (variable baud rate modes) use either Timer 1 or Timer 2.
Table 1.
Below is the truth table for the CPU clock mode.
2004 Apr 20
10
OX2 clock mode bit
(can only be set by
parallel programmer)
X2 bit
(CKCON.0)
CPU clock mode
erased
0
12-clock mode
(default)
erased
1
6-clock mode
programmed
X
6-clock mode
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
OSCILLATOR CHARACTERISTICS
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 10 ms).
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.
To drive the device from an external clock source, XTAL1 should be
driven while XTAL2 is left unconnected. Minimum and maximum
high and low times specified in the data sheet must be observed.
With an external interrupt, INT0 and 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.
This device is configured at the factory to operate using 12 clock
periods per machine cycle, referred to in this datasheet as “12-clock
mode”. It may be optionally configured on commercially available
EPROM programming equipment to operate at 6 clocks per machine
cycle, referred to in this datasheet as “6-clock mode”. (This yields
performance equivalent to twice that of standard 80C51 family
devices). Also see next page.
POWER-OFF FLAG
The Power-Off Flag (POF) is set by on-chip circuitry when the VCC
level on the P8xC654X2 rises from 0 to 5 V. The POF bit can be set
or cleared by software allowing a user to determine if the reset is the
result of a power-on or a warm start after power-down. The VCC
level must remain above 3 V for the POF to remain unaffected by
the VCC level.
RESET
A reset is accomplished by holding the RST pin HIGH for at least
two machine cycles (12 oscillator periods in 6-clock mode, or 24
oscillator periods in 12-clock mode), while the oscillator is running.
To insure a good power-on 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. At power-on, the voltage on
VCC and RST must come up at the same time for a proper start-up.
Low-Power EPROM operation (LPEP)
The EPROM array contains some analog circuits that are not
required when VCC is less than 4 V, but are required for a VCC
greater than 4 V. The LPEP bit (AUXR.4), when set, will power-down
these analog circuits resulting in a reduced supply current. This bit
should be set ONLY for applications that operate at a VCC less than
4 V.
Ports 1, 2, and 3 will asynchronously be driven to their reset
condition when a voltage above VIH (min.) is applied to RESET. The
value on the EA pin is latched when RST is deasserted and has no
further effect.
Design Consideration
When the idle mode is terminated by a hardware reset, the device
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.
LOW POWER MODES
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.
ONCE 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:
Idle Mode
In the 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.
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 device 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.
Power-Down Mode
Programmable Clock-Out
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 V and care must be taken to return VCC to the
minimum specified operating voltages before the Power-down mode
is terminated.
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 122 Hz to 8 MHz at
a 16 MHz operating frequency (61 Hz to 4 MHz in 12-clock mode).
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.
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 interrupt allows both the SFRs and the
on-chip RAM to retain their values.
2004 Apr 20
11
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Where (RCAP2H,RCAP2L) = the content of RCAP2H and RCAP2L
taken as a 16-bit unsigned integer.
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:
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.
Oscillator Frequency
(65536 * RCAP2H, RCAP2L)
n
n=
2 in 6-clock mode
4 in 12-clock mode
Table 2. External Pin Status During Idle and Power-Down Mode
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
2004 Apr 20
12
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
TIMER 0 AND TIMER 1 OPERATION
Timer 0 and Timer 1
Mode 1
Mode 1 is the same as Mode 0, except that the Timer register is
being run with all 16 bits.
The “Timer” or “Counter” function is selected by control bits C/T in
the Special Function Register TMOD. These two Timer/Counters
have four operating modes, which are selected by bit-pairs (M1, M0)
in TMOD. Modes 0, 1, and 2 are the same for both Timers/Counters.
Mode 3 is different. The four operating modes are described in the
following text.
Mode 2
Mode 2 configures the Timer register as an 8-bit Counter (TLn) with
automatic reload, as shown in Figure 5. Overflow from TLn not only
sets TFn, but also reloads TLn with the contents of THn, which is
preset by software. The reload leaves THn unchanged.
Mode 0
Putting either Timer into Mode 0 makes it look like an 8048 Timer,
which is an 8-bit Counter with a divide-by-32 prescaler. Figure 3
shows the Mode 0 operation.
Mode 2 operation is the same for Timer 0 as for Timer 1.
Mode 3
Timer 1 in Mode 3 simply holds its count. The effect is the same as
setting TR1 = 0.
In this mode, the Timer register is configured as a 13-bit register. As
the count rolls over from all 1s to all 0s, it sets the Timer interrupt
flag TFn. The counted input is enabled to the Timer when TRn = 1
and either GATE = 0 or INTn = 1. (Setting GATE = 1 allows the
Timer to be controlled by external input INTn, to facilitate pulse width
measurements). TRn is a control bit in the Special Function Register
TCON (Figure 4).
Timer 0 in Mode 3 establishes TL0 and TH0 as two separate
counters. The logic for Mode 3 on Timer 0 is shown in Figure 6. TL0
uses the Timer 0 control bits: C/T, GATE, TR0, and TF0 as well as
pin INT0. TH0 is locked into a timer function (counting machine
cycles) and takes over the use of TR1 and TF1 from Timer 1. Thus,
TH0 now controls the “Timer 1” interrupt.
The 13-bit register consists of all 8 bits of THn and the lower 5 bits
of TLn. The upper 3 bits of TLn are indeterminate and should be
ignored. Setting the run flag (TRn) does not clear the registers.
Mode 3 is provided for applications requiring an extra 8-bit timer on
the counter. With Timer 0 in Mode 3, an 80C51 can look like it has
three Timer/Counters. When Timer 0 is in Mode 3, Timer 1 can be
turned on and off by switching it out of and into its own Mode 3, or
can still be used by the serial port as a baud rate generator, or in
fact, in any application not requiring an interrupt.
Mode 0 operation is the same for Timer 0 as for Timer 1. There are
two different GATE bits, one for Timer 1 (TMOD.7) and one for Timer
0 (TMOD.3).
TMOD
Address = 89H
Reset Value = 00H
Not Bit Addressable
7
6
5
4
3
2
1
0
GATE
C/T
M1
M0
GATE
C/T
M1
M0
TIMER 1
BIT
TMOD.3/
TMOD.7
TMOD.2/
TMOD.6
SYMBOL
GATE
C/T
TIMER 0
FUNCTION
Gating control when set. Timer/Counter “n” is enabled only while “INTn” pin is high and
“TRn” control pin is set. when cleared Timer “n” is enabled whenever “TRn” control bit is set.
Timer or Counter Selector cleared for Timer operation (input from internal system clock.)
Set for Counter operation (input from “Tn” input pin).
M1
M0
OPERATING
0
0
8048 Timer: “TLn” serves as 5-bit prescaler.
0
1
16-bit Timer/Counter: “THn” and “TLn” are cascaded; there is no prescaler.
1
0
8-bit auto-reload Timer/Counter: “THn” holds a value which is to be reloaded
into “TLn” each time it overflows.
1
1
(Timer 0) TL0 is an 8-bit Timer/Counter controlled by the standard Timer 0 control bits.
TH0 is an 8-bit timer only controlled by Timer 1 control bits.
1
1
(Timer 1) Timer/Counter 1 stopped.
SU01580
Figure 2. Timer/Counter 0/1 Mode Control (TMOD) Register
2004 Apr 20
13
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
÷ d*
OSC
C/T = 0
TLn
(5 Bits)
THn
(8 Bits)
TFn
Interrupt
C/T = 1
Control
Tn Pin
TRn
Timer n
Gate bit
INTn Pin
*d = 6 in 6-clock mode; d = 12 in 12-clock mode.
SU01618
Figure 3. Timer/Counter 0/1 Mode 0: 13-Bit Timer/Counter
TCON
Address = 88H
Reset Value = 00H
Bit Addressable
7
TF1
BIT
TCON.7
SYMBOL
TF1
TCON.6
TCON.5
TR1
TF0
TCON.4
TCON.3
TR0
IE1
TCON.2
IT1
TCON.1
IE0
TCON.0
IT0
6
5
4
3
2
1
0
TR1
TF0
TR0
IE1
IT1
IE0
IT0
FUNCTION
Timer 1 overflow flag. Set by hardware on Timer/Counter overflow.
Cleared by hardware when processor vectors to interrupt routine, or clearing the bit in software.
Timer 1 Run control bit. Set/cleared by software to turn Timer/Counter on/off.
Timer 0 overflow flag. Set by hardware on Timer/Counter overflow.
Cleared by hardware when processor vectors to interrupt routine, or by clearing the bit in software.
Timer 0 Run control bit. Set/cleared by software to turn Timer/Counter on/off.
Interrupt 1 Edge flag. Set by hardware when external interrupt edge detected.
Cleared when interrupt processed.
Interrupt 1 type control bit. Set/cleared by software to specify falling edge/low level triggered
external interrupts.
Interrupt 0 Edge flag. Set by hardware when external interrupt edge detected.
Cleared when interrupt processed.
Interrupt 0 Type control bit. Set/cleared by software to specify falling edge/low level
triggered external interrupts.
SU01516
Figure 4. Timer/Counter 0/1 Control (TCON) Register
2004 Apr 20
14
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
÷ d*
OSC
C/T = 0
TLn
(8 Bits)
TFn
Interrupt
C/T = 1
Control
Tn Pin
Reload
TRn
Timer n
Gate bit
THn
(8 Bits)
INTn Pin
SU01619
*d = 6 in 6-clock mode; d = 12 in 12-clock mode.
Figure 5. Timer/Counter 0/1 Mode 2: 8-Bit Auto-Reload
÷ d*
OSC
C/T = 0
TL0
(8 Bits)
TF0
Interrupt
TH0
(8 Bits)
TF1
Interrupt
C/T = 1
Control
T0 Pin
TR0
Timer 0
Gate bit
INT0 Pin
OSC
÷ d*
Control
TR1
*d = 6 in 6-clock mode; d = 12 in 12-clock mode.
SU01620
Figure 6. Timer/Counter 0 Mode 3: Two 8-Bit Counters
2004 Apr 20
15
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Counter Enable) which is located in the T2MOD register (see
Figure 9). 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.
TIMER 2 OPERATION
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 7). 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.
Figure 10 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.
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
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 8 (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/6 pulses
(osc/12 in 12-clock mode).).
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.
In Figure 11 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.
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.
Auto-Reload Mode (Up or Down Counter)
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.
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
(MSB)
TF2
(LSB)
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/6 in 6-clock mode or OSC/12 in 12-clock mode)
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.
SU01251
Figure 7. Timer/Counter 2 (T2CON) Control Register
2004 Apr 20
16
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
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)
OSC
MODE
÷ n*
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
SU01252
* n = 6 in 6-clock mode, or 12 in 12-clock mode.
Figure 8. Timer 2 in Capture Mode
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 9. Timer 2 Mode (T2MOD) Control Register
2004 Apr 20
17
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
÷ n*
OSC
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
SU01253
EXEN2
* n = 6 in 6-clock mode, or 12 in 12-clock mode.
Figure 10. Timer 2 in Auto-Reload Mode (DCEN = 0)
(DOWN COUNTING RELOAD VALUE)
FFH
FFH
TOGGLE
EXF2
OSC
÷ n*
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)
* n = 6 in 6-clock mode, or 12 in 12-clock mode.
SU01254
Figure 11. Timer 2 Auto Reload Mode (DCEN = 1)
2004 Apr 20
T2EX PIN
18
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Timer 1
Overflow
n = 1 in 6-clock mode
n = 2 in 12-clock mode
÷2
“0”
÷n
OSC
“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.
SU01629
Figure 12. Timer 2 in Baud Rate Generator Mode
Table 4.
The baud rates in modes 1 and 3 are determined by Timer 2’s
overflow rate given below:
Timer 2 Generated Commonly Used
Baud Rates
Baud Rate
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.
Timer 2
12-clock
mode
6-clock
mode
Osc Freq
375 k
9.6 k
4.8 k
2.4 k
1.2 k
300
110
300
110
750 k
19.2 k
9.6 k
4.8 k
2.4 k
600
220
600
220
12 MHz
12 MHz
12 MHz
12 MHz
12 MHz
12 MHz
12 MHz
6 MHz
6 MHz
RCAP2H
RCAP2L
FF
FF
FF
FF
FE
FB
F2
FD
F9
FF
D9
B2
64
C8
1E
AF
8F
57
Usually, as a timer it would increment every machine cycle (i.e.,
1/ the oscillator frequency in 6-clock mode, 1/ the oscillator
6
12
frequency in 12-clock mode). As a baud rate generator, it
increments at the oscillator frequency in 6-clock mode (OSC/2 in
12-clock mode). Thus the baud rate formula is as follows:
Modes 1 and 3 Baud Rates =
Oscillator Frequency
[ n * [65536 * (RCAP2H, RCAP2L)]]
Baud Rate Generator Mode
*n=
Bits TCLK and/or RCLK in T2CON (Table 4) 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.
Where: (RCAP2H, RCAP2L)= The content of RCAP2H and
RCAP2L taken as a 16-bit unsigned integer.
The Timer 2 as a baud rate generator mode shown in Figure 12, 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.
Figure 12 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.
2004 Apr 20
16 in 6-clock mode
32 in 12-clock mode
19
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
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;
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.
If Timer 2 is being clocked internally, the baud rate is:
Table 4 shows commonly used baud rates and how they can be
obtained from Timer 2.
To obtain the reload value for RCAP2H and RCAP2L, the above
equation can be rewritten as:
Baud Rate +
*n=
f OSC
[65536 * (RCAP2H, RCAP2L)]]
16 in 6-clock mode
32 in 12-clock mode
Where fosc = Oscillator Frequency
Summary of Baud Rate Equations
RCAP2H, RCAP2L + 65536 *
Timer 2 is in baud rate generating mode. If Timer 2 is being clocked
through pin T2 (P1.0) the baud rate is:
ǒ
n*
f OSC
Baud Rate
Ǔ
Timer/Counter 2 Set-up
Baud Rate + Timer 2 Overflow Rate
16
Table 5.
[ n*
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.
Timer 2 as a Timer
T2CON
MODE
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
TMOD
MODE
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.
2004 Apr 20
20
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
The slaves that weren’t being addressed leave their SM2s set and
go on about their business, ignoring the coming data bytes.
FULL-DUPLEX ENHANCED UART
Standard UART operation
SM2 has no effect in Mode 0, and in Mode 1 can be used to check
the validity of the stop bit. In a Mode 1 reception, if SM2 = 1, the
receive interrupt will not be activated unless a valid stop bit is
received.
The serial port is full duplex, meaning it can transmit and receive
simultaneously. It is also receive-buffered, meaning it can
commence reception of a second byte before a previously received
byte has been read from the register. (However, if the first byte still
hasn’t been read by the time reception of the second byte is
complete, one of the bytes will be lost.) The serial port receive and
transmit registers are both accessed at Special Function Register
SBUF. Writing to SBUF loads the transmit register, and reading
SBUF accesses a physically separate receive register.
Serial Port Control Register
The serial port control and status register is the Special Function
Register SCON, shown in Figure 13. This register contains not only
the mode selection bits, but also the 9th data bit for transmit and
receive (TB8 and RB8), and the serial port interrupt bits (TI and RI).
The serial port can operate in 4 modes:
Mode 0:
Serial data enters and exits through RxD. TxD outputs
the shift clock. 8 bits are transmitted/received (LSB first).
The baud rate is fixed at 1/12 the oscillator frequency in
12-clock mode or 1/6 the oscillator frequency in 6-clock
mode.
Mode 1:
10 bits are transmitted (through TxD) or received
(through RxD): a start bit (0), 8 data bits (LSB first), and
a stop bit (1). On receive, the stop bit goes into RB8 in
Special Function Register SCON. The baud rate is
variable.
Mode 2:
Mode 3:
Baud Rates
The baud rate in Mode 0 is fixed: Mode 0 Baud Rate = Oscillator
Frequency / 12 (12-clock mode) or / 6 (6-clock mode). The baud
rate in Mode 2 depends on the value of bit SMOD in Special
Function Register PCON. If SMOD = 0 (which is the value on reset),
and the port pins in 12-clock mode, the baud rate is 1/64 the
oscillator frequency. If SMOD = 1, the baud rate is 1/32 the oscillator
frequency. In 6-clock mode, the baud rate is 1/32 or 1/16 the
oscillator frequency, respectively.
Mode 2 Baud Rate =
2 SMOD
n
11 bits are transmitted (through TxD) or received
(through RxD): start bit (0), 8 data bits (LSB first), a
programmable 9th data bit, and a stop bit (1). On
Transmit, the 9th data bit (TB8 in SCON) can be
assigned the value of 0 or 1. Or, for example, the parity
bit (P, in the PSW) could be moved into TB8. On receive,
the 9th data bit goes into RB8 in Special Function
Register SCON, while the stop bit is ignored. The baud
rate is programmable to either 1/32 or 1/64 the oscillator
frequency in 12-clock mode or 1/16 or 1/32 the oscillator
frequency in 6-clock mode.
Where:
n = 64 in 12-clock mode, 32 in 6-clock mode
The baud rates in Modes 1 and 3 are determined by the Timer 1 or
Timer 2 overflow rate.
Using Timer 1 to Generate Baud Rates
When Timer 1 is used as the baud rate generator (T2CON.RCLK
= 0, T2CON.TCLK = 0), the baud rates in Modes 1 and 3 are
determined by the Timer 1 overflow rate and the value of SMOD as
follows:
11 bits are transmitted (through TxD) or received
(through RxD): a start bit (0), 8 data bits (LSB first), a
programmable 9th data bit, and a stop bit (1). In fact,
Mode 3 is the same as Mode 2 in all respects except
baud rate. The baud rate in Mode 3 is variable.
Mode 1, 3 Baud Rate =
2 SMOD
n
(Timer 1 Overflow Rate)
Where:
In all four modes, transmission is initiated by any instruction that
uses SBUF as a destination register. Reception is initiated in Mode 0
by the condition RI = 0 and REN = 1. Reception is initiated in the
other modes by the incoming start bit if REN = 1.
n = 32 in 12-clock mode, 16 in 6-clock mode
The Timer 1 interrupt should be disabled in this application. The
Timer itself can be configured for either “timer” or “counter”
operation, and in any of its 3 running modes. In the most typical
applications, it is configured for “timer” operation, in the auto-reload
mode (high nibble of TMOD = 0010B). In that case the baud rate is
given by the formula:
Multiprocessor Communications
Modes 2 and 3 have a special provision for multiprocessor
communications. In these modes, 9 data bits are received. The 9th
one goes into RB8. Then comes a stop bit. The port can be
programmed such that when the stop bit is received, the serial port
interrupt will be activated only if RB8 = 1. This feature is enabled by
setting bit SM2 in SCON. A way to use this feature in multiprocessor
systems is as follows:
Mode 1, 3 Baud Rate =
2 SMOD
n
Oscillator Frequency
12 [256–(TH1)]
Where:
When the master processor wants to transmit a block of data to one
of several slaves, it first sends out an address byte which identifies
the target slave. An address byte differs from a data byte in that the
9th bit is 1 in an address byte and 0 in a data byte. With SM2 = 1, no
slave will be interrupted by a data byte. An address byte, however,
will interrupt all slaves, so that each slave can examine the received
byte and see if it is being addressed. The addressed slave will clear
its SM2 bit and prepare to receive the data bytes that will be coming.
2004 Apr 20
(Oscillator Frequency)
n = 32 in 12-clock mode, 16 in 6-clock mode
One can achieve very low baud rates with Timer 1 by leaving the
Timer 1 interrupt enabled, and configuring the Timer to run as a
16-bit timer (high nibble of TMOD = 0001B), and using the Timer 1
interrupt to do a 16-bit software reload. Figure 14 lists various
commonly used baud rates and how they can be obtained from
Timer 1.
21
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
SCON
Address = 98H
Bit Addressable
Reset Value = 00H
7
6
5
4
3
2
1
0
SM0
SM1
SM2
REN
TB8
RB8
TI
RI
Where SM0, SM1 specify the serial port mode, as follows:
SM0
0
0
1
1
SM1
0
1
0
1
Mode
0
1
2
3
Description
shift register
8-bit UART
9-bit UART
9-bit UART
Baud Rate
fOSC/12 (12-clock mode) or fOSC/6 (6-clock mode)
variable
fOSC/64 or fOSC/32 (12-clock mode) or fOSC/32 or fOSC/16 (6-clock mode)
variable
SM2
Enables the multiprocessor communication feature in Modes 2 and 3. In Mode 2 or 3, if SM2 is set to 1, then Rl will not be
activated if the received 9th data bit (RB8) is 0. In Mode 1, if SM2=1 then RI will not be activated if a valid stop bit was not
received. 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, is the 9th data bit that was received. In Mode 1, it SM2=0, RB8 is the stop bit that was received. In Mode 0,
RB8 is not used.
TI
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.
RI
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.
SU01626
Figure 13. Serial Port Control (SCON) Register
Timer 1
Baud Rate
Mode
12-clock mode
6-clock mode
Mode 0 Max
Mode 2 Max
Mode 1, 3 Max
Mode 1, 3
1.67 MHz
625 k
104.2 k
19.2 k
9.6 k
4.8 k
2.4 k
1.2 k
137.5
110
110
3.34 MHz
1250 k
208.4 k
38.4 k
19.2 k
9.6 k
4.8 k
2.4 k
275
220
220
fosc
SMOD
20 MHz
20 MHz
20 MHz
11.059 MHz
11.059 MHz
11.059 MHz
11.059 MHz
11.059 MHz
11.986 MHz
6 MHz
12 MHz
X
1
1
1
0
0
0
0
0
0
0
C/T
Mode
Reload Value
X
X
0
0
0
0
0
0
0
0
0
X
X
2
2
2
2
2
2
2
2
1
X
X
FFH
FDH
FDH
FAH
F4H
E8H
1DH
72H
FEEBH
Figure 14. Timer 1 Generated Commonly Used Baud Rates
More About Mode 0
Serial data enters and exits through RxD. TxD outputs the shift
clock. 8 bits are transmitted/received: 8 data bits (LSB first). The
baud rate is fixed a 1/12 the oscillator frequency (12-clock mode) or
1/6 the oscillator frequency (6-clock mode).
S6P2 of every machine cycle in which SEND is active, the contents
of the transmit shift are shifted to the right one position.
As data bits shift out to the right, zeros come in from the left. When
the MSB of the data byte is at the output position of the shift register,
then the 1 that was initially loaded into the 9th position, is just to the
left of the MSB, and all positions to the left of that contain zeros.
This condition flags the TX Control block to do one last shift and
then deactivate SEND and set T1. Both of these actions occur at
S1P1 of the 10th machine cycle after “write to SBUF.”
Figure 15 shows a simplified functional diagram of the serial port in
Mode 0, and associated timing.
Transmission is initiated by any instruction that uses SBUF as a
destination register. The “write to SBUF” signal at S6P2 also loads a
1 into the 9th position of the transmit shift register and tells the TX
Control block to commence a transmission. The internal timing is
such that one full machine cycle will elapse between “write to SBUF”
and activation of SEND.
Reception is initiated by the condition REN = 1 and R1 = 0. At S6P2
of the next machine cycle, the RX Control unit writes the bits
11111110 to the receive shift register, and in the next clock phase
activates RECEIVE.
RECEIVE enable SHIFT CLOCK to the alternate output function line
of P3.1. SHIFT CLOCK makes transitions at S3P1 and S6P1 of
every machine cycle. At S6P2 of every machine cycle in which
RECEIVE is active, the contents of the receive shift register are
SEND enables the output of the shift register to the alternate output
function line of P3.0 and also enable SHIFT CLOCK to the alternate
output function line of P3.1. SHIFT CLOCK is LOW during S3, S4,
and S5 of every machine cycle, and HIGH during S6, S1, and S2. At
2004 Apr 20
22
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
shifted to the left one position. The value that comes in from the right
is the value that was sampled at the P3.0 pin at S5P2 of the same
machine cycle.
whether the above conditions are met or not, the unit goes back to
looking for a 1-to-0 transition in RxD.
More About Modes 2 and 3
Eleven bits are transmitted (through TxD), or received (through
RxD): a start bit (0), 8 data bits (LSB first), a programmable 9th data
bit, and a stop bit (1). On transmit, the 9th data bit (TB8) can be
assigned the value of 0 or 1. On receive, the 9the data bit goes into
RB8 in SCON. The baud rate is programmable to either 1/32 or 1/64
(12-clock mode) or 1/16 or 1/32 the oscillator frequency (6-clock
mode) the oscillator frequency in Mode 2. Mode 3 may have a
variable baud rate generated from Timer 1 or Timer 2.
As data bits come in from the right, 1s shift out to the left. When the
0 that was initially loaded into the rightmost position arrives at the
leftmost position in the shift register, it flags the RX Control block to
do one last shift and load SBUF. At S1P1 of the 10th machine cycle
after the write to SCON that cleared RI, RECEIVE is cleared as RI is
set.
More About Mode 1
Ten bits are transmitted (through TxD), or received (through RxD): a
start bit (0), 8 data bits (LSB first), and a stop bit (1). On receive, the
stop bit goes into RB8 in SCON. In the 80C51 the baud rate is
determined by the Timer 1 or Timer 2 overflow rate.
Figures 17 and 18 show a functional diagram of the serial port in
Modes 2 and 3. The receive portion is exactly the same as in Mode
1. The transmit portion differs from Mode 1 only in the 9th bit of the
transmit shift register.
Figure 16 shows a simplified functional diagram of the serial port in
Mode 1, and associated timings for transmit receive.
Transmission is initiated by any instruction that uses SBUF as a
destination register. The “write to SBUF” signal also loads TB8 into
the 9th bit position of the transmit shift register and flags the TX
Control unit that a transmission is requested. Transmission
commences at S1P1 of the machine cycle following the next rollover
in the divide-by-16 counter. (Thus, the bit times are synchronized to
the divide-by-16 counter, not to the “write to SBUF” signal.)
Transmission is initiated by any instruction that uses SBUF as a
destination register. The “write to SBUF” signal also loads a 1 into
the 9th bit position of the transmit shift register and flags the TX
Control unit that a transmission is requested. Transmission actually
commences at S1P1 of the machine cycle following the next rollover
in the divide-by-16 counter. (Thus, the bit times are synchronized to
the divide-by-16 counter, not to the “write to SBUF” signal.)
The transmission begins with activation of SEND, which puts the
start bit at TxD. One bit time later, DATA is activated, which enables
the output bit of the transmit shift register to TxD. The first shift pulse
occurs one bit time after that. The first shift clocks a 1 (the stop bit)
into the 9th bit position of the shift register. Thereafter, only zeros
are clocked in. Thus, as data bits shift out to the right, zeros are
clocked in from the left. When TB8 is at the output position of the
shift register, then the stop bit is just to the left of TB8, and all
positions to the left of that contain zeros. This condition flags the TX
Control unit to do one last shift and then deactivate SEND and set
TI. This occurs at the 11th divide-by-16 rollover after “write to SUBF.”
The transmission begins with activation of SEND which puts the
start bit at TxD. One bit time later, DATA is activated, which enables
the output bit of the transmit shift register to TxD. The first shift pulse
occurs one bit time after that.
As data bits shift out to the right, zeros are clocked in from the left.
When the MSB of the data byte is at the output position of the shift
register, then the 1 that was initially loaded into the 9th position is
just to the left of the MSB, and all positions to the left of that contain
zeros. This condition flags the TX Control unit to do one last shift
and then deactivate SEND and set TI. This occurs at the 10th
divide-by-16 rollover after “write to SBUF.”
Reception is initiated by a detected 1-to-0 transition at RxD. For this
purpose RxD is sampled at a rate of 16 times whatever baud rate
has been established. When a transition is detected, the
divide-by-16 counter is immediately reset, and 1FFH is written to the
input shift register.
Reception is initiated by a detected 1-to-0 transition at RxD. For this
purpose RxD is sampled at a rate of 16 times whatever baud rate
has been established. When a transition is detected, the
divide-by-16 counter is immediately reset, and 1FFH is written into
the input shift register. Resetting the divide-by-16 counter aligns its
rollovers with the boundaries of the incoming bit times.
At the 7th, 8th, and 9th counter states of each bit time, the bit
detector samples the value of R-D. The value accepted is the value
that was seen in at least 2 of the 3 samples. If the value accepted
during the first bit time is not 0, the receive circuits are reset and the
unit goes back to looking for another 1-to-0 transition. If the start bit
proves valid, it is shifted into the input shift register, and reception of
the rest of the frame will proceed.
The 16 states of the counter divide each bit time into 16ths. At the
7th, 8th, and 9th counter states of each bit time, the bit detector
samples the value of RxD. The value accepted is the value that was
seen in at least 2 of the 3 samples. This is done for noise rejection.
If the value accepted during the first bit time is not 0, the receive
circuits are reset and the unit goes back to looking for another 1-to-0
transition. This is to provide rejection of false start bits. If the start bit
proves valid, it is shifted into the input shift register, and reception of
the rest of the frame will proceed.
As data bits come in from the right, 1s shift out to the left. When the
start bit arrives at the leftmost position in the shift register (which in
Modes 2 and 3 is a 9-bit register), it flags the RX Control block to do
one last shift, load SBUF and RB8, and set RI.
The signal to load SBUF and RB8, and to set RI, will be generated
if, and only if, the following conditions are met at the time the final
shift pulse is generated.
1. RI = 0, and
2. Either SM2 = 0, or the received 9th data bit = 1.
As data bits come in from the right, 1s shift out to the left. When the
start bit arrives at the leftmost position in the shift register (which in
mode 1 is a 9-bit register), it flags the RX Control block to do one
last shift, load SBUF and RB8, and set RI. The signal to load SBUF
and RB8, and to set RI, will be generated if, and only if, the following
conditions are met at the time the final shift pulse is generated.:
1. RI = 0, and
2. Either SM2 = 0, or the received stop bit = 1.
If either of these conditions is not met, the received frame is
irretrievably lost, and RI is not set. If both conditions are met, the
received 9th data bit goes into RB8, and the first 8 data bits go into
SBUF. One bit time later, whether the above conditions were met or
not, the unit goes back to looking for a 1-to-0 transition at the RxD
input.
If either of these two conditions is not met, the received frame is
irretrievably lost. If both conditions are met, the stop bit goes into
RB8, the 8 data bits go into SBUF, and RI is activated. At this time,
2004 Apr 20
P83C654X2/P87C654X2
23
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
80C51 Internal Bus
Write
to
SBUF
S
D
Q
RxD
P3.0 Alt
Output
Function
SBUF
CL
Zero Detector
Start
Shift
TX Control
S6
T1
TX Clock
Send
Serial
Port
Interrupt
R1
RX Clock
Receive
RX Control
REN
RI
Start
1
1
1
TxD
P3.1 Alt
Output
Function
Shift
Clock
Shift
1
1
1
1
0
MSB
LSB
RxD
P3.0 Alt
Input
Function
Input Shift Register
Shift
Load
SBUF
LSB
MSB
SBUF
Read
SBUF
80C51 Internal Bus
S4 . .
S1 . . . . S6 S1 . . . . S6 S1 . . . . S6 S1 . . . . S6 S1 . . . . S6 S1 . . . . S6 S1 . . . . S6 S1 . . . . S6 S1 . . . . S6 S1 . . . . S6 S1
ALE
Write to SBUF
S6P2
Send
Shift
Transmit
RxD (Data Out)
D0
D1
D2
D3
D4
D5
D6
D7
TxD (Shift Clock)
S3P1
TI
S6P1
Write to SCON (Clear RI)
RI
Receive
Shift
RxD (Data In)
Receive
D0
D1
D2
D3
D4
D5
D6
D7
S5P2
TxD (Shift Clock)
SU00539
Figure 15. Serial Port Mode 0
2004 Apr 20
24
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Timer 1
Overflow
80C51 Internal Bus
TB8
÷2
SMOD = 0
SMOD = 1
Write
to
SBUF
S
D
Q
SBUF
TxD
CL
Zero Detector
Start
Data
Shift
TX Control
÷ 16
T1
Send
RX Clock RI
Load
SBUF
TX Clock
Serial
Port
Interrupt
÷ 16
Sample
RX Control
1-to-0
Transition
Detector
Shift
Start
1FFH
Bit Detector
Input Shift Register
(9 Bits)
Shift
RxD
Load
SBUF
SBUF
Read
SBUF
80C51 Internal Bus
TX
Clock
Write to SBUF
Send
Data
S1P1
Transmit
Shift
TxD
Start Bit
D0
D1
D2
D3
D4
D5
D6
D7
Stop Bit
D0
D1
D2
D3
D4
D5
D6
D7
Stop Bit
TI
÷ 16 Reset
RX
Clock
RxD
Bit Detector
Sample Times
Start
Bit
Receive
Shift
RI
SU00540
Figure 16. Serial Port Mode 1
2004 Apr 20
25
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
80C51 Internal Bus
TB8
Write
to
SBUF
S
D
Q
SBUF
TxD
CL
Phase 2 Clock
(1/2 fOSC)
Zero Detector
Mode 2
Start
÷ 16
SMOD = 1
Stop Bit
Gen.
TX Control
TX Clock
Shift
Data
T1
Send
R1
Load
SBUF
Serial
Port
Interrupt
÷2
SMOD = 0
(SMOD is
PCON.7)
÷ 16
RX Clock
Sample
RX Control
1-to-0
Transition
Detector
Shift
Start
1FFH
Bit Detector
Input Shift Register
(9 Bits)
Shift
RxD
Load
SBUF
SBUF
Read
SBUF
80C51 Internal Bus
TX
Clock
Write to SBUF
Send
Data
S1P1
Transmit
Shift
TxD
Start Bit
D0
D1
D2
D3
D4
D5
D6
D7
TB8
D0
D1
D2
D3
D4
D5
D6
D7
RB8
Stop Bit
TI
Stop Bit Gen.
÷ 16 Reset
RX
Clock
RxD
Bit Detector
Sample Times
Start
Bit
Stop Bit
Receive
Shift
RI
SU00541
Figure 17. Serial Port Mode 2
2004 Apr 20
26
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Timer 1
Overflow
80C51 Internal Bus
TB8
Write
to
SBUF
÷2
SMOD = 0
SMOD = 1
S
D
Q
SBUF
TxD
CL
Zero Detector
Start
Data
Shift
TX Control
÷ 16
TX Clock
T1
Send
R1
Load
SBUF
Serial
Port
Interrupt
÷ 16
RX Clock
Sample
RX Control
1-to-0
Transition
Detector
Shift
Start
1FFH
Bit Detector
Input Shift Register
(9 Bits)
Shift
RxD
Load
SBUF
SBUF
Read
SBUF
80C51 Internal Bus
TX
Clock
Write to SBUF
Send
Data
S1P1
Transmit
Shift
TxD
Start Bit
D0
D1
D2
D3
D4
D5
D6
D7
TB8
D0
D1
D2
D3
D4
D5
D6
D7
RB8
Stop Bit
TI
Stop Bit Gen.
RX
Clock
RxD
Bit Detector
Sample Times
÷ 16 Reset
Start
Bit
Stop Bit
Receive
Shift
RI
SU00542
Figure 18. Serial Port Mode 3
2004 Apr 20
27
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Slave 1
Enhanced Features
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 UART also fully supports multiprocessor
communication as does the standard 80C51 UART.
In a more complex system the following could be used to select
slaves 1 and 2 while excluding slave 0:
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 20.
Mode 0 is the Shift Register mode and SM2 is ignored.
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
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.
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
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:
2004 Apr 20
Slave 0
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
and 1 and exclude Slave 2 use address 1110 0100, since it is
necessary to make bit 2 = 1 to exclude slave 2.
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.
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.
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 13). 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 19.
Slave 0
SADDR =
SADEN =
Given
=
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.
1100 0000
1111 1101
1100 00X0
28
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 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
TB8
RB8
TI
RI
SCON
(98H)
SMOD1
SMOD0
–
POF
LVF
GF0
GF1
IDL
PCON
(87H)
0 : SCON.7 = SM0
1 : SCON.7 = FE
SU00044
Figure 19. 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 20. UART Multiprocessor Communication, Automatic Address Recognition
2004 Apr 20
29
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
I2C-bus Serial I/O
The I2C-bus serial port is identical to the I2C-bus serial port on the
8xC554 and 8xC652 devices.
condition or with a repeated START condition. Since a repeated
START condition is also the beginning of the next serial transfer, the
I2C-bus will not be released.
Note that in the P8xC654X2, the I2C-bus pins are alternate functions
to port pins P1.6 and P1.7. Because of this, P1.6 and P1.7 on these
parts do not have a pull-up structure as found on the 80C51; P1.6
and P1.7 have open drain outputs.
Modes of Operation: The on-chip I2C-bus logic may operate in the
following four modes:
1. Master Transmitter Mode:
Serial data output through P1.7/SDA while P1.6/SCL outputs the
serial clock. The first byte transmitted contains the slave address
of the receiving device (7 bits) and the data direction bit. In this
case the data direction bit (R/W) will be logic 0, and we say that
a “W” is transmitted. Thus the first byte transmitted is SLA+W.
Serial data is transmitted 8 bits at a time. After each byte is
transmitted, an acknowledge bit is received. START and STOP
conditions are output to indicate the beginning and the end of a
serial transfer.
The I2C-bus uses two wires (SDA and SCL) to transfer information
between devices connected to the bus. The main features of the bus
are:
– Bidirectional data transfer between masters and slaves
– Multimaster bus (no central master)
– Arbitration between simultaneously transmitting masters without
corruption of serial data on the bus
– Serial clock synchronization allows devices with different bit rates
to communicate via one serial bus
– Serial clock synchronization can be used as a handshake
mechanism to suspend and resume serial transfer
– The I2C-bus may be used for test and diagnostic purposes
2. Master Receiver Mode:
The first byte transmitted contains the slave address of the
transmitting device (7 bits) and the data direction bit. In this case
the data direction bit (R/W) will be logic 1, and we say that an “R”
is transmitted. Thus the first byte transmitted is SLA+R. Serial
data is received via P1.7/SDA while P1.6/SCL outputs the serial
clock. Serial data is received 8 bits at a time. After each byte is
received, an acknowledge bit is transmitted. START and STOP
conditions are output to indicate the beginning and end of a
serial transfer.
The output latches of P1.6 and P1.7 must be set to logic 1 in order
to enable I2C-bus.
The P8xC654X2 on-chip I2C-bus logic provides a serial interface
that meets the I2C-bus specification and supports all transfer modes
(other than the low-speed mode) from and to the I2C-bus. The
I2C-bus logic handles bytes transfer autonomously. It also keeps
track of serial transfers, and a status register (S1STA) reflects the
status of the I2C-bus.
3. Slave Receiver Mode:
Serial data and the serial clock are received through P1.7/SDA
and P1.6/SCL. After each byte is received, an acknowledge bit is
transmitted. START and STOP conditions are recognized as the
beginning and end of a serial transfer. Address recognition is
performed by hardware after reception of the slave address and
direction bit.
The CPU interfaces to the I2C-bus logic via the following four special
function registers: S1CON (I2C-bus control register), S1STA
(I2C-bus status register), S1DAT (I2C-bus data register), and
S1ADR (I2C-bus slave address register). The I2C-bus logic
interfaces to the external I2C-bus via two port 1 pins: P1.6/SCL
(serial clock line) and P1.7/SDA (serial data line).
4. Slave Transmitter Mode:
A typical I2C-bus configuration is shown in Figure 21, and Figure 22
shows how a data transfer is accomplished on the bus. Depending
on the state of the direction bit (R/W), two types of data transfers are
possible on the I2C-bus:
1. Data transfer from a master transmitter to a slave receiver. The
first byte transmitted by the master is the slave address. Next
follows a number of data bytes. The slave returns an
acknowledge bit after each received byte.
The first byte is received and handled as in the slave receiver
mode. However, in this mode, the direction bit will indicate that
the transfer direction is reversed. Serial data is transmitted via
P1.7/SDA while the serial clock is input through P1.6/SCL.
START and STOP conditions are recognized as the beginning
and end of a serial transfer.
In a given application, I2C-bus may operate as a master and as a
slave. In the slave mode, the I2C-bus hardware looks for its own
slave address and the general call address. If one of these
addresses is detected, an interrupt is requested. When the
microcontroller wishes to become the bus master, the hardware
waits until the bus is free before the master mode is entered so that
a possible slave action is not interrupted. If bus arbitration is lost in
the master mode, the I2C-bus switches to the slave mode
immediately and can detect its own slave address in the same serial
transfer.
2. Data transfer from a slave transmitter to a master receiver. The
first byte (the slave address) is transmitted by the master. The
slave then returns an acknowledge bit. Next follows the data
bytes transmitted by the slave to the master. The master returns
an acknowledge bit after all received bytes other than the last
byte. At the end of the last received byte, a “not acknowledge” is
returned.
The master device generates all of the serial clock pulses and the
START and STOP conditions. A transfer is ended with a STOP
2004 Apr 20
30
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
VDD
RP
RP
SDA
I2C-bus
SCL
P1.7/SDA
P1.6/SCL
OTHER DEVICE WITH
I2C-BUS INTERFACE
P8xC654X2
OTHER DEVICE WITH
I2C-BUS INTERFACE
SU01734
Figure 21. Typical I2C-bus configuration
STOP
CONDITION
SDA
REPEATED
START
CONDITION
MSB
SLAVE ADDRESS
R/W
DIRECTION
BIT
ACKNOWLEDGMENT
SIGNAL FROM RECEIVER
ACKNOWLEDGMENT
SIGNAL FROM RECEIVER
SCL
1
S
2
7
8
9
ACK
CLOCK LINE HELD LOW WHILE
INTERRUPTS ARE SERVICED
1
2
9
ACK
P/S
REPEATED IF MORE BYTES
ARE TRANSFERRED
START
CONDITION
SU00965
Figure 22. Data Transfer on the
I2C-bus Implementation and Operation: Figure 23 shows how the
on-chip I2C-bus interface is implemented, and the following text
describes the individual blocks.
I2C-bus
when programmed as a slave transmitter or receiver. The LSB (GC)
is used to enable general call address (00H) recognition.
COMPARATOR
The comparator compares the received 7-bit slave address with its
own slave address (7 most significant bits in S1ADR). It also
compares the first received 8-bit byte with the general call address
(00H). If an equality is found, the appropriate status bits are set and
an interrupt is requested.
INPUT FILTERS AND OUTPUT STAGES
The input filters have I2C-bus compatible input levels. If the input
voltage is less than 1.5 V, the input logic level is interpreted as 0; if
the input voltage is greater than 3.0 V, the input logic level is
interpreted as 1. Input signals are synchronized with the internal
clock (fOSC/4), and spikes shorter than three oscillator periods are
filtered out.
SHIFT REGISTER, S1DAT
This 8-bit special function register contains a byte of serial data to
be transmitted or a byte which has just been received. Data in
S1DAT is always shifted from right to left; the first bit to be
transmitted is the MSB (bit 7) and, after a byte has been received,
the first bit of received data is located at the MSB of S1DAT. While
data is being shifted out, data on the bus is simultaneously being
shifted in; S1DAT always contains the last byte present on the bus.
Thus, in the event of lost arbitration, the transition from master
transmitter to slave receiver is made with the correct data in S1DAT.
The output stages consist of open drain transistors that can sink
3mA at VOUT < 0.4 V. These open drain outputs do not have
clamping diodes to VDD. Thus, if the device is connected to the
I2C-bus and VDD is switched off, the I2C-bus is not affected.
ADDRESS REGISTER, S1ADR
This 8-bit special function register may be loaded with the 7-bit slave
address (7 most significant bits) to which the I2C-bus will respond
2004 Apr 20
3–8
31
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Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
8
S1ADR
ADDRESS REGISTER
P1.7
COMPARATOR
INPUT
FILTER
P1.7/SDA
S1DAT
OUTPUT
STAGE
SHIFT REGISTER
ACK
ARBITRATION &
SYNC LOGIC
INPUT
FILTER
P1.6/SCL
INTERNAL BUS
8
TIMING
&
CONTROL
LOGIC
fOSC/4
SERIAL CLOCK
GENERATOR
OUTPUT
STAGE
INTERRUPT
TIMER 1
OVERFLOW
S1CON
CONTROL REGISTER
P1.6
8
STATUS BITS
STATUS
DECODER
S1STA
STATUS REGISTER
8
su00966
Figure 23.
2004 Apr 20
I2C-bus
Serial Interface Block Diagram
32
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
The synchronization logic will synchronize the serial clock generator
with the clock pulses on the SCL line from another device. If two or
more master devices generate clock pulses, the “mark” duration is
determined by the device that generates the shortest “marks,” and
the “space” duration is determined by the device that generates the
longest “spaces.” Figure 25 shows the synchronization procedure.
ARBITRATION AND SYNCHRONIZATION LOGIC
In the master transmitter mode, the arbitration logic checks that
every transmitted logic 1 actually appears as a logic 1 on the
I2C-bus. If another device on the bus overrules a logic 1 and pulls
the SDA line LOW, arbitration is lost, and the I2C-bus immediately
changes from master transmitter to slave receiver. The I2C-bus will
continue to output clock pulses (on SCL) until transmission of the
current serial byte is complete.
A slave may stretch the space duration to slow down the bus
master. The space duration may also be stretched for handshaking
purposes. This can be done after each bit or after a complete byte
transfer. The I2C-bus will stretch the SCL space duration after a byte
has been transmitted or received and the acknowledge bit has been
transferred. The serial interrupt flag (SI) is set, and the stretching
continues until the serial interrupt flag is cleared.
Arbitration may also be lost in the master receiver mode. Loss of
arbitration in this mode can only occur while the I2C-bus is returning
a “not acknowledge: (logic 1) to the bus. Arbitration is lost when
another device on the bus pulls this signal LOW. Since this can
occur only at the end of a serial byte, the I2C-bus generates no
further clock pulses. Figure 24 shows the arbitration procedure.
(3)
(1)
(1)
(2)
SDA
SCL
2
1
3
4
8
9
ACK
1. Another device transmits identical serial data.
2. Another device overrules a logic 1 (dotted line) transmitted by SIO1 (master) by pulling the SDA line low. Arbitration is
lost, and SIO1 enters the slave receiver mode.
3. SIO1 is in the slave receiver mode but still generates clock pulses until the current byte has been transmitted. SIO1 will
not generate clock pulses for the next byte. Data on SDA originates from the new master once it has won arbitration.
SU00967
Figure 24. Arbitration Procedure
SDA
(1)
(3)
(1)
SCL
(2)
MARK
DURATION
SPACE DURATION
1. Another service pulls the SCL line low before the SIO1 “mark” duration is complete. The serial clock generator is immediately
reset and commences with the “space” duration by pulling SCL low.
2. Another device still pulls the SCL line low after SIO1 releases SCL. The serial clock generator is forced into the wait state
until the SCL line is released.
3. The SCL line is released, and the serial clock generator commences with the mark duration.
SU00968
Figure 25. Serial Clock Synchronization
2004 Apr 20
33
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
not in the process of shifting a byte. This occurs when the I2C-bus is
in a defined state and the serial interrupt flag is set. Data in S1DAT
remains stable as long as SI is set. Data in S1DAT is always shifted
from right to left: the first bit to be transmitted is the MSB (bit 7), and,
after a byte has been received, the first bit of received data is
located at the MSB of S1DAT. While data is being shifted out, data
on the bus is simultaneously being shifted in; S1DAT always
contains the last data byte present on the bus. Thus, in the event of
lost arbitration, the transition from master transmitter to slave
receiver is made with the correct data in S1DAT.
SERIAL CLOCK GENERATOR
This programmable clock pulse generator provides the SCL clock
pulses when the I2C-bus is in the master transmitter or master
receiver mode. It is switched off when the I2C-bus is in a slave
mode. In standard speed mode, the programmable output clock
frequencies are: fOSC/120, fOSC/9600, and the Timer 1 overflow rate
divided by eight. The output clock pulses have a 50 % duty cycle
unless the clock generator is synchronized with other SCL clock
sources as described above.
TIMING AND CONTROL
The timing and control logic generates the timing and control signals
for serial byte handling. This logic block provides the shift pulses for
S1DAT, enables the comparator, generates and detects start and
stop conditions, receives and transmits acknowledge bits, controls
the master and slave modes, contains interrupt request logic, and
monitors the I2C-bus status.
7
S1DAT
(DAH)
S1ADR
(DBH)
X
X
X
3
2
1
0
X
X
X
X
GC
SD3 SD2
1
0
SD1 SD0
shift direction
The Control Register, S1CON: The CPU can read from and write
to this 8-bit, directly addressable SFR. Two bits are affected by the
I2C hardware: the SI bit is set when a serial interrupt is requested,
and the STO bit is cleared when a STOP condition is present on the
I2C-bus. The STO bit is also cleared when ENS1 = 0.
S1CON
(D8H)
7
6
5
4
3
2
1
0
CR2
ENS1
STA
STO
SI
AA
CR1
CR0
ENS1, THE I2C ENABLE BIT
ENS1 = 0: When ENS1 is logic 0, the SDA and SCL outputs are in a
high impedance state. SDA and SCL input signals are ignored, I2C
is in the “not addressed” slave state, and the STO bit in S1CON is
forced to 0. No other bits are affected. P1.6 and P1.7 may be used
as open drain I/O ports.
own slave address
The most significant bit corresponds to the first bit received from the
I2C-bus after a start condition. A logic 1 in S1ADR corresponds to a
HIGH level on the I2C-bus, and a logic 0 corresponds to a LOW
level on the bus.
ENS1 = 1: When ENS1 is “1”, I2C is enabled. The P1.6 and P1.7
port latches must be set to logic 1.
ENS1 should not be used to temporarily release I2C from the
I2C-bus since, when ENS1 is reset, the I2C-bus status is lost. The
AA flag should be used instead (see description of the AA flag in the
following text).
The Data Register, S1DAT: S1DAT contains a byte of serial data to
be transmitted or a byte which has just been received. The CPU can
read from and write to this 8-bit, directly addressable SFR while it is
2004 Apr 20
SD4
2
When the CPU writes to S1DAT, BSD7 is loaded with the content of
S1DAT.7, which is the first bit to be transmitted to the SDA line (see
Figure 27). After nine serial clock pulses, the eight bits in S1DAT will
have been transmitted to the SDA line, and the acknowledge bit will
be present in ACK. Note that the eight transmitted bits are shifted
back into S1DAT.
The Address Register, S1ADR: The CPU can read from and write
to this 8-bit, directly addressable SFR. S1ADR is not affected by the
the I2C-bus hardware. The contents of this register are irrelevant
when the I2C-bus is in a master mode. In the slave modes, the
seven most significant bits must be loaded with the microcontroller’s
own slave address, and, if the least significant bit is set, the general
call address (00H) is recognized; otherwise it is ignored.
4
SD5
3
S1DAT and the ACK flag form a 9-bit shift register which shifts in or
shifts out an 8-bit byte, followed by an acknowledge bit. The ACK
flag is controlled by the I2C-bus hardware and cannot be accessed
by the CPU. Serial data is shifted through the ACK flag into S1DAT
on the rising edges of serial clock pulses on the SCL line. When a
byte has been shifted into S1DAT, the serial data is available in
S1DAT, and the acknowledge bit is returned by the control logic
during the ninth clock pulse. Serial data is shifted out from S1DAT
via a buffer (BSD7) on the falling edges of clock pulses on the SCL
line.
The Four I2C-bus Special Function Registers: The
microcontroller interfaces to the I2C-bus via four special function
registers. These four SFRs (S1ADR, S1DAT, S1CON, and S1STA)
are described individually in the following sections.
5
4
Eight bits to be transmitted or just received. A logic 1 in S1DAT
corresponds to a HIGH level on the I2C-bus, and a logic 0
corresponds to a LOW level on the bus. Serial data shifts through
S1DAT from right to left. Figure 26 shows how data in S1DAT is
serially transferred to and from the SDA line.
STATUS DECODER AND STATUS REGISTER
The status decoder takes all of the internal status bits and
compresses them into a 5-bit code. This code is unique for each
I2C-bus status. The 5-bit code may be used to generate vector
addresses for fast processing of the various service routines. Each
service routine processes a particular bus status. There are 26
possible bus states if all four modes of the I2C-bus are used. The
5-bit status code is latched into the five most significant bits of the
status register when the serial interrupt flag is set (by hardware) and
remains stable until the interrupt flag is cleared by software. The
three least significant bits of the status register are always zero. If
the status code is used as a vector to service routines, then the
routines are displaced by eight address locations. Eight bytes of
code is sufficient for most of the service routines (see the software
example in this section).
6
SD7 SD6
5
SD7 - SD0:
CONTROL REGISTER, S1CON
This 7-bit special function register is used by the microcontroller to
control the following I2C-bus functions: start and restart of a serial
transfer, termination of a serial transfer, bit rate, address recognition,
and acknowledgment.
7
6
34
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
INTERNAL BUS
SDA
8
BSD7
S1DAT
ACK
SCL
SHIFT PULSES
SU00969
Figure 26. Serial Input/Output Configuration
SDA
D7
D6
D5
D4
D3
D2
D1
D0
A
SCL
SHIFT ACK & S1DAT
SHIFT IN
ACK
S1DAT
(1)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
A
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(1)
SHIFT BSD7
SHIFT OUT
BSD7
D7
D6
D5
D4
D3
D2
D1
D0
(3)
LOADED BY THE CPU
(1) Valid data in S1DAT
(2) Shifting data in S1DAT and ACK
(3) High level on SDA
SU00970
Figure 27. Shift-in and Shift-out Timing
In the following text, it is assumed that ENS1 = 1.
STA = 0: When the STA bit is reset, no START condition or repeated
START condition will be generated.
STA, THE START FLAG
STA = 1: When the STA bit is set to enter a master mode, the I2C
hardware checks the status of the I2C-bus and generates a START
condition if the bus is free. If the bus is not free, then I2C waits for a
STOP condition (which will free the bus) and generates a START
condition after a delay of a half clock period of the internal serial
clock generator.
STO, THE STOP FLAG
STO = 1: When the STO bit is set while I2C is in a master mode, a
STOP condition is transmitted to the I2C-bus. When the STOP
condition is detected on the bus, the I2C hardware clears the STO
flag. In a slave mode, the STO flag may be set to recover from an
error condition. In this case, no STOP condition is transmitted to the
I2C-bus. However, the I2C hardware behaves as if a STOP condition
has been received and switches to the defined “not addressed”
slave receiver mode. The STO flag is automatically cleared by
hardware.
If STA is set while I2C is already in a master mode and one or more
bytes are transmitted or received, I2C transmits a repeated START
condition. STA may be set at any time. STA may also be set when
I2C is an addressed slave.
2004 Apr 20
35
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
When I2C is in the not addressed slave mode, its own slave address
and the general call address are ignored. Consequently, no
acknowledge is returned, and a serial interrupt is not requested.
Thus, I2C can be temporarily released from the I2C-bus while the
bus status is monitored. While I2C is released from the bus, START
and STOP conditions are detected, and serial data is shifted in.
Address recognition can be resumed at any time by setting the AA
flag. If the AA flag is set when the part’s own slave address or the
general call address has been partly received, the address will be
recognized at the end of the byte transmission.
If the STA and STO bits are both set, the a STOP condition is
transmitted to the I2C-bus if I2C is in a master mode (in a slave
mode, I2C generates an internal STOP condition which is not
transmitted). I2C then transmits a START condition.
STO = 0: When the STO bit is reset, no STOP condition will be
generated.
SI, THE SERIAL INTERRUPT FLAG
SI = 1: When the SI flag is set, then, if the EA and ES1 (interrupt
enable register) bits are also set, a serial interrupt is requested. SI is
set by hardware when one of 25 of the 26 possible I2C states is
entered. The only state that does not cause SI to be set is state
F8H, which indicates that no relevant state information is available.
CR0, CR1, AND CR2, THE CLOCK RATE BITS
These three bits determine the serial clock frequency when I2C is in
a master mode. The various serial rates are shown in Table 7.
While SI is set, the LOW period of the serial clock on the SCL line is
stretched, and the serial transfer is suspended. A HIGH level on the
SCL line is unaffected by the serial interrupt flag. SI must be reset
by software.
If the I2C block is to be used in fast mode, bit 3 in AUXR must be
set. The user can read but cannot write (write once) to AUXR after
setup.
7
SI = 0: When the SI flag is reset, no serial interrupt is requested, and
there is no stretching of the serial clock on the SCL line.
AUXR
(8EH)
AA, THE ASSERT ACKNOWLEDGE FLAG
AA = 1: If the AA flag is set, an acknowledge (low level to SDA) will
be returned during the acknowledge clock pulse on the SCL line
when:
– The “own slave address” has been received
– The general call address has been received while the general call
bit (GC) in S1ADR is set
– A data byte has been received while I2C is in the master receiver
mode
– A data byte has been received while I2C is in the addressed slave
receiver mode
–
5
–
4
3
2
1
0
–
FAST/
STD
I2C
–
–
A0
A 12.5kHz bit rate may be used by devices that interface to the
I2C-bus via standard I/O port lines which are software driven and
slow. 100kHz is usually the maximum bit rate and can be derived
from a 16 MHz, 12 MHz, or a 6 MHz oscillator. A variable bit rate
(0.5kHz to 62.5kHz) may also be used if Timer 1 is not required for
any other purpose while I2C is in a master mode.
The frequencies shown in Table 7 are unimportant when I2C is in a
slave mode. In the slave modes, I2C will automatically synchronize
with any clock frequency up to 100kHz.
AA = 0: if the AA flag is reset, a not acknowledge (HIGH level to
SDA) will be returned during the acknowledge clock pulse on SCL
when:
– A data has been received while I2C is in the master receiver mode
– A data byte has been received while I2C is in the addressed slave
receiver mode
The Status Register, S1STA: S1STA is an 8-bit read-only special
function register. The three least significant bits are always zero.
The five most significant bits contain the status code. There are 26
possible status codes. When S1STA contains F8H, no relevant state
information is available and no serial interrupt is requested. All other
S1STA values correspond to defined I2C states. When each of
these states is entered, a serial interrupt is requested (SI = 1). A
valid status code is present in S1STA one machine cycle after SI is
set by hardware and is still present one machine cycle after SI has
been reset by software.
When I2C is in the addressed slave transmitter mode, state C8H will
be entered after the last serial is transmitted (see Figure 31). When
SI is cleared, I2C leaves state C8H, enters the not addressed slave
receiver mode, and the SDA line remains at a HIGH level. In state
C8H, the AA flag can be set again for future address recognition.
2004 Apr 20
–
6
36
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Table 7.
Serial Clock Rates
6 clock mode
BIT FREQUENCY (kHz) AT fosc
fosc DIVIDED BY
CR2
CR1
CR0
3MHz
6MHz
8MHz
12MHz
15MHz
0
0
0
23
47
62.5
94
117
128
0
0
1
27
54
71
107
134
112
0
1
0
31
63
83.3
125
156
96
0
1
1
37
75
100
150
188
80
1
0
0
6.25
12.5
17
25
31
480
1
0
1
50
100
133
200
250
60
1
1
0
100
200
267
400
500
30
1
1
1
0.24<62.5
0.49 < 62.5
0.65 < 55.6
0.98 < 50.0
1.22 < 52.1
48 × (256– (reload value Timer1))
0 < 255
0 < 254
0 < 253
0 < 251
0 < 250
Reload value Timer 1 in Mode 2.
12 clock mode
BIT FREQUENCY (kHz) AT fosc
fosc DIVIDED BY
CR2
CR1
CR0
6MHz
12MHz
16MHz
24MHz
30MHz
0
0
0
23
47
62.5
94
117
256
0
0
1
27
54
71
107
134
224
0
1
0
31
63
83.3
125
156
192
0
1
1
37
75
100
150
188
160
1
0
0
6.25
12.5
17
25
31
960
1
0
1
50
100
133
200
250
120
1
1
0
100
200
267
400
500
60
1
1
1
0.24<62.5
0.49 < 62.5
0.65 < 55.6
0.98 < 50.0
1.22 < 52.1
96 × (256 –(reload value Timer1))
0 < 255
0 < 254
0 < 253
0 < 251
0 < 250
Reload value Timer 1 in Mode 2.
NOTES:
1. These frequencies exceed the upper limit of 100kHz of the I2C-bus specification and cannot be used in an I2C-bus application.
2. At fosc = 24 MHz/30 MHz the maximum I2C-bus rate of 100kHz cannot be realized due to the fixed divider rates.
Table 8.
Selection of I2C-bus bit rate (Fast mode)
BIT FREQUENCY (kHz) AT fosc
CR2
CR1
CR0
12 MHz
16 MHz
1
0
0
50
66.7
1
0
1
3.75
5
1
1
0
75
100
1
1
1
100
0
266.71
0
0
0
2001
0
0
1
7.5
10
4001
–
0
1
0
3001
0
1
1
4001
NOTES:
1. These bit rates are for “fast-mode” I2C-bus applications and cannot be used for bit rates up to 100 kbit/sec.
2. Serial status register S1STA is a read only register.
2004 Apr 20
37
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
More Information on I2C Operating Modes: The four operating
modes are:
– Master Transmitter
– Master Receiver
– Slave Receiver
– Slave Transmitter
may switch to the master receiver mode by loading S1DAT with
SLA+R).
Master Receiver Mode: In the master receiver mode, a number of
data bytes are received from a slave transmitter (see Figure 29).
The transfer is initialized as in the master transmitter mode. When
the start condition has been transmitted, the interrupt service routine
must load S1DAT with the 7-bit slave address and the data direction
bit (SLA+R). The SI bit in S1CON must then be cleared before the
serial transfer can continue.
Data transfers in each mode of operation are shown in Figures
28–31. These figures contain the following abbreviations:
Abbreviation
S
SLA
R
W
A
A
Data
P
Explanation
Start condition
7-bit slave address
Read bit (HIGH level at SDA)
Write bit (low level at SDA)
Acknowledge bit (low level at SDA)
Not acknowledge bit (HIGH level at SDA)
8-bit data byte
Stop condition
When the slave address and the data direction bit have been
transmitted and an acknowledgment bit has been received, the
serial interrupt flag (SI) is set again, and a number of status codes in
S1STA are possible. These are 40H, 48H, or 38H for the master
mode and also 68H, 78H, or B0H if the slave mode was enabled
(AA = logic 1). The appropriate action to be taken for each of these
status codes is detailed in Table 10. ENS1, CR1, and CR0 are not
affected by the serial transfer and are not referred to in Table 10.
After a repeated start condition (state 10H), I2C may switch to the
master transmitter mode by loading S1DAT with SLA+W.
In Figures 28-31, circles are used to indicate when the serial
interrupt flag is set. The numbers in the circles show the status code
held in the S1STA register. At these points, a service routine must
be executed to continue or complete the serial transfer. These
service routines are not critical since the serial transfer is suspended
until the serial interrupt flag is cleared by software.
Slave Receiver Mode: In the slave receiver mode, a number of
data bytes are received from a master transmitter (see Figure 30).
To initiate the slave receiver mode, S1ADR and S1CON must be
loaded as follows:
When a serial interrupt routine is entered, the status code in S1STA
is used to branch to the appropriate service routine. For each status
code, the required software action and details of the following serial
transfer are given in Tables 9-13.
AUXR#
S1CON
(D8H)
CR2
bit
rate
6
ENS1
1
5
4
3
2
1
0
STA
STO
SI
AA
CR1
CR0
0
0
0
X
7
S1CON
(D8H)
bit rate
–
–
–
–
Fast/
Std
I2C
–
–
AO
CR2
X
6
ENS1
1
5
4
3
2
1
0
STA
0
STO
SI
AA
CR1
CR0
0
0
1
X
X
CR0, CR1, and CR2 do not affect I2C in the slave mode. ENS1 must
be set to logic 1 to enable I2C. The AA bit must be set to enable I2C
to acknowledge its own slave address or the general call address.
STA, STO, and SI must be reset.
CR0, CR1, and CR2 define the serial bit rate. ENS1 must be set to
logic 1 to enable I2C. If the AA bit is reset, I2C will not acknowledge
its own slave address or the general call address in the event of
another device becoming master of the bus. In other words, if AA is
reset, SIO0 cannot enter a slave mode. STA, STO, and SI must be
reset.
When S1ADR and S1CON have been initialized, I2C waits until it is
addressed by its own slave address followed by the data direction
bit which must be logic 0 (W) for I2C to operate in the slave receiver
mode. After its own slave address and the W bit have been
received, the serial interrupt flag (I) is set and a valid status code
can be read from S1STA. This status code is used to vector to an
interrupt service routine, and the appropriate action to be taken for
each of these status codes is detailed in Table 11. The slave
receiver mode may also be entered if arbitration is lost while I2C is
in the master mode (see status 68H and 78H).
The master transmitter mode may now be entered by setting the
STA bit using the SETB instruction. The I2C logic will now test the
I2C-bus and generate a start condition as soon as the bus becomes
free. When a START condition is transmitted, the serial interrupt flag
(SI) is set, and the status code in the status register (S1STA) will be
08H. This status code must be used to vector to an interrupt service
routine that loads S1DAT with the slave address and the data
direction bit (SLA+W). The SI bit in S1CON must then be reset
before the serial transfer can continue.
If the AA bit is reset during a transfer, I2C will return a not
acknowledge (logic 1) to SDA after the next received data byte.
While AA is reset, I2C does not respond to its own slave address or
a general call address. However, the I2C-bus is still monitored and
address recognition may be resumed at any time by setting AA. This
means that the AA bit may be used to temporarily isolate I2C from
the I2C-bus.
When the slave address and the direction bit have been transmitted
and an acknowledgment bit has been received, the serial interrupt
flag (SI) is set again, and a number of status codes in S1STA are
possible. There are 18H, 20H, or 38H for the master mode and also
68H, 78H, or B0H if the slave mode was enabled (AA = logic 1). The
appropriate action to be taken for each of these status codes is
detailed in Table 9. After a repeated start condition (state 10H). I2C
2004 Apr 20
8EH
The upper 7 bits are the address to which I2C will respond when
addressed by a master. If the LSB (GC) is set, I2C will respond to
the general call address (00H); otherwise it ignores the general call
address.
Master Transmitter Mode: In the master transmitter mode, a
number of data bytes are transmitted to a slave receiver (see
Figure 28). Before the master transmitter mode can be entered,
S1CON must be initialized as follows:
7
Auxiliary
38
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
MT
SUCCESSFUL TRANSMISSION
TO A SLAVE RECEIVER
ÇÇÇÇÇÇÇÇ ÇÇÇ
ÇÇÇ ÇÇÇ
ÇÇÇÇÇÇÇÇ ÇÇÇ
ÇÇÇ ÇÇÇ
ÇÇÇÇÇÇÇ
ÇÇÇÇÇÇÇ
ÇÇÇÇÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
S
SLA
W
A
08H
DATA
A
P
28H
18H
NEXT TRANSFER STARTED WITH A REPEATED START CONDITION
S
SLA
W
10H
NOT ACKNOWLEDGE RECEIVED AFTER THE SLAVE ADDRESS
A
P
R
20H
NOT ACKNOWLEDGE RECEIVED AFTER A DATA BYTE
A
P
TO MST/REC MODE
ENTRY = MR
30H
ARBITRATION LOST IN SLAVE ADDRESS OR DATA BYTE
A or A
OTHER MST
CONTINUES
38H
ARBITRATION LOST AND ADDRESSED AS SLAVE
ÇÇÇÇ
ÇÇÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇ
ÇÇÇ
ÇÇ
Data
n
A
A
68H
A or A
OTHER MST
CONTINUES
38H
OTHER MST
CONTINUES
78H
80H
TO CORRESPONDING
STATES IN SLAVE MODE
FROM MASTER TO SLAVE
FROM SLAVE TO MASTER
ANY NUMBER OF DATA BYTES AND THEIR ASSOCIATED ACKNOWLEDGE BITS
THIS NUMBER (CONTAINED IN S1STA) CORRESPONDS TO A DEFINED STATE OF THE I2C BUS. SEE TABLE 9.
SU00971
Figure 28. Format and States in the Master Transmitter Mode
2004 Apr 20
39
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
MR
ÇÇÇÇÇÇÇÇ
ÇÇÇÇÇÇÇÇ
SUCCESSFUL RECEPTION
FROM A SLAVE TRANSMITTER
S
SLA
08H
R
ÇÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇÇÇÇÇ
ÇÇÇÇÇÇÇ
ÇÇÇÇÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
A
DATA
DATA
A
50H
40H
NEXT TRANSFER STARTED WITH A
REPEATED START CONDITION
A
P
58H
S
SLA
R
10H
NOT ACKNOWLEDGE RECEIVED
AFTER THE SLAVE ADDRESS
A
P
W
48H
ARBITRATION LOST IN SLAVE ADDRESS
OR ACKNOWLEDGE BIT
A or A
OTHER MST
CONTINUES
ÇÇÇ
ÇÇÇ
ÇÇÇ
A
38H
ARBITRATION LOST AND ADDRESSED AS SLAVE
A
68H
ÇÇÇÇ
ÇÇÇÇ
ÇÇÇÇ
ÇÇ
ÇÇÇÇ
ÇÇ
TO MST/TRX MODE
ENTRY = MT
OTHER MST
CONTINUES
38H
OTHER MST
CONTINUES
78H
80H
TO CORRESPONDING
STATES IN SLAVE MODE
FROM MASTER TO SLAVE
FROM SLAVE TO MASTER
DATA
n
A
ANY NUMBER OF DATA BYTES AND THEIR ASSOCIATED ACKNOWLEDGE BITS
THIS NUMBER (CONTAINED IN S1STA) CORRESPONDS TO A DEFINED STATE OF THE I2C-BUS. SEE TABLE 10.
SU00972
Figure 29. Format and States in the Master Receiver Mode
2004 Apr 20
40
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
RECEPTION OF THE OWN SLAVE ADDRESS
AND ONE OR MORE DATA BYTES
ALL ARE ACKNOWLEDGED.
ÇÇÇÇÇÇÇ ÇÇÇ
ÇÇÇÇ ÇÇÇ ÇÇÇ
ÇÇÇÇÇÇÇ ÇÇÇ
ÇÇÇÇ ÇÇÇ ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
S
SLA
W
A
DATA
DATA
SLA
80H
60H
LAST DATA BYTE RECEIVED IS
NOT ACKNOWLEDGED
A
A
P or S
80H
A0H
A
P or S
88H
ARBITRATION LOST AS MST AND
ADDRESSED AS SLAVE
A
68H
RECEPTION OF THE GENERAL CALL ADDRESS
AND ONE OR MORE DATA BYTES
ÇÇÇÇÇ ÇÇÇ
ÇÇÇÇ ÇÇÇ ÇÇÇ
ÇÇÇÇÇ ÇÇÇ
ÇÇÇÇ ÇÇÇ ÇÇÇ
ÇÇÇÇÇ ÇÇÇ
ÇÇÇÇ ÇÇÇ ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
GENERAL
CALL
A
DATA
70H
LAST DATA BYTE IS NOT ACKNOWLEDGED
A
90H
DATA
A
90H
A
P or S
A0H
P or S
98H
ARBITRATION LOST AS MST AND ADDRESSED AS SLAVE BY GENERAL CALL
ÇÇÇÇ
ÇÇÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇ
ÇÇÇ
ÇÇ
Data
n
A
78H
FROM MASTER TO SLAVE
FROM SLAVE TO MASTER
A
ANY NUMBER OF DATA BYTES AND THEIR ASSOCIATED ACKNOWLEDGE BITS
THIS NUMBER (CONTAINED IN S1STA) CORRESPONDS TO A DEFINED STATE OF THE I2C BUS. SEE TABLE 11.
SU00973
Figure 30. Format and States in the Slave Receiver Mode
2004 Apr 20
41
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
ÇÇÇÇÇÇÇÇ
ÇÇÇÇÇÇÇÇ
ÇÇÇÇÇÇÇÇ
RECEPTION OF THE
OWN SLAVE ADDRESS
AND TRANSMISSION
OF ONE OR MORE
DATA BYTES
S
SLA
R
A
DATA
ÇÇÇÇ
ÇÇÇÇ
ÇÇÇÇ
ÇÇÇÇ
ÇÇ
ÇÇ
FROM MASTER TO SLAVE
B0H
A
n
A
A
P or S
C0H
ARBITRATION LOST AS MST
AND ADDRESSED AS SLAVE
LAST DATA BYTE TRANSMITTED.
SWITCHED TO NOT ADDRESSED
SLAVE (AA BIT IN S1CON = “0”
FROM SLAVE TO MASTER
DATA
DATA
B8H
A8H
A
ÇÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
A
All “1”s
ÇÇÇ
ÇÇÇ
ÇÇÇ
P or S
C8H
ANY NUMBER OF DATA BYTES AND THEIR ASSOCIATED ACKNOWLEDGE BITS
THIS NUMBER (CONTAINED IN S1STA) CORRESPONDS TO A DEFINED STATE OF THE I2C BUS. SEE TABLE 12.
SU00974
Figure 31. Format and States of the Slave Transmitter Mode
2004 Apr 20
42
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Table 9.
STATUS
CODE
(S1STA)
Master Transmitter Mode
STATUS OF THE
I2C BUS AND
HARDWARE
APPLICATION SOFTWARE RESPONSE
NEXT ACTION TAKEN BY AND I2C
HARDWARE
TO S1CON
TO/FROM S1DAT
STA
STO
SI
AA
08H
A START condition has
been transmitted
Load SLA+W
X
0
0
X
SLA+W will be transmitted;
ACK bit will be received
10H
A repeated START
condition
diti has
h been
b
transmitted
Load SLA+W or
Load SLA+R
X
X
0
0
0
0
X
X
As above
SLA+W will be transmitted;
I2C will be switched to MST/REC mode
18H
SLA+W has been
transmitted; ACK has
b
been
received
i d
Load data byte or
0
0
0
X
no S1DAT action or
no S1DAT action or
1
0
0
1
0
0
X
X
no S1DAT action
1
1
0
X
Data byte will be transmitted;
ACK bit will be received
Repeated START will be transmitted;
STOP condition will be transmitted;
STO flag will be reset
STOP condition followed by a
START condition will be transmitted;
STO flag will be reset
Load data byte or
0
0
0
X
no S1DAT action or
no S1DAT action or
1
0
0
1
0
0
X
X
no S1DAT action
1
1
0
X
Load data byte or
0
0
0
X
no S1DAT action or
no S1DAT action or
1
0
0
1
0
0
X
X
no S1DAT action
1
1
0
X
Load data byte or
0
0
0
X
no S1DAT action or
no S1DAT action or
1
0
0
1
0
0
X
X
no S1DAT action
1
1
0
X
No S1DAT action or
0
0
0
X
No S1DAT action
1
0
0
X
20H
28H
30H
38H
2004 Apr 20
SLA+W has been
transmitted; NOT ACK
h been
b
i d
has
received
Data byte in S1DAT has
been transmitted; ACK
h been
b
i d
has
received
Data byte in S1DAT has
been transmitted; NOT
h been
b
i d
ACK has
received
Arbitration lost in
SLA+R/W or
D
Data
b
bytes
43
Data byte will be transmitted;
ACK bit will be received
Repeated START will be transmitted;
STOP condition will be transmitted;
STO flag will be reset
STOP condition followed by a
START condition will be transmitted;
STO flag will be reset
Data byte will be transmitted;
ACK bit will be received
Repeated START will be transmitted;
STOP condition will be transmitted;
STO flag will be reset
STOP condition followed by a
START condition will be transmitted;
STO flag will be reset
Data byte will be transmitted;
ACK bit will be received
Repeated START will be transmitted;
STOP condition will be transmitted;
STO flag will be reset
STOP condition followed by a
START condition will be transmitted;
STO flag will be reset
I2C-bus will be released;
not addressed slave will be entered
A START condition will be transmitted when the
bus becomes free
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Table 10.
STATUS
CODE
(S1STA)
Master Receiver Mode
STATUS OF THE
I2C-BUS AND
HARDWARE
APPLICATION SOFTWARE RESPONSE
NEXT ACTION TAKEN BY I2C HARDWARE
TO S1CON
TO/FROM S1DAT
STA
STO
SI
AA
08H
A START condition has
been transmitted
Load SLA+R
X
0
0
X
SLA+R will be transmitted;
ACK bit will be received
10H
A repeated START
condition
diti h
has b
been
transmitted
Load SLA+R or
Load SLA+W
X
X
0
0
0
0
X
X
As above
SLA+W will be transmitted;
I2C will be switched to MST/TRX mode
38H
Arbitration lost in
NOT ACK bit
No S1DAT action or
0
0
0
X
No S1DAT action
1
0
0
X
I2C-bus will be released;
I2C will enter a slave mode
A START condition will be transmitted when the
bus becomes free
SLA+R has been
transmitted; ACK has
b
i d
been received
No S1DAT action or
0
0
0
0
no S1DAT action
0
0
0
1
SLA+R has been
t
transmitted;
itt d NOT ACK
has been received
No S1DAT action or
no S1DAT action or
1
0
0
1
0
0
X
X
no S1DAT action
1
1
0
X
Data byte has been
received; ACK has been
d
returned
Read data byte or
0
0
0
0
read data byte
0
0
0
1
Data byte has been
received;
i d NOT ACK h
has
been returned
Read data byte or
read data byte or
1
0
0
1
0
0
X
X
read data byte
1
1
0
X
40H
48H
50H
58H
2004 Apr 20
44
Data byte will be received;
NOT ACK bit will be returned
Data byte will be received;
ACK bit will be returned
Repeated START condition will be transmitted
STOP condition will be transmitted;
STO flag will be reset
STOP condition followed by a
START condition will be transmitted;
STO flag will be reset
Data byte will be received;
NOT ACK bit will be returned
Data byte will be received;
ACK bit will be returned
Repeated START condition will be transmitted
STOP condition will be transmitted;
STO flag will be reset
STOP condition followed by a
START condition will be transmitted;
STO flag will be reset
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Table 11.
Slave Receiver Mode
STATUS
CODE
(S1STA)
60H
68H
70H
78H
80H
88H
90H
98H
STATUS OF THE
I2C BUS AND
HARDWARE
APPLICATION SOFTWARE RESPONSE
NEXT ACTION TAKEN BY I2C HARDWARE
TO S1CON
TO/FROM S1DAT
STA
STO
SI
AA
Own SLA+W has
been received; ACK
h b
d
has
been returned
No S1DAT action or
X
0
0
0
no S1DAT action
X
0
0
1
Arbitration lost in
SLA+R/W as master;
Own SLA+W has
b
i d ACK
been
received,
returned
No S1DAT action or
X
0
0
0
Data byte will be received and NOT ACK will be
returned
no S1DAT action
X
0
0
1
Data byte will be received and ACK will be returned
General call address
(00H) has been
received; ACK has
received
been returned
No S1DAT action or
X
0
0
0
Data byte will be received and NOT ACK will be
returned
no S1DAT action
X
0
0
1
Data byte will be received and ACK will be returned
Arbitration lost in
SLA+R/W as master;
General call address
has been received,
received
ACK has been
returned
No S1DAT action or
X
0
0
0
Data byte will be received and NOT ACK will be
returned
no S1DAT action
X
0
0
1
Data byte will be received and ACK will be returned
Previously addressed
with own SLV
address; DATA has
b
i d ACK
been
received;
has been returned
Read data byte or
X
0
0
0
Data byte will be received and NOT ACK will be
returned
read data byte
X
0
0
1
Data byte will be received and ACK will be returned
Previously addressed
with own SLA; DATA
b
h been
b
byte
has
received; NOT ACK
has been returned
Read data byte or
0
0
0
0
read data byte or
0
0
0
1
read data byte or
1
0
0
0
read data byte
1
0
0
1
Switched to not addressed SLV mode; no recognition
of own SLA or General call address
Switched to not addressed SLV mode; Own SLA will
be recognized; General call address will be
recognized if S1ADR.0 = logic 1
Switched to not addressed SLV mode; no recognition
of own SLA or General call address. A START
condition will be transmitted when the bus becomes
free
Switched to not addressed SLV mode; Own SLA will
be recognized; General call address will be
recognized if S1ADR.0 = logic 1. A START condition
will be transmitted when the bus becomes free.
Previously addressed
with General Call;
DATA byte has been
received;
i d ACK h
has
been returned
Read data byte or
X
0
0
0
Data byte will be received and NOT ACK will be
returned
read data byte
X
0
0
1
Data byte will be received and ACK will be returned
Previously addressed
with General Call;
b
h been
b
DATA byte
has
received; NOT ACK
has been returned
Read data byte or
0
0
0
0
read data byte or
0
0
0
1
read data byte or
1
0
0
0
read data byte
1
0
0
1
Switched to not addressed SLV mode; no recognition
of own SLA or General call address
Switched to not addressed SLV mode; Own SLA will
be recognized; General call address will be
recognized if S1ADR.0 = logic 1
Switched to not addressed SLV mode; no recognition
of own SLA or General call address. A START
condition will be transmitted when the bus becomes
free
Switched to not addressed SLV mode; Own SLA will
be recognized; General call address will be
recognized if S1ADR.0 = logic 1. A START condition
will be transmitted when the bus becomes free.
2004 Apr 20
45
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Table 11.
Slave Receiver Mode (Continued)
STATUS
CODE
(S1STA)
STATUS OF THE
I2C BUS AND
HARDWARE
A0H
A STOP condition or
repeated START
di i h
condition
has b
been
received while still
addressed as
SLV/REC or SLV/TRX
Table 12.
B0H
B8H
C0H
C8H
NEXT ACTION TAKEN BY I2C HARDWARE
TO S1CON
TO/FROM S1DAT
STA
STO
SI
AA
No STDAT action or
0
0
0
0
No STDAT action or
0
0
0
1
No STDAT action or
1
0
0
0
No STDAT action
1
0
0
1
Switched to not addressed SLV mode; no recognition
of own SLA or General call address
Switched to not addressed SLV mode; Own SLA will
be recognized; General call address will be
recognized if S1ADR.0 = logic 1
Switched to not addressed SLV mode; no recognition
of own SLA or General call address. A START
condition will be transmitted when the bus becomes
free
Switched to not addressed SLV mode; Own SLA will
be recognized; General call address will be
recognized if S1ADR.0 = logic 1. A START condition
will be transmitted when the bus becomes free.
Slave Transmitter Mode
STATUS
CODE
(S1STA)
A8H
APPLICATION SOFTWARE RESPONSE
STATUS OF THE
I2C BUS AND
HARDWARE
APPLICATION SOFTWARE RESPONSE
NEXT ACTION TAKEN BY I2C HARDWARE
TO S1CON
TO/FROM S1DAT
STA
STO
SI
AA
Own SLA+R has
been received; ACK
h b
d
has
been returned
Load data byte or
X
0
0
0
load data byte
X
0
0
1
Arbitration lost in
SLA+R/W as master;
Own SLA+R has
been received, ACK
has been returned
Load data byte or
X
0
0
0
Last data byte will be transmitted and ACK bit will be
received
load data byte
X
0
0
1
Data byte will be transmitted; ACK bit will be received
Data byte in S1DAT
has been transmitted;
ACK has been
received
Load data byte or
X
0
0
0
Last data byte will be transmitted and ACK bit will be
received
load data byte
X
0
0
1
Data byte will be transmitted; ACK bit will be received
Data byte in S1DAT
has been transmitted;
NOT ACK has
h been
b
received
No S1DAT action or
0
0
0
01
no S1DAT action or
0
0
0
1
no S1DAT action or
1
0
0
0
no S1DAT action
1
0
0
1
Switched to not addressed SLV mode; no recognition
of own SLA or General call address
Switched to not addressed SLV mode; Own SLA will
be recognized; General call address will be
recognized if S1ADR.0 = logic 1
Switched to not addressed SLV mode; no recognition
of own SLA or General call address. A START
condition will be transmitted when the bus becomes
free
Switched to not addressed SLV mode; Own SLA will
be recognized; General call address will be
recognized if S1ADR.0 = logic 1. A START condition
will be transmitted when the bus becomes free.
No S1DAT action or
0
0
0
0
no S1DAT action or
0
0
0
1
no S1DAT action or
1
0
0
0
no S1DAT action
1
0
0
1
Last data byte in
S1DAT has been
i d (AA = 0);
0)
transmitted
ACK has been
received
2004 Apr 20
46
Last data byte will be transmitted and ACK bit will be
received
Data byte will be transmitted; ACK will be received
Switched to not addressed SLV mode; no recognition
of own SLA or General call address
Switched to not addressed SLV mode; Own SLA will
be recognized; General call address will be
recognized if S1ADR.0 = logic 1
Switched to not addressed SLV mode; no recognition
of own SLA or General call address. A START
condition will be transmitted when the bus becomes
free
Switched to not addressed SLV mode; Own SLA will
be recognized; General call address will be
recognized if S1ADR.0 = logic 1. A START condition
will be transmitted when the bus becomes free.
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Table 13.
Miscellaneous States
STATUS
CODE
(S1STA)
F8H
00H
STATUS OF THE
I2C BUS AND
HARDWARE
No relevant state
information available;
SI = 0
Bus error during MST
or selected slave
modes, due to an
illegal START or
STOP condition. State
00H can also occur
when interference
causes I2C to enter
an undefined state.
APPLICATION SOFTWARE RESPONSE
STA
No S1DAT action
No S1DAT action
STO
SI
AA
No S1CON action
0
1
0
Wait or proceed current transfer
X
Only the internal hardware is affected in the MST or
addressed SLV modes. In all cases, the bus is
released and I2C is switched to the not addressed
SLV mode. STO is reset.
the STO flag (no other bits in S1CON are affected). The SDA and
SCL lines are released (a STOP condition is not transmitted).
Slave Transmitter Mode: In the slave transmitter mode, a number
of data bytes are transmitted to a master receiver (see Figure 31).
Data transfer is initialized as in the slave receiver mode. When
S1ADR and S1CON have been initialized, I2C waits until it is
addressed by its own slave address followed by the data direction
bit which must be logic 1 (R) for the I2C to operate in the slave
transmitter mode. After its own slave address and the R bit have
been received, the serial interrupt flag (SI) is set and a valid status
code can be read from S1STA. This status code is used to vector to
an interrupt service routine, and the appropriate action to be taken
for each of these status codes is detailed in Table 12. The slave
transmitter mode may also be entered if arbitration is lost while I2C
is in the master mode (see state B0H).
Some Special Cases: The I2C hardware has facilities to handle the
following special cases that may occur during a serial transfer:
Simultaneous Repeated START Conditions from Two Masters
A repeated START condition may be generated in the master
transmitter or master receiver modes. A special case occurs if
another master simultaneously generates a repeated START
condition (see Figure 32). Until this occurs, arbitration is not lost by
either master since they were both transmitting the same data.
If the I2C hardware detects a repeated START condition on the
I2C-bus before generating a repeated START condition itself, it will
release the bus, and no interrupt request is generated. If another
master frees the bus by generating a STOP condition, I2C will
transmit a normal START condition (state 08H), and a retry of the
total serial data transfer can commence.
If the AA bit is reset during a transfer, I2C will transmit the last byte
of the transfer and enter state C0H or C8H. I2C is switched to the
not addressed slave mode and will ignore the master receiver if it
continues the transfer. Thus the master receiver receives all 1s as
serial data. While AA is reset, I2C does not respond to its own slave
address or a general call address. However, the I2C-bus is still
monitored, and address recognition may be resumed at any time by
setting AA. This means that the AA bit may be used to temporarily
isolate I2C from the I2C-bus.
DATA TRANSFER AFTER LOSS OF ARBITRATION
Arbitration may be lost in the master transmitter and master receiver
modes (see Figure 24). Loss of arbitration is indicated by the
following states in S1STA; 38H, 68H, 78H, and B0H (see Figures 28
and 29).
Miscellaneous States: There are two S1STA codes that do not
correspond to a defined I2C hardware state (see Table 13). These
are discussed below.
If the STA flag in S1CON is set by the routines which service these
states, then, if the bus is free again, a START condition (state 08H)
is transmitted without intervention by the CPU, and a retry of the
total serial transfer can commence.
S1STA = F8H:
This status code indicates that no relevant information is available
because the serial interrupt flag, SI, is not yet set. This occurs
between other states and when I2C is not involved in a serial
transfer.
FORCED ACCESS TO THE I2C-BUS
In some applications, it may be possible for an uncontrolled source
to cause a bus hang-up. In such situations, the problem may be
caused by interference, temporary interruption of the bus or a
temporary short-circuit between SDA and SCL.
S1STA = 00H:
This status code indicates that a bus error has occurred during an
I2C serial transfer. A bus error is caused when a START or STOP
condition occurs at an illegal position in the format frame. Examples
of such illegal positions are during the serial transfer of an address
byte, a data byte, or an acknowledge bit. A bus error may also be
caused when external interference disturbs the internal I2C signals.
When a bus error occurs, SI is set. To recover from a bus error, the
STO flag must be set and SI must be cleared. This causes I2C to
enter the “not addressed” slave mode (a defined state) and to clear
2004 Apr 20
NEXT ACTION TAKEN BY I2C HARDWARE
TO S1CON
TO/FROM S1DAT
If an uncontrolled source generates a superfluous START or masks
a STOP condition, then the I2C-bus stays busy indefinitely. If the
STA flag is set and bus access is not obtained within a reasonable
amount of time, then a forced access to the I2C-bus is possible. This
is achieved by setting the STO flag while the STA flag is still set. No
STOP condition is transmitted. The I2C hardware behaves as if a
STOP condition was received and is able to transmit a START
condition. The STO flag is cleared by hardware (see Figure 33).
47
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
S
SLA
08H
W
A
DATA
18H
A
S
BOTH MASTERS CONTINUE
WITH SLA TRANSMISSION
28H
OTHER MASTER SENDS REPEATED
START CONDITION EARLIER
SU00975
Figure 32. Simultaneous Repeated START Conditions from 2 Masters
TIME OUT
STA FLAG
SDA LINE
SCL LINE
START CONDITION
Figure 33. Forced Access to a Busy
I2C-BUS OBSTRUCTED BY A LOW LEVEL ON SCL OR SDA
An I2C-bus hang-up occurs if SDA or SCL is pulled LOW by an
uncontrolled source. If the SCL line is obstructed (pulled LOW) by a
device on the bus, no further serial transfer is possible, and the I2C
hardware cannot resolve this type of problem. When this occurs, the
problem must be resolved by the device that is pulling the SCL bus
line LOW.
performs the same action as described above. In each case, state
08H is entered after a successful START condition is transmitted
and normal serial transfer continues. Note that the CPU is not
involved in solving these bus hang-up problems.
BUS ERROR
A bus error occurs when a START or STOP condition is present at
an illegal position in the format frame. Examples of illegal positions
are during the serial transfer of an address byte, a data or an
acknowledge bit.
If the SDA line is obstructed by another device on the bus (e.g., a
slave device out of bit synchronization), the problem can be solved
by transmitting additional clock pulses on the SCL line (see Figure
34). The I2C hardware transmits additional clock pulses when the
STA flag is set, but no START condition can be generated because
the SDA line is pulled LOW while the I2C-bus is considered free.
The I2C hardware attempts to generate a START condition after
every two additional clock pulses on the SCL line. When the SDA
line is eventually released, a normal START condition is transmitted,
state 08H is entered, and the serial transfer continues.
The I2C hardware only reacts to a bus error when it is involved in a
serial transfer either as a master or an addressed slave. When a
bus error is detected, I2C immediately switches to the not addressed
slave mode, releases the SDA and SCL lines, sets the interrupt flag,
and loads the status register with 00H. This status code may be
used to vector to a service routine which either attempts the aborted
serial transfer again or simply recovers from the error condition as
shown in Table 13.
If a forced bus access occurs or a repeated START condition is
transmitted while SDA is obstructed (pulled LOW), the I2C hardware
2004 Apr 20
SU00976
I2C-bus
48
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
STA FLAG
(2)
SDA LINE
(1)
(3)
(1)
SCL LINE
START CONDITION
(1) Unsuccessful attempt to send a Start condition
(2) SDA line released
(3) Successful attempt to send a Start condition; state 08H is entered
SU00977
Figure 34. Recovering from a Bus Obstruction Caused by a Low Level on SDA
I2C INTERRUPT ROUTINE
When the I2C interrupt is entered, the PSW is first pushed on the
stack. Then S1STA and HADD (loaded with the high-order address
byte of the 26 service routines by the initialization routine) are
pushed on to the stack. S1STA contains a status code which is the
lower byte of one of the 26 service routines. The next instruction is
RET, which is the return from subroutine instruction. When this
instruction is executed, the HIGH and LOW order address bytes are
popped from stack and loaded into the program counter.
Software Examples of I2C Service Routines: This section
consists of a software example for:
– Initialization of I2C after a RESET
– Entering the I2C interrupt routine
– The 26 state service routines for the
– Master transmitter mode
– Master receiver mode
– Slave receiver mode
– Slave transmitter mode
The next instruction to be executed is the first instruction of the state
service routine. Seven bytes of program code (which execute in
eight machine cycles) are required to branch to one of the 26 state
service routines.
INITIALIZATION
In the initialization routine, I2C is enabled for both master and slave
modes. For each mode, a number of bytes of internal data RAM are
allocated to the SIO to act as either a transmission or reception
buffer. In this example, 8 bytes of internal data RAM are reserved for
different purposes. The data memory map is shown in Figure 35.
The initialization routine performs the following functions:
– S1ADR is loaded with the part’s own slave address and the
general call bit (GC)
– P1.6 and P1.7 bit latches are loaded with logic 1s
– RAM location HADD is loaded with the high-order address byte of
the service routines
– The I2C interrupt enable and interrupt priority bits are set
– The slave mode is enabled by simultaneously setting the ENS1
and AA bits in S1CON and the serial clock frequency (for master
modes) is defined by loading CR0 and CR1 in S1CON. The
master routines must be started in the main program.
SI
PUSH HADD
RET
Save PSW
Push status code
(low order address byte)
Push HIGH order address byte
Jump to state service routine
The state service routines are located in a 256-byte page of program
memory. The location of this page is defined in the initialization
routine. The page can be located anywhere in program memory by
loading data RAM register HADD with the page number. Page 01 is
chosen in this example, and the service routines are located
between addresses 0100H and 01FFH.
THE STATE SERVICE ROUTINES
The state service routines are located 8 bytes from each other. Eight
bytes of code are sufficient for most of the service routines. A few of
the routines require more than 8 bytes and have to jump to other
locations to obtain more bytes of code. Each state routine is part of
the I2C interrupt routine and handles one of the 26 states. It ends
with a RETI instruction which causes a return to the main program.
The I2C hardware now begins checking the I2C-bus for its own slave
address and general call. If the general call or the own slave
address is detected, an interrupt is requested and S1STA is loaded
with the appropriate state information. The following text describes a
fast method of branching to the appropriate service routine.
2004 Apr 20
PUSH PSW
PUSH S1STA
49
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
SPECIAL FUNCTION REGISTERS
S1ADR
GC
S1DAT
S1STA
S1CON
CR2
ENS1
STA
ST0
SI
0
0
AA
CR!
PSW
P1
0
CR0
D9
D8
D0
IPO
IEN0
DB
DA
EA
P1.7
PS1
B8
ES1
AB
90
P1.6
80
INTERNAL DATA RAM
7F
BACKUP
NUMBYTMST
SLA
HADD
ORIGINAL VALUE OF NUMBYTMST
53
NUMBER OF BYTES AS MASTER
52
SLA+R/W TO BE TRANSMITTED TO SLA
51
HIGHER ADDRESS BYTE INTERRUPT ROUTINE
50
4F
SLAVE TRANSMITTER DATA RAM
48
STD
SLAVE RECEIVER DATA RAM
40
SRD
MASTER RECEIVER DATA RAM
38
MRD
MASTER TRANSMITTER DATA RAM
30
MTD
R1
19
R0
18
00
SU00978
Figure 35.
2004 Apr 20
I 2C
Data Memory Map
50
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
occurs, the I2C-bus is released and I2C enters the not selected
slave receiver mode.
MASTER TRANSMITTER AND MASTER RECEIVER MODES
The master mode is entered in the main program. To enter the
master transmitter mode, the main program must first load the
internal data RAM with the slave address, data bytes, and the
number of data bytes to be transmitted. To enter the master receiver
mode, the main program must first load the internal data RAM with
the slave address and the number of data bytes to be received. The
R/W bit determines whether I2C operates in the master transmitter
or master receiver mode.
In the slave receiver mode, a maximum of 8 received data bytes can
be stored in the internal data RAM. A maximum of 8 bytes ensures
that other RAM locations are not overwritten if a master sends more
bytes. If more than 8 bytes are transmitted, a not acknowledge is
returned, and I2C enters the not addressed slave receiver mode. A
maximum of one received data byte can be stored in the internal
data RAM after a general call address is detected. If more than one
byte is transmitted, a not acknowledge is returned and I2C enters
the not addressed slave receiver mode.
Master mode operation commences when the STA bit in S1CION is
set by the SETB instruction and data transfer is controlled by the
master state service routines in accordance with Table 9, Table 10,
Figure 28, and Figure 29. In the example below, 4 bytes are
transferred. There is no repeated START condition. In the event of
lost arbitration, the transfer is restarted when the bus becomes free.
If a bus error occurs, the I2C-bus is released and I2C enters the not
selected slave receiver mode. If a slave device returns a not
acknowledge, a STOP condition is generated.
In the slave transmitter mode, data to be transmitted is obtained
from the same locations in the internal data RAM that were
previously loaded by the main program. After a not acknowledge
has been returned by a master receiver device, I2C enters the not
addressed slave mode.
ADAPTING THE SOFTWARE FOR DIFFERENT APPLICATIONS
The following software example shows the typical structure of the
interrupt routine including the 26 state service routines and may be
used as a base for user applications. If one or more of the four
modes are not used, the associated state service routines may be
removed but, care should be taken that a deleted routine can never
be invoked.
A repeated START condition can be included in the serial transfer if
the STA flag is set instead of the STO flag in the state service
routines vectored to by status codes 28H and 58H. Additional
software must be written to determine which data is transferred after
a repeated START condition.
SLAVE TRANSMITTER AND SLAVE RECEIVER MODES
After initialization, I2C continually tests the I2C-bus and branches to
one of the slave state service routines if it detects its own slave
address or the general call address (see Table 11, Table 12, Figure
30, and Figure 31). If arbitration was lost while in the master mode,
the master mode is restarted after the current transfer. If a bus error
2004 Apr 20
P83C654X2/P87C654X2
This example does not include any time-out routines. In the slave
modes, time-out routines are not very useful since, in these modes,
I2C behaves essentially as a passive device. In the master modes,
an internal timer may be used to cause a time-out if a serial transfer
is not complete after a defined period of time. This time period is
defined by the system connected to the I2C-bus.
51
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
00D8
00D9
00DA
00DB
!********************************************************************************************************
! SI01 EQUATE LIST
!********************************************************************************************************
!********************************************************************************************************
! LOCATIONS OF THE SI01 SPECIAL FUNCTION REGISTERS
!********************************************************************************************************
S1CON
–0xd8
S1STA
–0xd9
S1DAT
–0xda
S1ADR
–0xdb
00A8
00B8
IEN0
IP0
–0xa8
–02b8
!********************************************************************************************************
! BIT LOCATIONS
!********************************************************************************************************
00DD
00BD
00D5
00C5
00C1
00E5
STA
SI01HP
–0xdd
–0xbd
! STA bit in S1CON
! IP0, SI01 Priority bit
!********************************************************************************************************
! IMMEDIATE DATA TO WRITE INTO REGISTER S1CON
!********************************************************************************************************
ENS1_NOTSTA_STO_NOTSI_AA_CR0
–0xd5
! Generates STOP
! (CR0 = 100kHz)
ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
–0xc5
! Releases BUS and
! ACK
ENS1_NOTSTA_NOTSTO_NOTSI_NOTAA_CR0
–0xc1
! Releases BUS and
! NOT ACK
ENS1_STA_NOTSTO_NOTSI_AA_CR0
–0xe5
! Releases BUS and
! set STA
0001
00C0
00C1
0018
!********************************************************************************************************
! GENERAL IMMEDIATE DATA
!********************************************************************************************************
OWNSLA –0x31
! Own SLA+General Call
! must be written into S1ADR
ENSI01
–0xa0
! EA+ES1, enable I2C interrupt
! must be written into IEN0
PAG1
–0x01
! select PAG1 as HADD
SLAW
–0xc0
! SLA+W to be transmitted
SLAR
–0xc1
! SLA+R to be transmitted
SELRB3 –0x18
! Select Register Bank 3
0030
0038
0040
0048
!********************************************************************************************************
! LOCATIONS IN DATA RAM
!********************************************************************************************************
MTD
–0x30
! MST/TRX/DATA base address
MRD
–0x38
! MST/REC/DATA base address
SRD
–0x40
! SLV/REC/DATA base address
STD
–0x48
! SLV/TRX/DATA base address
0053
BACKUP
–0x53
0052
NUMBYTMST
–0x52
0051
SLA
–0x51
0050
HADD
–0x50
0031
00A0
2004 Apr 20
! Backup from NUMBYTMST
! To restore NUMBYTMST in case
! of an Arbitration Loss.
! Number of bytes to transmit
! or receive as MST.
! Contains SLA+R/W to be
! transmitted.
! High Address byte for STATE 0
! till STATE 25.
52
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
4100
!********************************************************************************************************
! INITIALIZATION ROUTINE
! Example to initialize IIC Interface as slave receiver or slave transmitter and
! start a MASTER TRANSMIT or a MASTER RECEIVE function. 4 bytes will be transmitted or received.
!********************************************************************************************************
.sect
strt
.base
0x00
ajmp INIT
! RESET
0200
75DB31
.sect
.base
INIT:
0203
0205
0207
020A
020D
020F
D296
D297
755001
43A8A0
C2BD
75D8C5
0000
initial
0x200
mov
S1ADR,#OWNSLA
! Load own SLA + enable
! general call recognition
! P1.6 High level.
! P1.7 High level.
setb
setb
mov
orl
clr
mov
P1(6)
P1(7)
HADD,#PAG1
IEN0,#ENSI01
! Enable SI01 interrupt
SI01HP
! SI01 interrupt low priority
S1CON, #ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! Initialize SLV funct.
!********************************************************************************************************
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! START MASTER TRANSMIT FUNCTION
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
0212
0215
0218
021A
021D
0220
755204
7551C0
D2DD
755204
7551C1
D2DD
mov
mov
setb
NUMBYTMST,#0x4
SLA,#SLAW
STA
! Transmit 4 bytes.
! SLA+W, Transmit funct.
! set STA in S1CON
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! START MASTER RECEIVE FUNCTION
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
mov NUMBYTMST,#0x4
! Receive 4 bytes.
mov SLA,#SLAR
! SLA+R, Receive funct.
setb STA
! set STA in S1CON
!********************************************************************************************************
! SI01 INTERRUPT ROUTINE
!********************************************************************************************************
.sect
intvec
! SI01 interrupt vector
.base
0x00
! S1STA and HADD are pushed onto the stack.
! They serve as return address for the RET instruction.
! The RET instruction sets the Program Counter to address HADD,
! S1STA and jumps to the right subroutine.
002B
002D
002F
0031
C0D0
C0D9
C050
22
push psw
push S1STA
push HADD
ret
! save psw
! JMP to address HADD,S1STA.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 00, Bus error.
! ACTION : Enter not addressed SLV mode and release bus. STO reset.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
st0
.base
0x100
0100
75D8D5
mov
0103
0105
D0D0
32
pop
reti
2004 Apr 20
S1CON,#ENS1_NOTSTA_STO_NOTSI_AA_CR0 ! clr SI
! set STO,AA
psw
53
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
!********************************************************************************************************
!********************************************************************************************************
! MASTER STATE SERVICE ROUTINES
!********************************************************************************************************
! State 08 and State 10 are both for MST/TRX and MST/REC.
! The R/W bit decides whether the next state is within
! MST/TRX mode or within MST/REC mode.
!********************************************************************************************************
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 08, A, START condition has been transmitted.
! ACTION : SLA+R/W are transmitted, ACK bit is received.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mts8
.base
0x108
0108
010B
8551DA
75D8C5
010E
01A0
mov
mov
S1DAT,SLA
! Load SLA+R/W
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI
ajmp INITBASE1
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 10, A repeated START condition has been
!
transmitted.
! ACTION : SLA+R/W are transmitted, ACK bit is received.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mts10
.base
0x110
0110
0113
8551DA
75D8C5
010E
01A0
00A0
00A3
00A5
00A7
00AA
00AC
75D018
7930
7838
855253
D0D0
32
mov
mov
S1DAT,SLA
! Load SLA+R/W
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI
ajmp INITBASE1
.sect
ibase1
.base
0xa0
INITBASE1:
mov
mov
mov
mov
pop
reti
psw,#SELRB3
r1,#MTD
r0,#MRD
BACKUP,NUMBYTMST
psw
! Save initial value
!********************************************************************************************************
!********************************************************************************************************
! MASTER TRANSMITTER STATE SERVICE ROUTINES
!********************************************************************************************************
!********************************************************************************************************
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 18, Previous state was STATE 8 or STATE 10, SLA+W have been transmitted,
!
ACK has been received.
! ACTION : First DATA is transmitted, ACK bit is received.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mts18
.base
0x118
0118
011B
011D
75D018
87DA
01B5
2004 Apr 20
mov psw,#SELRB3
mov S1DAT,@r1
ajmp CON
54
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 20, SLA+W have been transmitted, NOT ACK has been received
! ACTION : Transmit STOP condition.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mts20
.base
0x120
0120
75D8D5
mov
0123
0125
D0D0
32
pop
reti
S1CON,#ENS1_NOTSTA_STO_NOTSI_AA_CR0
! set STO, clr SI
psw
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 28, DATA of S1DAT have been transmitted, ACK received.
! ACTION : If Transmitted DATA is last DATA then transmit a STOP condition,
!
else transmit next DATA.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mts28
.base
0x128
0128
012B
D55285
75D8D5
012E
01B9
djnz
mov
NUMBYTMST,NOTLDAT1
! JMP if NOT last DATA
S1CON,#ENS1_NOTSTA_STO_NOTSI_AA_CR0
! clr SI, set AA
ajmp RETmt
.sect
mts28sb
.base
0x0b0
NOTLDAT1:
00B0
00B3
00B5
75D018
87DA
75D8C5
00B8
00B9
00BB
09
D0D0
32
0130
75D8D5
mov
0133
0135
D0D0
32
pop
reti
CON:
mov
mov
mov
psw,#SELRB3
S1DAT,@r1
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
r1
psw
inc
pop
reti
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 30, DATA of S1DAT have been transmitted, NOT ACK received.
! ACTION : Transmit a STOP condition.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mts30
.base
0x130
RETmt
:
S1CON,#ENS1_NOTSTA_STO_NOTSI_AA_CR0
! set STO, clr SI
psw
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 38, Arbitration lost in SLA+W or DATA.
! ACTION : Bus is released, not addressed SLV mode is entered.
!
A new START condition is transmitted when the IIC-bus is free again.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mts38
.base
0x138
0138
013B
013E
75D8E5
855352
01B9
2004 Apr 20
mov S1CON,#ENS1_STA_NOTSTO_NOTSI_AA_CR0
mov NUMBYTMST,BACKUP
ajmp RETmt
55
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
!********************************************************************************************************
!********************************************************************************************************
! MASTER RECEIVER STATE SERVICE ROUTINES
!********************************************************************************************************
!********************************************************************************************************
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 40, Previous state was STATE 08 or STATE 10,
!
SLA+R have been transmitted, ACK received.
! ACTION : DATA will be received, ACK returned.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mts40
.base
0x140
0140
75D8C5
mov
0143
D0D0
32
pop
reti
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr STA, STO, SI set AA
psw
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 48, SLA+R have been transmitted, NOT ACK received.
! ACTION : STOP condition will be generated.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mts48
.base
0x148
0148
75D8D5
014B
014D
D0D0
32
STOP:
mov
pop
reti
S1CON,#ENS1_NOTSTA_STO_NOTSI_AA_CR0
! set STO, clr SI
psw
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 50, DATA have been received, ACK returned.
! ACTION : Read DATA of S1DAT.
!
DATA will be received, if it is last DATA
then NOT ACK will be returned else ACK will be returned.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mrs50
.base
0x150
0150
0153
0155
75D018
A6DA
01C0
mov psw,#SELRB3
mov @r0,S1DAT
ajmp REC1
.sect
.base
00C0
00C3
D55205
75D8C1
00C6
00C8
8003
75D8C5
00CB
00CC
00CE
08
D0D0
32
mrs50s
0xc0
REC1:
NOTLDAT2:
RETmr:
! Read received DATA
djnz
mov
NUMBYTMST,NOTLDAT2
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_NOTAA_CR0
! clr SI,AA
sjmp RETmr
mov S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
inc
r0
pop psw
reti
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 58, DATA have been received, NOT ACK returned.
! ACTION : Read DATA of S1DAT and generate a STOP condition.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
mrs58
.base
0x158
0158
015B
015D
75D018
A6DA
80E9
2004 Apr 20
mov psw,#SELRB3
mov @R0,S1DAT
sjmp STOP
56
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
!********************************************************************************************************
!********************************************************************************************************
! SLAVE RECEIVER STATE SERVICE ROUTINES
!********************************************************************************************************
!********************************************************************************************************
0160
75D8C5
0163
0166
75D018
01D0
00D0
00D2
00D4
00D6
7840
7908
D0D0
32
0168
016B
016E
75D8E5
75D018
01D0
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 60, Own SLA+W have been received, ACK returned.
! ACTION : DATA will be received and ACK returned.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
srs60
.base
0x160
mov S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
mov psw,#SELRB3
ajmp INITSRD
.sect
insrd
.base
0xd0
INITSRD:
mov
mov
pop
reti
r0,#SRD
r1,#8
psw
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 68, Arbitration lost in SLA and R/W as MST
!
Own SLA+W have been received, ACK returned
! ACTION : DATA will be received and ACK returned.
!
STA is set to restart MST mode after the bus is free again.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
srs68
.base
0x168
mov S1CON,#ENS1_STA_NOTSTO_NOTSI_AA_CR0
mov psw,#SELRB3
ajmp INITSRD
0170
75D8C5
0173
0176
75D018
01D0
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 70, General call has been received, ACK returned.
! ACTION : DATA will be received and ACK returned.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
srs70
.base
0x170
mov S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
mov psw,#SELRB3
! Initialize SRD counter
ajmp initsrd
75D8E5
75D018
01D0
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 78, Arbitration lost in SLA+R/W as MST.
!
General call has been received, ACK returned.
! ACTION : DATA will be received and ACK returned.
!
STA is set to restart MST mode after the bus is free again.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
srs78
.base
0x178
mov S1CON,#ENS1_STA_NOTSTO_NOTSI_AA_CR0
mov psw,#SELRB3
! Initialize SRD counter
ajmp INITSRD
0178
017B
017E
2004 Apr 20
57
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 80, Previously addressed with own SLA. DATA received, ACK returned.
! ACTION : Read DATA.
!
IF received DATA was the last
!
THEN superfluous DATA will be received and NOT ACK returned
ELSE next DATA will be received and ACK returned.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
srs80
.base
0x180
0180
0183
0185
75D018
A6DA
01D8
mov psw,#SELRB3
mov @r0,S1DAT
ajmp REC2
.sect
.base
00D8
00DA
D906
75D8C1
00DD
00DF
00E0
D0D0
32
75D8C5
00E3
00E4
00E6
08
D0D0
32
srs80s
0xd8
REC2:
LDAT:
djnz
mov
NOTLDAT3:
pop
reti
mov
RETsr:
! Read received DATA
inc
pop
reti
r1,NOTLDAT3
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_NOTAA_CR0
! clr SI,AA
psw
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
r0
psw
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 88, Previously addressed with own SLA. DATA received NOT ACK returned.
! ACTION : No save of DATA, Enter NOT addressed SLV mode.
!
Recognition of own SLA. General call recognized, if S1ADR. 0–1.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
srs88
.base
0x188
0188
75D8C5
018B
01E4
mov
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
ajmp RETsr
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 90, Previously addressed with general call.
!
DATA has been received, ACK has been returned.
! ACTION : Read DATA.
After General call only one byte will be received with ACK
!
the second DATA will be received with NOT ACK.
!
DATA will be received and NOT ACK returned.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
srs90
.base
0x190
0190
0193
0195
75D018
A6DA
01DA
0198
75D8C5
mov
019B
019D
D0D0
32
pop
reti
2004 Apr 20
mov psw,#SELRB3
mov @r0,S1DAT
! Read received DATA
ajmp LDAT
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: 98, Previously addressed with general call.
!
DATA has been received, NOT ACK has been returned.
! ACTION : No save of DATA, Enter NOT addressed SLV mode.
Recognition of own SLA. General call recognized, if S1ADR. 0–1.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
srs98
.base
0x198
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
psw
58
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: A0, A STOP condition or repeated START has been received,
!
while still addressed as SLV/REC or SLV/TRX.
! ACTION : No save of DATA, Enter NOT addressed SLV mode.
!
Recognition of own SLA. General call recognized, if S1ADR. 0–1.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
srsA0
.base
0x1a0
01A0
75D8C5
mov
01A3
01A5
D0D0
32
pop
reti
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
psw
!********************************************************************************************************
!********************************************************************************************************
! SLAVE TRANSMITTER STATE SERVICE ROUTINES
!********************************************************************************************************
!********************************************************************************************************
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: A8, Own SLA+R received, ACK returned.
! ACTION : DATA will be transmitted, A bit received.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
stsa8
.base
0x1a8
01A8
01AB
8548DA
75D8C5
01AE
01E8
00E8
00EB
00ED
00EE
00F0
75D018
7948
09
D0D0
32
mov
mov
S1DAT,STD
! load DATA in S1DAT
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
ajmp INITBASE2
.sect
ibase2
.base
0xe8
INITBASE2:
mov
mov
inc
pop
reti
psw,#SELRB3
r1, #STD
r1
psw
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: B0, Arbitration lost in SLA and R/W as MST. Own SLA+R received, ACK returned.
! ACTION : DATA will be transmitted, A bit received.
!
STA is set to restart MST mode after the bus is free again.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
stsb0
.base
0x1b0
01B0
01B3
01B6
8548DA
75D8E5
01E8
2004 Apr 20
mov S1DAT,STD
! load DATA in S1DAT
mov S1CON,#ENS1_STA_NOTSTO_NOTSI_AA_CR0
ajmp INITBASE2
59
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
01B8
01BB
01BD
75D018
87DA
01F8
P83C654X2/P87C654X2
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: B8, DATA has been transmitted, ACK received.
! ACTION : DATA will be transmitted, ACK bit is received.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
stsb8
.base
0x1b8
mov psw,#SELRB3
mov S1DAT,@r1
ajmp SCON
.sect
.base
scn
0xf8
00F8
75D8C5
SCON:
00FB
00FC
00FE
09
D0D0
32
01C0
75D8C5
01C3
01C5
D0D0
32
inc
pop
reti
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: C0, DATA has been transmitted, NOT ACK received.
! ACTION : Enter not addressed SLV mode.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
stsc0
.base
0x1c0
mov S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
pop psw
reti
01C8
75D8C5
01CB
01CD
D0D0
32
mov
S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
r1
psw
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! STATE
: C8, Last DATA has been transmitted (AA=0), ACK received.
! ACTION : Enter not addressed SLV mode.
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
.sect
stsc8
.base
0x1c8
mov S1CON,#ENS1_NOTSTA_NOTSTO_NOTSI_AA_CR0
! clr SI, set AA
pop psw
reti
!********************************************************************************************************
!********************************************************************************************************
! END OF SI01 INTERRUPT ROUTINE
!********************************************************************************************************
!********************************************************************************************************
2004 Apr 20
60
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
The function of the IPH SFR, 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:
Interrupt Priority Structure
The P8xC654X2 has an 8 source four-level interrupt structure (see
Table 14).
There are four SFRs associated with the four-level interrupt. They
are IE, IEN1, IP, and IPH. The IPH (Interrupt Priority High) register
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 38.
Table 14.
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)
Interrupt Table
SOURCE
POLLING PRIORITY
REQUEST BITS
X0
1
IE0
HARDWARE CLEAR?
SI01 (I2C)
2
–
N
2BH
T0
3
TP0
Y
0BH
X1
4
IE1
N (L) Y (T)
13H
T1
5
TF1
Y
1BH
SP
6
RI, TI
N
23H
T2
7
TF2, EXF2
N
3BH
N (L)1
Y (T)2
VECTOR ADDRESS
03H
NOTES:
1. L = Level activated
2. T = Transition activated
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.
The priority scheme for servicing the interrupts is the same as that
for the 80C51, except there are four interrupt levels rather than two
as on the 80C51. 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
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.
–
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.
SU01745
Figure 36. IE Registers
2004 Apr 20
61
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
IP (0B8H)
7
6
5
4
3
2
1
0
–
–
PT2
PS
PT1
PX1
PT0
PX0
Priority Bit = 1 assigns high priority
Priority Bit = 0 assigns low 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
–
–
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.
SU01743
Figure 37. 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
–
–
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.
SU01744
Figure 38. IPH Registers
2004 Apr 20
62
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
The GPS bit is a general purpose user-defined flag. 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 AUXR1 instruction
without affecting the GPS bit.
Reduced EMI Mode
The AO bit (AUXR.0) in the AUXR register when set disables the
ALE output unless the CPU needs to perform an off-chip memory
access.
Reduced EMI Mode
AUXR (8EH)
DPS
7
6
5
4
3
2
1
0
–
–
–
–
Fast/
STD
I2C
–
–
AO
AUXR.0
BIT0
AUXR1
DPTR1
DPTR0
DPH
(83H)
AO
DPL
(82H)
Dual DPTR
SU00745A
The dual DPTR structure (see Figure 39) is a way by which the chip
will 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 39.
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: xxxxxxx0B
AUXR1 (A2H)
7
6
5
4
3
2
1
0
–
–
–
LPEP
GFS
0
–
DPS
Where:
DPS = AUXR1/bit0 = Switches between DPTR0 and DPTR1.
Select Reg
DPS
DPTR0
0
DPTR1
1
INC DPTR
Increments the data pointer by 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.
FF
FFFF
FF
UPPER
128 BYTES
INTERNAL RAM
80
EXTERNAL
DATA
MEMORY
SPECIAL
FUNCTION
REGISTER
EXTERNAL
DATA
MEMORY
80
LOWER
128 BYTES
INTERNAL RAM
00
0000
00
SU01741
Figure 40. Internal and External Data Memory Address Space with EXTRAM = 0
2004 Apr 20
63
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
HARDWARE WATCHDOG TIMER (ONE-TIME
ENABLED WITH RESET-OUT FOR P8XC654X2)
Using the WDT
To enable the WDT, the user must write 01EH and 0E1H in sequence
to the WDTRST, SFR location 0A6H. When the WDT is enabled, the
user needs to service it by writing 01EH and 0E1H to WDTRST to
avoid a WDT overflow. The 14-bit counter overflows when it reaches
16383 (3FFFH) and this will reset the device. When the WDT is
enabled, it will increment every machine cycle while the oscillator is
running. This means the user must reset the WDT at least every
16383 machine cycles. To reset the WDT, the user must write 01EH
and 0E1H to WDTRST. WDTRST is a write only register. The WDT
counter cannot be read or written. When the WDT overflows, it will
generate an output RESET pulse at the reset pin (see note below).
The RESET pulse duration is 98 × Tosc (6-clock mode; 196 in
12-clock mode), where Tosc = 1/fosc. To make the best use of the
WDT, it should be serviced in those sections of code that will
periodically be executed within the time required to prevent a WDT
reset.
The WDT is intended as a recovery method in situations where the
CPU may be subjected to software upset. The WDT consists of a
14-bit counter and the WatchDog Timer reset (WDTRST) SFR. The
WDT is disabled at reset.
2004 Apr 20
64
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
ABSOLUTE MAXIMUM RATINGS1, 2, 3
PARAMETER
Operating temperature under bias
RATING
UNIT
0 to +70 or –40 to +85
°C
–65 to +150
°C
0 to +13.0
V
Storage temperature range
Voltage on EA/VPP pin to VSS
Voltage on any other pin to VSS
4
Maximum IOL per I/O pin
–0.5 to +6.0
V
15
mA
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.
4. Transient voltage only.
AC ELECTRICAL CHARACTERISTICS
Tamb = 0°C to +70°C or –40°C to +85°C
CLOCK FREQUENCY
RANGE
SYMBOL
1/tCLCL
2004 Apr 20
FIGURE
PARAMETER
46
Oscillator frequency
OPERATING MODE
POWER SUPPLY
VOLTAGE
MIN
MAX
UNIT
6-clock
5 V "10 %
0
30
MHz
6-clock
2.7 V to 5.5 V
0
16
MHz
12-clock
5 V "10 %
0
33
MHz
12-clock
2.7 V to 5.5 V
0
16
MHz
65
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
DC ELECTRICAL CHARACTERISTICS
Tamb = 0 °C to +70 °C or –40 °C to +85 °C; VCC = 2.7 V to 5.5 V; VSS = 0 V (16 MHz max. CPU clock)
SYMBOL
PARAMETER
TEST
CONDITIONS
LIMITS
MIN
VIL
Input LOW
voltage11,
except P1.6 and P1.7
UNIT
TYP1
MAX
4.0 V < VCC < 5.5 V
–0.5
0.2VCC – 0.1
V
2.7 V < VCC < 4.0 V
–0.5
0.7VCC
V
VIL1
Input LOW voltage to EA
–0.5
0.2VDD – 0.3
V
VIL2
Input LOW voltage to P1.6/SCL, P1.7/SDA5
–0.5
0.3VDD
V
VIH
Input HIGH voltage (ports 0, 1, 2, 3, EA)
0.2VCC + 0.9
VCC + 0.5
V
VIH1
Input HIGH voltage, XTAL1, RST11
0.7VCC
VCC + 0.5
V
mA2
–
0.4
V
28,
VOL
Output LOW voltage, ports 1,
and P1.7
except P1.6 VCC = 2.7 V; IOL = 1.6
VOL1
Output LOW voltage, port 0, ALE, PSEN8, 7
VCC = 2.7 V; IOL = 3.2 mA2
–
0.4
V
VOL2
Output LOW voltage, P1.6/SCL, P1.7/SDA
I
–
0.4
V
VOH
Output HIGH voltage, ports 1, 2, 3 3
VCC = 2.7 V; IOH = –20 mA
VCC – 0.7
–
V
VCC = 4.5 V; IOH = –30 mA
VCC – 0.7
–
V
OL
= 3.0 mA7
VOH1
Output HIGH voltage (port 0 in external bus VCC = 2.7 V; IOH = –3.2 mA
mode), ALE9, PSEN3
VCC – 0.7
–
V
IIL
Logical 0 input current, ports 1, 2, 3
VIN = 0.4 V
–1
–50
mA
ITL
Logical 1-to-0 transition current, ports 1, 2, 36
VIN = 2.0 V; See note 4
–
–650
mA
ILI
Input leakage current, port 0
0.45 < VIN < VCC – 0.3
–
±10
mA
ICC
Power supply current (see Figure 49 and
Source Code):
mA
Active mode @ 16 MHz
mA
Idle mode @ 16 MHz
Power-down mode or clock stopped
(see Figure 45 for conditions) 12
Tamb = 0 °C to 70 °C
Tamb = –40 °C to +85 °C
2
30
mA
3
50
mA
VRAM
RAM keep-alive voltage
1.2
RRST
Internal reset pull-down resistor
40
225
V
kΩ
CIO
Pin capacitance10 (except EA)
–
15
pF
NOTES:
1. Typical ratings are not guaranteed. Values listed are based on tests conducted on limited number of samples at room temperature.
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 > 100 pF), the noise pulse on the ALE pin may exceed 0.8 V. 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 5 mA 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 2 V.
5. See Figures 51 through 54 for ICC test conditions and Figure 49 for ICC vs. Frequency
12-clock mode characteristics:
Active mode (operating): ICC = 1.0 mA + 1.1 mA × FREQ.[MHz]
Active mode (reset):
ICC = 7.0 mA + 0.6 mA FREQ.[MHz]
Idle mode:
ICC = 1.0 mA + 0.22 mA FREQ.[MHz]
6. This value applies to Tamb = 0 °C to +70 °C. For Tamb = –40 °C to +85 °C, ITL = –750 mA.
7. Load capacitance for port 0, ALE, and PSEN = 100 pF, load capacitance for all other outputs = 80 pF.
8. Under steady state (non-transient) conditions, IOL must be externally limited as follows:
15 mA (*NOTE: This is 85 °C specification.)
Maximum IOL per port pin:
26 mA
Maximum IOL per 8-bit port:
Maximum total IOL for all outputs:
71 mA
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 25 pF. Pin capacitance of ceramic package is less than 15 pF
(except EA is 25 pF).
2004 Apr 20
66
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
11. To improve noise rejection a nominal 100 ns glitch rejection circuitry has been added to the RST pin, and a nominal 15 ns glitch rejection
circuitry has been added to the INT0 and INT1 pins. Previous devices provided only an inherent 5 ns of glitch rejection.
12. Power-down mode for 3 V range: Commercial Temperature Range – typ: 0.5 mA, max. 20 mA; Industrial Temperature Range – typ. 1.0 mA,
max. 30 mA;
2004 Apr 20
67
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
DC ELECTRICAL CHARACTERISTICS
Tamb = 0 °C to +70 °C or –40 °C to +85 °C; VCC = 5 V ±10 %; VSS = 0 V (30/33 MHz max. CPU clock)
SYMBOL
PARAMETER
TEST
CONDITIONS
LIMITS
MIN
VIL
Input LOW voltage11
VIH
Input HIGH voltage (ports 0, 1, 2, 3, EA)
4.5 V < VCC < 5.5 V
RST11
UNIT
TYP1
MAX
–0.5
0.2VCC – 0.1
V
0.2VCC + 0.9
VCC + 0.5
V
VIH1
Input HIGH voltage, XTAL1,
0.7VCC
VCC + 0.5
V
VOL
Output LOW voltage, ports 1, 2, 3 8
VCC = 4.5 V; IOL = 1.6 mA2
–
0.4
V
VOL1
Output LOW voltage, port 0, ALE, PSEN 7, 8
VCC = 4.5 V; IOL = 3.2 mA2
–
0.4
V
VOH
Output HIGH voltage, ports 1, 2, 3 3
VCC = 4.5 V; IOH = –30 mA
VCC – 0.7
–
V
VOH1
Output HIGH voltage (port 0 in external bus
mode), ALE9, PSEN3
VCC = 4.5 V; IOH = –3.2 mA
VCC – 0.7
–
V
IIL
Logical 0 input current, ports 1, 2, 3
VIN = 0.4 V
–1
–50
mA
ITL
Logical 1-to-0 transition current, ports 1, 2, 36
VIN = 2.0 V; See note 4
–
–650
mA
ILI
Input leakage current, port 0
0.45 < VIN < VCC – 0.3
–
±10
mA
ICC
Power supply current
Active mode (see Note 5)
Idle mode (see Note 5)
Power-down mode or clock stopped
(see Figure 54 for conditions)
Tamb = 0 °C to 70 °C
2
30
mA
Tamb = –40 °C to +85 °C
3
50
mA
VRAM
RAM keep-alive voltage
1.2
RRST
Internal reset pull-down resistor
40
225
V
kΩ
CIO
Pin capacitance10 (except EA)
–
15
pF
NOTES:
1. Typical ratings are not guaranteed. The values listed are at room temperature, 5 V.
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 > 100 pF), the noise pulse on the ALE pin may exceed 0.8 V. 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 5 mA 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 2 V.
5. See Figures 51 through 54 for ICC test conditions and Figure 49 for ICC vs. Frequency.
12-clock mode characteristics:
Active mode (operating): ICC = 1.0 mA + 1.1 mA × FREQ.[MHz]
Active mode (reset):
ICC = 7.0 mA + 0.6 mA FREQ.[MHz]
Idle mode:
ICC = 1.0 mA + 0.22 mA FREQ.[MHz]
6. This value applies to Tamb = 0°C to +70°C. For Tamb = –40°C to +85°C, ITL = –750 µΑ.
7. Load capacitance for port 0, ALE, and PSEN = 100 pF, load capacitance for all other outputs = 80 pF.
8. Under steady state (non-transient) conditions, IOL must be externally limited as follows:
Maximum IOL per port pin:
15 mA (*NOTE: This is 85 °C specification.)
26 mA
Maximum IOL per 8-bit port:
Maximum total IOL for all outputs:
71 mA
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 25 pF. Pin capacitance of ceramic package is less than 15 pF
(except EA is 25 pF).
11. To improve noise rejection a nominal 100 ns glitch rejection circuitry has been added to the RST pin, and a nominal 15 ns glitch rejection
circuitry has been added to the INT0 and INT1 pins. Previous devices provided only an inherent 5 ns of glitch rejection.
2004 Apr 20
68
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
AC ELECTRICAL CHARACTERISTICS (12-CLOCK MODE, 5 V ±10 % OPERATION)
Tamb = 0 °C to +70 °C or –40 °C to +85 °C ; VCC = 5 V ±10 %, VSS = 0 V1,2,3,4
Symbol
Figure
Parameter
Limits
16 MHz Clock
MIN
MAX
MIN
MAX
Unit
1/tCLCL
46
Oscillator frequency
0
33
–
–
MHz
tLHLL
41
ALE pulse width
2tCLCL – 8
–
117
–
ns
tAVLL
41
Address valid to ALE LOW
tCLCL – 13
–
49.5
–
ns
tLLAX
41
Address hold after ALE LOW
tCLCL – 20
–
42.5
–
ns
tLLIV
41
ALE LOW to valid instruction in
–
4tCLCL – 35
–
215
ns
tLLPL
41
ALE LOW to PSEN LOW
tCLCL – 10
–
52.5
–
ns
tPLPH
41
PSEN pulse width
3tCLCL – 10
–
177.5
–
ns
tPLIV
41
PSEN LOW to valid instruction in
–
3tCLCL – 35
–
152.5
ns
tPXIX
41
Input instruction hold after PSEN
0
–
0
–
ns
tPXIZ
41
Input instruction float after PSEN
–
tCLCL – 10
–
52.5
ns
tAVIV
41
Address to valid instruction in
–
5tCLCL – 35
–
277.5
ns
tPLAZ
41
PSEN LOW to address float
–
10
–
10
ns
Data Memory
tRLRH
42
RD pulse width
6tCLCL – 20
–
355
–
ns
tWLWH
43
WR pulse width
6tCLCL – 20
–
355
–
ns
tRLDV
42
RD LOW to valid data in
–
5tCLCL – 35
–
277.5
ns
tRHDX
42
Data hold after RD
0
–
0
–
ns
tRHDZ
42
Data float after RD
–
2tCLCL – 10
–
115
ns
tLLDV
42
ALE LOW to valid data in
–
8tCLCL – 35
–
465
ns
tAVDV
42
Address to valid data in
–
9tCLCL – 35
–
527.5
ns
tLLWL
42, 43
ALE LOW to RD or WR LOW
3tCLCL – 15
3tCLCL + 15
172.5
202.5
ns
tAVWL
42, 43
Address valid to WR LOW or RD LOW
4tCLCL –15
–
235
–
ns
tQVWX
43
Data valid to WR transition
tCLCL – 25
–
37.5
–
ns
tWHQX
43
Data hold after WR
tCLCL – 15
–
47.5
–
ns
tQVWH
43
Data valid to WR HIGH
7tCLCL – 5
–
432.5
–
ns
tRLAZ
42
RD LOW to address float
–
0
–
0
ns
tWHLH
42, 43
RD or WR HIGH to ALE HIGH
tCLCL – 10
tCLCL + 10
52.5
72.5
ns
External Clock
tCHCX
46
High time
0.32tCLCL
tCLCL – tCLCX
–
–
ns
tCLCX
46
Low time
0.32tCLCL
tCLCL – tCHCX
–
–
ns
tCLCH
46
Rise time
–
5
–
–
ns
tCHCL
46
Fall time
–
5
–
–
ns
Shift register
tXLXL
45
Serial port clock cycle time
12tCLCL
–
750
–
ns
tQVXH
45
Output data setup to clock rising edge
10tCLCL – 25
–
600
–
ns
tXHQX
45
Output data hold after clock rising edge
2tCLCL – 15
–
110
–
ns
tXHDX
45
Input data hold after clock rising edge
0
–
0
–
ns
–
10tCLCL – 133
–
492
ns
tXHDV
45
Clock rising edge to input data
valid5
NOTES:
1. Parameters are valid over operating temperature range unless otherwise specified.
2. Load capacitance for port 0, ALE, and PSEN = 100 pF, load capacitance for all outputs = 80 pF
3. Interfacing the microcontroller to devices with float time up to 45 ns is permitted. This limited bus contention will not cause damage to port 0
drivers.
4. Parts are guaranteed by design to operate down to 0 Hz.
5. Below 16 MHz this parameter is 8tCLCL – 133.
2004 Apr 20
69
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
AC ELECTRICAL CHARACTERISTICS (12-CLOCK MODE, 2.7 V TO 5.5 V OPERATION)
Tamb = 0 °C to +70 °C or –40 °C to +85 °C ; VCC = 2.7 V to 5.5 V, VSS = 0 V1,2,3,4
Symbol
Figure
Parameter
Limits
16 MHz Clock
MIN
MAX
MIN
MAX
Unit
1/tCLCL
46
Oscillator frequency
0
16
–
–
MHz
tLHLL
41
ALE pulse width
2tCLCL – 10
–
115
–
ns
tAVLL
41
Address valid to ALE LOW
tCLCL – 15
–
47.5
–
ns
tLLAX
41
Address hold after ALE LOW
tCLCL – 25
–
37.5
–
ns
tLLIV
41
ALE LOW to valid instruction in
–
4tCLCL – 55
–
195
ns
tLLPL
41
ALE LOW to PSEN LOW
tCLCL – 15
–
47.5
–
ns
tPLPH
41
PSEN pulse width
3tCLCL – 15
–
172.5
–
ns
tPLIV
41
PSEN LOW to valid instruction in
–
3tCLCL – 55
–
132.5
ns
tPXIX
41
Input instruction hold after PSEN
0
–
0
–
ns
tPXIZ
41
Input instruction float after PSEN
–
tCLCL – 10
–
52.5
ns
tAVIV
41
Address to valid instruction in
–
5tCLCL – 50
–
262.5
ns
tPLAZ
41
PSEN LOW to address float
–
10
–
10
ns
Data Memory
tRLRH
42
RD pulse width
6tCLCL – 25
–
350
–
ns
tWLWH
43
WR pulse width
6tCLCL – 25
–
350
–
ns
tRLDV
42
RD LOW to valid data in
–
5tCLCL – 50
–
262.5
ns
tRHDX
42
Data hold after RD
0
–
0
–
ns
tRHDZ
42
Data float after RD
–
2tCLCL –20
–
105
ns
tLLDV
42
ALE LOW to valid data in
–
8tCLCL – 55
–
445
ns
tAVDV
42
Address to valid data in
–
9tCLCL – 50
–
512.5
ns
tLLWL
42, 43
ALE LOW to RD or WR LOW
3tCLCL – 20
3tCLCL +20
167.5
207.5
ns
tAVWL
42, 43
Address valid to WR LOW or RD LOW
4tCLCL – 20
–
230
–
ns
tQVWX
43
Data valid to WR transition
tCLCL – 30
–
32.5
–
ns
tWHQX
43
Data hold after WR
tCLCL – 20
–
42.5
–
ns
tQVWH
43
Data valid to WR HIGH
7tCLCL – 10
–
427.5
–
ns
tRLAZ
42
RD LOW to address float
–
0
–
0
ns
tWHLH
42, 43
RD or WR HIGH to ALE HIGH
tCLCL – 15
tCLCL +15
47.5
77.5
ns
External Clock
tCHCX
46
High time
0.32tCLCL
tCLCL – tCLCX
–
–
ns
tCLCX
46
Low time
0.32tCLCL
tCLCL – tCHCX
–
–
ns
tCLCH
46
Rise time
–
5
–
–
ns
tCHCL
46
Fall time
–
5
–
–
ns
Shift register
tXLXL
45
Serial port clock cycle time
12tCLCL
–
750
–
ns
tQVXH
45
Output data setup to clock rising edge
10tCLCL – 25
–
600
–
ns
tXHQX
45
Output data hold after clock rising edge
2tCLCL – 15
–
110
–
ns
tXHDX
45
Input data hold after clock rising edge
0
–
0
–
ns
–
10tCLCL – 133
–
492
ns
tXHDV
45
Clock rising edge to input data
valid5
NOTES:
1. Parameters are valid over operating temperature range unless otherwise specified.
2. Load capacitance for port 0, ALE, and PSEN = 100 pF, load capacitance for all outputs = 80 pF
3. Interfacing the microcontroller to devices with float time up to 45 ns is permitted. This limited bus contention will not cause damage to port 0
drivers.
4. Parts are guaranteed by design to operate down to 0 Hz.
5. Below 16 MHz this parameter is 8tCLCL – 133.
2004 Apr 20
70
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
AC ELECTRICAL CHARACTERISTICS (6-CLOCK MODE, 5 V ±10 % OPERATION)
Tamb = 0 °C to +70 °C or –40 °C to +85 °C; VCC = 5 V ±10 %, VSS = 0 V1,2,3,4,5
Symbol
Figure
Parameter
Limits
16 MHz Clock
MIN
MAX
MIN
MAX
Unit
1/tCLCL
46
Oscillator frequency
0
30
–
–
MHz
tLHLL
41
ALE pulse width
tCLCL – 8
–
54.5
–
ns
tAVLL
41
Address valid to ALE LOW
0.5tCLCL – 13
–
18.25
–
ns
tLLAX
41
Address hold after ALE LOW
0.5tCLCL – 20
–
11.25
–
ns
tLLIV
41
ALE LOW to valid instruction in
–
2tCLCL –35
–
90
ns
tLLPL
41
ALE LOW to PSEN LOW
0.5tCLCL – 10
–
21.25
–
ns
tPLPH
41
PSEN pulse width
1.5tCLCL – 10
–
83.75
–
ns
tPLIV
41
PSEN LOW to valid instruction in
–
1.5tCLCL – 35
–
58.75
ns
tPXIX
41
Input instruction hold after PSEN
0
–
0
–
ns
tPXIZ
41
Input instruction float after PSEN
–
0.5tCLCL – 10
–
21.25
ns
tAVIV
41
Address to valid instruction in
–
2.5tCLCL – 35
–
121.25
ns
tPLAZ
41
Data Memory
PSEN LOW to address float
–
10
–
10
ns
tRLRH
42
RD pulse width
3tCLCL – 20
–
167.5
–
ns
tWLWH
43
WR pulse width
3tCLCL – 20
–
167.5
–
ns
tRLDV
42
RD LOW to valid data in
–
2.5tCLCL – 35
–
121.25
ns
tRHDX
42
Data hold after RD
0
–
0
–
ns
tRHDZ
42
Data float after RD
–
tCLCL –10
–
52.5
ns
tLLDV
42
ALE LOW to valid data in
–
4tCLCL – 35
–
215
ns
tAVDV
42
Address to valid data in
–
4.5tCLCL – 35
–
246.25
ns
tLLWL
42, 43
ALE LOW to RD or WR LOW
1.5tCLCL – 15
1.5tCLCL +15
78.75
108.75
ns
tAVWL
42, 43
Address valid to WR LOW or RD LOW
2tCLCL –15
–
110
–
ns
tQVWX
43
Data valid to WR transition
0.5tCLCL – 25
–
6.25
–
ns
tWHQX
43
Data hold after WR
0.5tCLCL – 15
–
16.25
–
ns
tQVWH
43
Data valid to WR HIGH
3.5tCLCL – 5
–
213.75
–
ns
tRLAZ
42
RD LOW to address float
–
0
–
0
ns
tWHLH
42, 43
External Clock
RD or WR HIGH to ALE HIGH
0.5tCLCL – 10
0.5tCLCL +10
21.25
41.25
ns
tCHCX
46
High time
0.4tCLCL
tCLCL – tCLCX
–
–
ns
tCLCX
46
Low time
0.4tCLCL
tCLCL – tCHCX
–
–
ns
tCLCH
46
Rise time
–
5
–
–
ns
tCHCL
46
Shift register
Fall time
–
5
–
–
ns
tXLXL
45
Serial port clock cycle time
6tCLCL
–
375
–
ns
tQVXH
45
Output data setup to clock rising edge
5tCLCL –25
–
287.5
–
ns
tXHQX
45
Output data hold after clock rising edge
tCLCL – 15
–
47.5
–
ns
tXHDX
45
Input data hold after clock rising edge
0
–
0
–
ns
tXHDV
45
Clock rising edge to input data valid6
–
5tCLCL – 133
–
179.5
ns
NOTES:
1. Parameters are valid over operating temperature range unless otherwise specified.
2. Load capacitance for port 0, ALE, and PSEN=100 pF, load capacitance for all outputs = 80 pF
3. Interfacing the microcontroller to devices with float time up to 45ns is permitted. This limited bus contention will not cause damage to port 0
drivers.
4. Parts are guaranteed by design to operate down to 0 Hz.
5. Data shown in the table are the best mathematical models for the set of measured values obtained in tests. If a particular parameter
calculated at a customer specified frequency has a negative value, it should be considered equal to zero.
6. Below 16 MHz this parameter is 4tCLCL – 133
2004 Apr 20
71
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
AC ELECTRICAL CHARACTERISTICS (6-CLOCK MODE, 2.7 V TO 5.5 V OPERATION)
Tamb = 0 °C to +70 °C or –40 °C to +85 °C; VCC=2.7 V to 5.5 V, VSS = 0 V1,2,3,4,5
Symbol
Figure Parameter
Limits
Unit
16 MHz Clock
MIN
MAX
MIN
MAX
1/tCLCL
46
Oscillator frequency
0
16
–
–
MHz
tLHLL
41
ALE pulse width
tCLCL – 10
–
52.5
–
ns
tAVLL
41
Address valid to ALE LOW
0.5tCLCL – 15
–
16.25
–
ns
tLLAX
41
Address hold after ALE LOW
0.5tCLCL – 25
–
6.25
–
ns
tLLIV
41
ALE LOW to valid instruction in
–
2tCLCL –55
–
70
ns
tLLPL
41
ALE LOW to PSEN LOW
0.5tCLCL – 15
–
16.25
–
ns
tPLPH
41
PSEN pulse width
1.5tCLCL – 15
–
78.75
–
ns
tPLIV
41
PSEN LOW to valid instruction in
–
1.5tCLCL – 55
–
38.75
ns
tPXIX
41
Input instruction hold after PSEN
0
–
0
–
ns
tPXIZ
41
Input instruction float after PSEN
–
0.5tCLCL – 10
–
21.25
ns
tAVIV
41
Address to valid instruction in
–
2.5tCLCL – 50
–
101.25
ns
tPLAZ
41
Data Memory
PSEN LOW to address float
–
10
–
10
ns
tRLRH
42
RD pulse width
3tCLCL – 25
–
162.5
–
ns
tWLWH
43
WR pulse width
3tCLCL – 25
–
162.5
–
ns
tRLDV
42
RD LOW to valid data in
–
2.5tCLCL – 50
–
106.25
ns
tRHDX
42
Data hold after RD
0
–
0
–
ns
tRHDZ
42
Data float after RD
–
tCLCL – 20
–
42.5
ns
tLLDV
42
ALE LOW to valid data in
–
4tCLCL – 55
–
195
ns
tAVDV
42
Address to valid data in
–
4.5tCLCL – 50
–
231.25
ns
tLLWL
42, 43
ALE LOW to RD or WR LOW
1.5tCLCL – 20
1.5tCLCL + 20
73.75
113.75
ns
tAVWL
42, 43
Address valid to WR LOW or RD LOW
2tCLCL – 20
–
105
–
ns
tQVWX
43
Data valid to WR transition
0.5tCLCL – 30
–
1.25
–
ns
tWHQX
43
Data hold after WR
0.5tCLCL – 20
–
11.25
–
ns
tQVWH
43
Data valid to WR HIGH
3.5tCLCL – 10
–
208.75
–
ns
tRLAZ
42
RD LOW to address float
–
0
–
0
ns
tWHLH
42, 43
External Clock
RD or WR HIGH to ALE HIGH
0.5tCLCL – 15
0.5tCLCL + 15
16.25
46.25
ns
tCHCX
46
High time
0.4tCLCL
tCLCL – tCLCX
–
–
ns
tCLCX
46
Low time
0.4tCLCL
tCLCL – tCHCX
–
–
ns
tCLCH
46
Rise time
–
5
–
–
ns
tCHCL
46
Shift register
Fall time
–
5
–
–
ns
tXLXL
45
Serial port clock cycle time
6tCLCL
–
375
–
ns
tQVXH
45
Output data setup to clock rising edge
5tCLCL –25
–
287.5
–
ns
tXHQX
45
Output data hold after clock rising edge
tCLCL – 15
–
47.5
–
ns
tXHDX
45
Input data hold after clock rising edge
0
–
0
–
ns
tXHDV
45
Clock rising edge to input data valid6
2
I C interface timing
–
5tCLCL – 133
–
179.5
ns
fSCL
SCL clock frequency
0
100
0
400
kHz
tBUF
Bus free time between a STOP and START
condition
4.7
–
1.3
–
µs
tHD; STA
Hold time (repeated) START condition. After
this period, the first clock pulse is generated
4.0
–
0.6
–
µs
tLOW
LOW period of the SCL clock
4.7
–
1.3
–
µs
tHIGH
High period of the SCL clock
4.0
–
0.6
–
µs
tSU; STA
Set-up time for a repeated START condition
4.7
–
0.6
–
µs
2004 Apr 20
72
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
µs
Data hold time:
– for CBUS compatible masters
– for I2C–bus devices
5.0
0
–
–
–
0
–
0.9
tSU;DAT
Data set-up time
250
–
100
–
ns
tFD, tFC
Rise time of both SDA and SCL signals
–
1000
20 + 0.1 cb
300
ns
tFD, tFC
Fall time of both SDA and SCL signals
–
300
20 + 0.1 cb
300
ns
tSU; STO
Set-up time for STOP condition
4.0
–
0.6
–
µs
Cb
Capacitive load for each bus line
–
400
–
400
pF
tSP
Pulse width of spikes which must be suppressed by the input filter
–
–
0
50
ns
tHD;DAT
NOTES:
1. Parameters are valid over operating temperature range unless otherwise specified.
2. Load capacitance for port 0, ALE, and PSEN=100 pF, load capacitance for all outputs = 80 pF
3. Interfacing the microcontroller to devices with float time up to 45ns is permitted. This limited bus contention will not cause damage to port 0
drivers.
4. Parts are guaranteed by design to operate down to 0 Hz.
5. Data shown in the table are the best mathematical models for the set of measured values obtained in tests. If a particular parameter
calculated at a customer specified frequency has a negative value, it should be considered equal to zero.
6. Below 16 MHz this parameter is 4tCLCL – 133
2004 Apr 20
73
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 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 41. 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 42. External Data Memory Read Cycle
2004 Apr 20
74
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 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 43. External Data Memory Write Cycle
repeated START condition
START or repeated START condition
START condition
tSU;STA
STOP condition
tRD
SDA
(INPUT/OUTPUT)
0.7 VDD
0.3 VDD
tBUF
tFD
tRC
tFC
t SP
tSU; STO
0.7 VDD
SCL
(INPUT/OUTPUT)
0.3 VDD
tSU;DAT3
tHD;STA
tLOW
tHIGH
tSU;DAT1
tHD;DAT
Figure 44. Timing I2C interface
2004 Apr 20
75
tSU;DAT2
SU01742
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
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 45. Shift Register Mode Timing
VCC–0.5
0.45V
0.7VCC
0.2VCC–0.1
tCHCL
tCHCX
tCLCH
tCLCX
tCLCL
SU00009
Figure 46. External Clock Drive
VCC–0.5
VLOAD+0.1V
0.2VCC+0.9
VLOAD
0.45V
0.2VCC–0.1
VLOAD–0.1V
TIMING
REFERENCE
POINTS
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’.
SU00717
SU00718
Figure 47. AC Testing Input/Output
2004 Apr 20
VOH–0.1V
Figure 48. Float Waveform
76
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
40
35
MAX ACTIVE MODE
FREQ. + 1.0
ICCMAX = 1.1
ICC(mA)
30
25
20
15
TYP ACTIVE MODE
10
MAX IDLE MODE
ICCMAX = 0.22
FREQ. + 1.0
5
TYP IDLE MODE
4
8
12
16
20
24
28
32
36
FREQ AT XTAL1 (MHz)
SU01684
Figure 49. ICC vs. FREQ for 12-clock operation
Valid only within frequency specifications of the specified operating voltage
/*
##
as31 version V2.10
/ *js* /
##
##
##
source file: idd_ljmp1.asm
##
list file: idd_ljmp1.lst
created Fri Apr 20 15:51:40 2001
##
##########################################################
#0000
# AUXR equ 08Eh
#0000
# CKCON equ 08Fh
#
#
#0000
# org 0
#
# LJMP_LABEL:
0000 /75;/8E;/01;
#
MOV
AUXR,#001h
; turn off ALE
0003 /02;/FF;/FD;
#
LJMP
LJMP_LABEL
; jump to end of address space
0005 /00;
#
NOP
#
#FFFD
# org 0fffdh
#
# LJMP_LABEL:
#
FFFD /02;/FD;FF;
#
LJMP LJMP_LABEL
# ;
NOP
#
#
*/”
Figure 50. Source code used in measuring IDD operational
2004 Apr 20
77
SU01499
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 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 51. ICC Test Condition, Active Mode
All other pins are disconnected
VCC–0.5
Figure 52. 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 53. 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 54. ICC Test Condition, Power-down mode
All other pins are disconnected. VCC = 2 V to 5.5 V
2004 Apr 20
VCC
78
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
device. The VPP source should be well regulated and free of glitches
and overshoot.
EPROM CHARACTERISTICS
The 87C654X2 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.
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 57. The other pins are held at the
‘Verify Code Data’ levels indicated in Table 15. The contents of the
address location will be emitted on port 0. External pull-ups are
required on port 0 for this operation.
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 15 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 55 and 56. Figure 57 shows the
circuit configuration for normal program memory verification.
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.
Quick-Pulse Programming
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) = 99H
(060H) = 02H
The setup for microcontroller quick-pulse programming is shown in
Figure 55. 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.
The address of the EPROM location to be programmed is applied to
ports 1 and 2, as shown in Figure 55. 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 15 are held at the ‘Program
Code Data’ levels indicated in Table 15. The ALE/PROG is pulsed
LOW 5 times as shown in Figure 56.
Program/Verify Algorithms
Any algorithm in agreement with the conditions listed in Table 15,
and which satisfies the timing specifications, is suitable.
Security Bits
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.
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 16) 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.
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.
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
Encryption Array
64 bytes of encryption array are initially unprogrammed (all 1s).
Trademark phrase of Intel Corporation.
2004 Apr 20
79
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Table 15. EPROM Programming Modes
RST
PSEN
ALE/PROG
EA/VPP
P2.7
P2.6
P3.7
P3.6
P3.3
Read signature
MODE
1
0
1
1
0
0
0
0
X
Program code data
1
0
0*
VPP
1
0
1
1
X
Verify code data
1
0
1
1
0
0
1
1
X
Pgm encryption table
1
0
0*
VPP
1
0
1
0
X
Pgm security bit 1
1
0
0*
VPP
1
1
1
1
X
Pgm security bit 2
1
0
0*
VPP
1
1
0
0
X
Pgm security bit 3
1
0
0*
VPP
0
1
0
1
X
Program to 6-clock mode
1
0
0*
VPP
0
0
1
0
0
Verify 6-clock4
1
0
1
1
e
0
0
1
1
Verify security bits5
1
0
1
1
e
0
1
0
X
NOTES:
1. ‘0’ = Valid LOW for that pin, ‘1’ = valid HIGH for that pin.
2. VPP = 12.75 V ±0.25 V.
3. VCC = 5 V±10 % during programming and verification.
4. Bit is output on P0.4 (1 = 12x, 0 = 6x).
5. Security bit one is output on P0.7.
Security bit two is output on P0.6.
Security bit three is output on P0.3.
* 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
12.75 V. Each programming pulse is LOW for 100 µs (±10 µs) and HIGH for a minimum of 10 µs.
Table 16. 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.
2004 Apr 20
80
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
+5V
A0–A7
VCC
P1
P0
1
RST
1
P3.6
EA/VPP
1
P3.7
ALE/PROG
OTP
XTAL2
4–6MHz
XTAL1
A8–A15 are programming addresses
(not external memory addresses per
device pin out)
PGM DATA
+12.75V
5 PULSES TO GROUND
PSEN
0
P2.7
1
P2.6
0
A8–A13
P2.0–P2.5
VSS
SU01746
Figure 55. 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 56. PROG Waveform
+5V
VCC
A0–A7
P0
P1
1
RST
1
P3.6
1
P3.7
OTP
XTAL2
4–6MHz
XTAL1
A8–A15 are programming addresses
(not external memory addresses per
device pin out)
EA/VPP
1
ALE/PROG
1
PSEN
0
P2.7
0 ENABLE
P2.6
0
P2.0–P2.5
A8–A13
VSS
SU01747
Figure 57. Program Verification
2004 Apr 20
PGM DATA
81
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
EPROM PROGRAMMING AND VERIFICATION CHARACTERISTICS
Tamb = 21°C to +27°C, VCC = 5 V ±10 %, VSS = 0 V (See Figure 58)
SYMBOL
VPP
PARAMETER
Programming supply voltage
MIN
MAX
UNIT
12.5
13.0
V
50
1
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
6
110
mA
MHz
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 55.
FOR VERIFICATION CONDITIONS SEE FIGURE 57.
**
SEE TABLE 15.
Figure 58. EPROM Programming and Verification
2004 Apr 20
82
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
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 17) 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 17. 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.
2004 Apr 20
83
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
ROM CODE SUBMISSION FOR 16K ROM DEVICES
When submitting ROM code for the 16K ROM devices, the following must be specified:
1. 16 kbyte user ROM data
2. 64 byte ROM encryption key
3. ROM security bits.
ADDRESS
CONTENT
BIT(S)
COMMENT
0000H to 3FFFH
DATA
7:0
User ROM Data
4000H to 403FH
KEY
7:0
ROM Encryption Key
FFH = no encryption
4040H
SEC
0
ROM Security Bit 1
0 = enable security
1 = disable security
4040H
SEC
1
ROM Security Bit 2
0 = enable security
1 = disable security
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
2004 Apr 20
If Yes, must send key file.
84
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
PLCC44: plastic leaded chip carrier; 44 leads
2004 Apr 20
P83C654X2/P87C654X2
SOT187-2
85
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
P83C654X2/P87C654X2
LQFP44: plastic low profile quad flat package; 44 leads; body 10 x 10 x 1.4 mm
2004 Apr 20
86
SOT389-1
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
REVISION HISTORY
Rev
Date
Description
_2
20040420
Product data (9397 750 13173)
Modifications:
• Update Special Function Registers table.
• Remove P3.4 from Figures 55 and 57.
_1
2004 Apr 20
20030213
Product data (9397 750 10814)
87
P83C654X2/P87C654X2
Philips Semiconductors
Product data
80C51 8-bit microcontroller family 16 kB OTP/ROM,
P83C654X2/P87C654X2
256B RAM, low voltage (2.7 to 5.5 V), low power, high speed
(30/33 MHz)
Purchase of Philips I2C components conveys a license under the Philips’ I2C patent
to use the components in the I2C system provided the system conforms to the
I2C specifications defined by Philips. This specification can be ordered using the
code 9398 393 40011.
Data sheet status
Level
Data sheet status [1]
Product
status [2] [3]
Definitions
I
Objective data
Development
This data sheet contains data from the objective specification for product development.
Philips Semiconductors reserves the right to change the specification in any manner without notice.
II
Preliminary data
Qualification
This data sheet contains data from the preliminary specification. Supplementary data will be published
at a later date. Philips Semiconductors reserves the right to change the specification without notice, in
order to improve the design and supply the best possible product.
III
Product data
Production
This data sheet contains data from the product specification. Philips Semiconductors reserves the
right to make changes at any time in order to improve the design, manufacturing and supply. Relevant
changes will be communicated via a Customer Product/Process Change Notification (CPCN).
[1] Please consult the most recently issued data sheet before initiating or completing a design.
[2] The product status of the device(s) described in this data sheet may have changed since this data sheet was published. The latest information is available on the Internet at URL
http://www.semiconductors.philips.com.
[3] For data sheets describing multiple type numbers, the highest-level product status determines the data sheet status.
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 60134). 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 in the products—including circuits, standard cells, and/or software—described
or contained herein in order to improve design and/or performance. When the product is in full production (status ‘Production’), relevant changes will be communicated
via a Customer Product/Process Change Notification (CPCN). 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.
 Koninklijke Philips Electronics N.V. 2004
All rights reserved. Printed in U.S.A.
Contact information
For additional information please visit
http://www.semiconductors.philips.com.
Fax: +31 40 27 24825
Date of release: 04-04
For sales offices addresses send e-mail to:
[email protected].
Document order number:
2004 Apr 20
88
9397 750 13173