PHILIPS P87C552SBAA

INTEGRATED CIRCUITS
P87C552
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V),
low power
Preliminary specification
Supersedes data of 1999 Feb 04
IC20 Data Handbook
1999 Mar 30
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
DESCRIPTION
FEATURES
• 80C51 central processing unit
• 8k × 8 EPROM expandable externally to 64k bytes
• An additional 16-bit timer/counter coupled to four capture registers
The 87C552 Single-Chip 8-Bit Microcontroller is manufactured in an
advanced CMOS process and is a derivative of the 80C51
microcontroller family. The 87C552 has the same instruction set as
the 80C51.
The 87C552 contains a 8k × 8 non-volatile EPROM, a 256 × 8
read/write data memory, five 8-bit I/O ports, one 8-bit input port, two
16-bit timer/event counters (identical to the timers of the 80C51), an
additional 16-bit timer coupled to capture and compare latches, a
15-source, four-priority-level, nested interrupt structure, an 8-input
ADC, a dual DAC pulse width modulated interface, two serial
interfaces (UART and I2C-bus), a “watchdog” timer and on-chip
oscillator and timing circuits. For systems that require extra
capability, the 8xC552 can be expanded using standard TTL
compatible memories and logic.
and three compare registers
• Two standard 16-bit timer/counters
• 256 × 8 RAM, expandable externally to 64k bytes
• Capable of producing eight synchronized, timed outputs
• A 10-bit ADC with eight multiplexed analog inputs
• Fast 8-bit ADC option
• Two 8-bit resolution, pulse width modulation outputs
• Five 8-bit I/O ports plus one 8-bit input port shared with analog
In addition, the 8xC552 has two software selectable modes of power
reduction—idle mode and power-down mode. The idle mode freezes
the CPU while allowing the RAM, timers, serial ports, and interrupt
system to continue functioning. Optionally, the ADC can be operated
in Idle mode. The power-down mode saves the RAM contents but
freezes the oscillator, causing all other chip functions to be
inoperative.
inputs
• I2C-bus serial I/O port with byte oriented master and slave
functions
• On-chip watchdog timer
• Extended temperature ranges
• Full static operation – 0 to 16 MHz
• Operating voltage range: 2.7V to 5.5V (0 to 16MHz)
• Security bits:
The device also functions as an arithmetic processor having
facilities for both binary and BCD arithmetic plus bit-handling
capabilities. The instruction set consists of over 100 instructions:
49 one-byte, 45 two-byte, and 17 three-byte. With a 16MHz crystal,
58% of the instructions are executed in 0.75µs and 40% in 1.5µs.
Multiply and divide instructions require 3µs.
– OTP/EPROM – 3 bits
• Encryption array – 64 bytes
• 4 level priority interrupt
• 15 interrupt sources
• Full-duplex enhanced UART
– Framing error detection
– Automatic address recognition
• Power control modes
– Clock can be stopped and resumed
– Idle mode
– Power down mode
• Second DPTR register
• ALE inhibit for EMI reduction
• Programmable I/O pins
• Wake-up from power-down by external interrupts
• Software reset
• Power-on detect reset
• ADC charge pump disable
• ONCE mode
• ADC active in Idle mode
1999 Mar 30
P87C552
2
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
ORDERING INFORMATION
OTP/EPROM
TEMPERATURE °C AND PACKAGE
FREQ.
(MHz)
DRAWING NUMBER
P87C552SBAA
0 to +70, Plastic Leaded Chip Carrier
16
SOT188–3
PART NUMBER DERIVATION
DEVICE NUMBER (P87C552)
FREQUENCY MAX (S)
P87C552 OTP
S = 16 MHz
TEMPERATURE RANGE (B)
PACKAGE (AA)
B = 0C to 70C
AA = PLCC
F = –40C to 85C
BLOCK DIAGRAM
T0
T1
3
INT0
3
INT1
3
PWM0
VDD
3
PWM1
AVSS
AVREF ADC0-7 SDA
– +
VSS
AVDD
STADC
5
SCL
1
1
XTAL1
T0, T1
TWO 16-BIT
TIMER/EVENT
COUNTERS
XTAL2
EA
ALE
DUAL
PWM
SERIAL
I2C PORT
ADC
80C51 CORE
EXCLUDING
ROM/RAM
PSEN
3
DATA
MEMORY
512 x 8 RAM
PROGRAM
MEMORY
8k x 8
OTP/ROM
CPU
WR
8-BIT INTERNAL BUS
3
RD
16
0
AD0-7
SERIAL
UART
PORT
PARALLEL I/O
PORTS AND
EXTERNAL BUS
2
FOUR
16-BIT
CAPTURE
LATCHES
8-BIT
PORT
A8-15
3
P0
P1
P2
P3
TxD
3
RxD
1
P5
P4
CT0I-CT3I
ALTERNATE FUNCTION OF PORT 0
3
ALTERNATE FUNCTION OF PORT 3
1
ALTERNATE FUNCTION OF PORT 1
4
ALTERNATE FUNCTION OF PORT 4
2
ALTERNATE FUNCTION OF PORT 2
5
ALTERNATE FUNCTION OF PORT 5
0
T2
16-BIT
TIMER/
EVENT
COUNTERS
1
16
1
T2
RT2
T2
16-BIT
COMPARATORS
WITH
REGISTERS
T3
WATCHDOG
TIMER
COMPARATOR
OUTPUT
SELECTION
4
CMSR0-CMSR5
CMT0, CMT1
RST
EW
SU01190
1999 Mar 30
3
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
PIN CONFIGURATIONS
Plastic Leaded Chip Carrier pin functions
XTAL1
XTAL2
EA/VPP
ALE/PROG
PSEN
AVSS
AVDD
AVref+
AVref–
STADC
PWM0
PWM1
60
PLASTIC
LEADED
CHIP CARRIER
26
44
Function
P5.0/ADC0
VDD
STADC
PWM0
PWM1
EW
P4.0/CMSR0
P4.1/CMSR1
P4.2/CMSR2
P4.3/CMSR3
P4.4/CMSR4
P4.5/CMSR5
P4.6/CMT0
P4.7/CMT1
RST
P1.0/CT0I
P1.1/CT1I
P1.2/CT2I
P1.3/CT3I
P1.4/T2
P1.5/RT2
P1.6/SCL
P1.7/SDA
Pin
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
Function
P3.0/RxD
P3.1/TxD
P3.2/INT0
P3.3/INT1
P3.4/T0
P3.5/T1
P3.6/WR
P3.7/RD
NC
NC
XTAL2
XTAL1
VSS
VSS
NC
P2.0/A08
P2.1/A09
P2.2/A10
P2.3/A11
P2.4/A12
P2.5/A13
P2.6/A14
P2.7/A15
Pin
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
Function
PSEN
ALE/PROG
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
AVref–
AVref+
AVSS
AVDD
P5.7/ADC7
P5.6/ADC6
P5.5/ADC5
P5.4/ADC4
P5.3/ADC3
P5.2/ADC2
P5.1/ADC1
ADC0-7
PORT 5
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
43
CMT0
CMT1
RST
EW
CT0I
CT1I
CT2I
CT3I
T2
RT2
SCL
SDA
HIGH ORDER
ADDRESS AND
DATA BUS
RxD/DATA
TxD/CLOCK
INT0
INT1
T0
T1
WR
RD
SU00210
SU00208
1999 Mar 30
LOW ORDER
ADDRESS AND
DATA BUS
CMSR0-5
PORT 4
27
PORT 1
10
PORT 0
VSS
VDD
61
PORT 2
1
LOGIC SYMBOL
PORT 3
9
P87C552
4
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
PIN DESCRIPTION
PIN NO.
PLCC
QFP
TYPE
NAME AND FUNCTION
VDD
MNEMONIC
2
72
I
Digital Power Supply: Positive voltage power supply pin during normal operation, idle and
power-down mode.
STADC
3
74
I
Start ADC Operation: Input starting analog to digital conversion (ADC operation can also
be started by software).
PWM0
4
75
O
Pulse Width Modulation: Output 0.
PWM1
5
76
O
Pulse Width Modulation: Output 1.
Enable Watchdog Timer: Enable for T3 watchdog timer and disable power-down mode.
EW
6
77
I
P0.0-P0.7
57-50
58-51
I/O
Port 0: Port 0 is an 8-bit open-drain bidirectional I/O port. Port 0 pins that have 1s written
to them float and can be used as high-impedance inputs. Port 0 is also the multiplexed
low-order address and data bus during accesses to external program and data memory. In
this application it uses strong internal pull-ups when emitting 1s. Port 0 is also used to input
the code byte during programming and to output the code byte during verification.
P1.0-P1.7
16-23
16-21
22-23
16-19
20
21
22
23
10-17
10-15
16-17
10-13
14
15
16
17
I/O
I/O
I/O
I
I
I
I/O
I/O
Port 1: 8-bit I/O port. Alternate functions include:
(P1.0-P1.5): Programmable I/O port pins.
(P1.6, P1.7): Open drain port pins.
CT0I-CT3I (P1.0-P1.3): Capture timer input signals for timer T2.
T2 (P1.4): T2 event input.
RT2 (P1.5): T2 timer reset signal. Rising edge triggered.
SCL (P1.6): Serial port clock line I2C-bus.
SDA (P1.7): Serial port data line I2C-bus.
Port 1 has four modes selected on a per bit basis by writing to the P1M1 and P1M2
registers as follows:
P1M1.x
P1M2.x
Mode Description
0
0
Pseudo–bidirectional (standard c51 configuration; default)
0
1
Push-Pull
1
0
High impedance
1
1
Open drain
Port 1 is also used to input the lower order address byte during EPROM programming and
verification. A0 is on P1.0, etc.
P2.0-P2.7
39-46
38-42,
45-47
I/O
Port 2: 8-bit programmable I/O port.
Alternate function: High-order address byte for external memory (A08-A15). Port 2 is also
used to input the upper order address during EPROM programming and verification. A8 is
on P2.0, A9 on P2.1, through A12 on P2.4.
Port 2 has four output modes selected on a per bit basis by writing to the P2M1 and P2M2
registers as follows:
P2M1.x
P2M2.x
Mode Description
0
0
Pseudo–bidirectional (standard c51 configuration; default)
0
1
Push-Pull
1
0
High impedance
1
1
Open drain
P3.0-P3.7
24-31
18-20,
23-27
I/O
Port 3: 8-bit programmable I/O port. Alternate functions include:
24
25
26
27
28
29
30
31
18
19
20
23
24
25
26
27
RxD(P3.0): Serial input port.
TxD (P3.1): Serial output port.
INT0 (P3.2): External interrupt.
INT1 (P3.3): External interrupt.
T0 (P3.4): Timer 0 external input.
T1 (P3.5): Timer 1 external input.
WR (P3.6): External data memory write strobe.
RD (P3.7): External data memory read strobe.
Port 3 has four modes selected on a per bit basis by writing to the P3M1 and P3M2
registers as follows:
P3M1.x
0
0
1
1
1999 Mar 30
P3M2.x
0
1
0
1
5
Mode Description
Pseudo–bidirectional (standard c51 configuration; default)
Push–Pull
High impedance
Open drain
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
PIN DESCRIPTION (Continued)
PIN NO.
MNEMONIC
P4.0-P4.7
PLCC
QFP
TYPE
7-14
80, 1-2
4-8
80, 1-2
4-6
7, 8
I/O
Port 4: 8-bit programmable I/O port. Alternate functions include:
O
CMSR0-CMSR5 (P4.0-P4.5): Timer T2 compare and set/reset outputs on a match with
timer T2.
CMT0, CMT1 (P4.6, P4.7): Timer T2 compare and toggle outputs on a match with timer T2.
7-12
13, 14
O
NAME AND FUNCTION
Port 4 has four modes selected on a per bit basis by writing to the P4M1 and P4M2
registers as follows:
P4M1.x
0
0
1
1
P5.0-P5.7
P4M2.x
0
1
0
1
Mode Description
Pseudo-bidirectional (standard c51 configuration; default)
Push-Pull
High impedance
Open drain
68-62,
1
71-64
I
RST
15
9
I/O
Reset: Input to reset the 87C552. It also provides a reset pulse as output when timer T3
overflows.
XTAL1
35
32
I
Crystal Input 1: Input to the inverting amplifier that forms the oscillator, and input to the
internal clock generator. Receives the external clock signal when an external oscillator is
used.
XTAL2
34
31
O
Crystal Input 2: Output of the inverting amplifier that forms the oscillator. Left open-circuit
when an external clock is used.
36, 37
34-36
I
Digital ground.
PSEN
47
48
O
Program Store Enable: Active-low read strobe to external program memory.
ALE/PROG
48
49
O
Address Latch Enable: Latches the low byte of the address during accesses to external
memory. It is activated every six oscillator periods. During an external data memory
access, one ALE pulse is skipped. ALE can drive up to eight LS TTL inputs and handles
CMOS inputs without an external pull-up. This pin is also the program pulse input (PROG)
during EPROM programming.
EA/VPP
49
50
I
External Access: When EA is held at TTL level high, the CPU executes out of the internal
program ROM provided the program counter is less than 8,192. When EA is held at TTL
low level, the CPU executes out of external program memory. EA is not allowed to float.
This pin also receives the 12.75V programming supply voltage (VPP) during EPROM
programming.
AVREF–
58
59
I
Analog to Digital Conversion Reference Resistor: Low-end.
AVREF+
59
60
I
Analog to Digital Conversion Reference Resistor: High-end.
AVSS
60
61
I
Analog Ground
VSS
Port 5: 8-bit input port.
ADC0-ADC7 (P5.0-P5.7): Alternate function: Eight input channels to the ADC.
AVDD
61
63
I
Analog Power Supply
NOTE:
1. To avoid “latch-up” effect at power-on, the voltage on any pin at any time must not be higher or lower than VDD + 0.5V or VSS – 0.5V,
respectively.
1999 Mar 30
6
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Table 1.
SYMBOL
P87C552
87C552 Special Function Registers
DESCRIPTION
DIRECT
ADDRESS
MSB
BIT ADDRESS, SYMBOL, OR ALTERNATIVE PORT FUNCTION
E7
LSB
ACC*
Accumulator
E0H
ADCH#
A/D converter high
C6H
ADCON#
A/D control
C5H
ADC.1
ADC.0
ADEX
ADCI
ADCS
AADR2
AADR1
AADR0
xx000000B
AUXR
Auxillary
8EH
–
–
–
–
–
LVADC
–
A0
xxxxx110B
AUXR1
Auxillary
A2H
ADC8
AIDL
SRST
GF2
WUPD
O
–
DPS
000000x0B
B*
B register
F0H
F7
F6
F5
F4
F3
F2
F1
F0
00H
CTCON#
Capture control
EBH
CTN3
CTP3
CTN2
CTP2
CTN1
CTP1
CTN0
CTP0
00H
CTH3#
Capture high 3
CFH
xxxxxxxxB
CTH2#
Capture high 2
CEH
xxxxxxxxB
CTH1#
Capture high 1
CDH
xxxxxxxxB
CTH0#
Capture high 0
CCH
xxxxxxxxB
CMH2#
Compare high 2
CBH
00H
CMH1#
Compare high 1
CAH
00H
CMH0#
Compare high 0
C9H
00H
CTL3#
Capture low 3
AFH
xxxxxxxxB
CTL2#
Capture low 2
AEH
xxxxxxxxB
CTL1#
Capture low 1
ADH
xxxxxxxxB
CTL0#
Capture low 0
ACH
xxxxxxxxB
CML2#
Compare low 2
ABH
00H
CML1#
Compare low 1
AAH
00H
CML0#
Compare low 0
A9H
00H
DPTR:
DPH
DPL
Data pointer
(2 bytes):
Data pointer high
Data pointer low
83H
82H
00H
00H
IEN0*#
Interrupt enable 0
A8H
IEN1*#
Interrupt enable 1
E8H
E6
E5
E4
E3
E2
E1
E0
RESET
VALUE
00H
xxxxxxxxB
AF
AE
AD
AC
AB
AA
A9
A8
EA
EAD
ES1
ES0
ET1
EX1
ET0
EX0
EF
EE
ED
EC
EB
EA
E9
E8
ET2
ECM2
ECM1
ECM0
ECT3
ECT2
ECT1
ECT0
BF
BE
BD
BC
BB
BA
B9
B8
–
PAD
PS1
PS0
PT1
PX1
PT0
PX0
00H
00H
IP0*#
Interrupt priority 0
B8H
FF
FE
FD
FC
FB
FA
F9
F8
IP0H
Interrupt priority 0 high
B7H
–
PADH
PS1H
PS0H
PT1H
PX1H
PT0H
PX0H
x0000000B
IP1*#
Interrupt priority1
F8H
PT2
PCM2
PCM1
PCM0
PCT3
PCT2
PCT1
PCT0
00H
IP1H
Interrupt priority 1 high
F7H
PT2H
PCM2H
PCM1H
PCM0H
PCT3H
PCT2H
PCT1H
PCT0H
00H
P5#
Port 5
C4H
ADC7
ADC6
ADC5
ADC4
ADC3
ADC2
ADC1
ADC0
C7
C6
C5
C4
C3
C2
C1
C0
CMT0
CMSR5
CMSR4
CMSR3
CMSR2
CMSR1
CMSR0
P4#*
Port 4
C0H
CMT1
B7
B6
B5
B4
B3
B2
B1
B0
P3*
Port 3
B0H
RD
WR
T1
T0
INT1
INT0
TXD
RXD
A7
A6
A5
A4
A3
A2
A1
A0
A15
A14
A13
A12
A11
A10
A9
A8
97
96
95
94
93
92
91
90
SDA
SCL
RT2
T2
CT3I
CT2I
CT1I
CT0I
87
86
85
84
83
82
81
80
AD7
AD6
AD5
AD4
AD3
AD2
AD1
AD0
P2*
P1*
P0*
1999 Mar 30
Port 2
Port 1
Port 0
A0H
90H
80H
7
x0000000B
xxxxxxxxB
FFH
FFH
FFH
FFH
FFH
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
SYMBOL
DESCRIPTION
DIRECT
ADDRESS
P87C552
BIT ADDRESS, SYMBOL, OR ALTERNATIVE PORT FUNCTION
MSB
LSB
RESET
VALUE
P1M1
Port 1 output mode 1
92H
xx000000B
P1M2
Port 1 output mode 2
93H
xx000000B
P2M1
Port 2 output mode 1
94H
00H
P2M2
Port 2 output mode 2
95H
00H
P3M1
Port 3 output mode 1
9AH
00H
P3M2
Port 3 output mode 2
9BH
00H
P4M1
Port 4 output mode 1
9CH
00H
P4M2
Port 4 output mode 2
9DH
00H
PCON
Power control
87H
SMOD1
SMOD0
POF
WLE
GF1
GFO
PD
IDL
PSW
Program status word
D0H
CY
AC
FO
RS1
RS0
OV
F1
P
PWMP#
PWM prescaler
FEH
00H
PWM1#
PWM register 1
FDH
00H
PWM0#
PWM register 0
FCH
RTE#
Reset/toggle enable
EFH
S0ADDR
Serial 0 slave address
F9H
00H
S0ADEN
Slave address mask
B9H
00H
S0BUF
Serial 0 data buffer
99H
00x00000B
00H
00H
TP47
TP46
RP45
RP44
RP43
RP42
RP41
RP40
00H
xxxxxxxxB
9F
9E
9D
SM0/FE
SM1
SM2
S0CON*
Serial 0 control
98H
S1ADR#
Serial 1 address
DBH
SIDAT#
Serial 1 data
DAH
S1STA#
Serial 1 status
D9H
SC4
DF
DE
SICON#*
Serial 1 control
D8H
CR2
ENS1
SP
Stack pointer
81H
STE#
Set enable
EEH
TH1
TH0
TL1
TL0
TMH2#
TML2#
Timer high 1
Timer high 0
Timer low 1
Timer low 0
Timer high 2
Timer low 2
8DH
8CH
8BH
8AH
EDH
ECH
TMOD
Timer mode
89H
9C
9B
9A
99
REN
TB8
RB8
TI
SLAVE ADDRESS
98
RI
00H
GC
00H
00H
SC3
SC2
SC1
SC0
0
0
0
DD
DC
DB
DA
D9
D8
STA
ST0
SI
AA
CR1
CR0
F8H
00H
07H
TG47
TG46
SP45
SP44
SP43
SP42
SP41
SP40
C0H
00H
00H
00H
00H
00H
00H
GATE
C/T
M1
M0
GATE
C/T
M1
M0
8F
8E
8D
8C
8B
8A
89
88
00H
TCON*
Timer control
88H
TF1
TR1
TF0
TR0
IE1
IT1
IE0
IT0
00H
TM2CON#
Timer 2 control
EAH
T2IS1
T2IS0
T2ER
T2B0
T2P1
T2P0
T2MS1
T2MS0
00H
CF
CE
CD
CC
CB
CA
C9
C8
T20V
CMI2
CMI1
CMI0
CTI3
CTI2
CTI1
CTI0
TM2IR#*
Timer 2 int flag reg
C8H
T3#
Timer 3
FFH
00H
* SFRs are bit addressable.
# SFRs are modified from or added to the 80C51 SFRs.
1999 Mar 30
00H
8
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
OSCILLATOR CHARACTERISTICS
P87C552
VDD
XTAL1 and XTAL2 are the input and output, respectively, of an
inverting amplifier. The pins can be configured for use as an on-chip
oscillator, as shown in the logic symbol.
VDD
To drive the device from an external clock source, XTAL1 should be
driven while XTAL2 is left unconnected. There are no requirements
on the duty cycle of the external clock signal, because the input to
the internal clock circuitry is through a divide-by-two flip-flop.
However, minimum and maximum high and low times specified in
the data sheet must be observed.
+
2.2 µF
8XC552
RST
RESET
RRST
A reset is accomplished by either (1) externally holding the RST pin
high for at least two machine cycles (24 oscillator periods) or (2)
internally by an on-chip power-on detect (POD) circuit which detects
VCC ramping up from 0V.
To insure a good external power-on reset, the RST pin must be high
long enough for the oscillator to start up (normally a few
milliseconds) plus two machine cycles. The voltage on VDD and the
RST pin must come up at the same time for a proper startup.
SU01114
Figure 2. Power-On Reset
For a successful internal power-on reset, the VCC voltage must
ramp up from 0V smoothly at a ramp rate greater than 5V/100 ms.
LOW POWER MODES
The RST line can also be pulled HIGH internally by a pull-up
transistor activated by the watchdog timer T3. The length of the
output pulse from T3 is 3 machine cycles. A pulse of such short
duration is necessary in order to recover from a processor or system
fault as fast as possible.
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.
Note that the short reset pulse from Timer T3 cannot discharge the
power-on reset capacitor (see Figure 2). Consequently, when the
watchdog timer is also used to set external devices, this capacitor
arrangement should not be connected to the RST pin, and a
different circuit should be used to perform the power-on reset
operation. A timer T3 overflow, if enabled, will force a reset condition
to the 8XC554 by an internal connection, independent of the level of
the RST pin.
Idle Mode
In the idle mode (see Table 2), the CPU puts itself to sleep while
some 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.
A reset may be performed in software by setting the software reset
bit, SRST (AUXR1.5).
VDD
Power-Down Mode
To save even more power, a Power Down mode (see Table 2) can
be invoked by software. In this mode, the oscillator is stopped and
the instruction that invoked Power Down is the last instruction
executed. The on-chip RAM and Special Function Registers retain
their values down to 2.0V and care must be taken to return VCC to
the minimum specified operating voltages before the Power Down
Mode is terminated.
OVERFLOW
TIMER T3
SCHMITT
TRIGGER
RESET
CIRCUITRY
RST
ON-CHIP
RESISTOR
Either a hardware reset or external interrupt can be used to exit from
Power Down. The Wake-up from Power-down bit, WUPD (AUXR1.3)
must be set in order for an external interrupt to cause a wake-up
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.
RRST
SU00952
Figure 1. On-Chip Reset Configuration
1999 Mar 30
To properly terminate Power Down the reset or external interrupt
should not be executed before VCC is restored to its normal
operating level and must be held active long enough for the
oscillator to restart and stabilize (normally less than 10ms).
9
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
Table 2. External Pin Status During Idle and Power-Down Modes
PROGRAM
MEMORY
ALE
PSEN
PORT 0
PORT 1
PORT 2
PORT 3
PORT 4
PWM0/
PWM1
Idle
Internal
1
1
Data
Data
Data
Data
Data
High
Idle
External
1
1
Float
Data
Address
Data
Data
High
Power-down
Internal
0
0
Data
Data
Data
Data
Data
High
Power-down
External
0
0
Float
Data
Data
Data
Data
High
MODE
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.
ONCE Mode
POWER OFF FLAG
2. Hold ALE low as RST is deactivated.
The Power Off Flag (POF) is set by on-chip circuitry when the VCC
level on the 8XC552 rises from 0 to 5V. 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 powerdown. The VCC level
must remain above 3V for the POF to remain unaffected by the VCC
level.
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.
Design Consideration
The ALE-Off bit, AO (AUXR.0) can be set to disable the ALE output.
It will automatically become active when required for external
memory accesses and resume to the OFF state after completing the
external memory access.
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:
1. Pull ALE low while the device is in reset and PSEN is high;
Reduced EMI Mode
• 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.
7
PCON
(87H)
6
SMOD1 SMOD0
5
4
3
2
1
POF
WLE
GF1
GF0
PD
(MSB)
0
IDL
(LSB)
BIT
SYMBOL
FUNCTION
PCON.7
SMOD1
PCON.6
PCON.5
PCON.4
SMOD0
POF
WLE
PCON.3
PCON.2
PCON.1
PCON.0
GF1
GF0
PD
IDL
Double Baud rate bit. When set to logic 1, the baud rate is doubled when the serial port SIO0 is being
used in modes 1, 2, or 3.
Selects SM0/FE for SCON.7 bit.
Power Off Flag
Watchdog Load Enable. This flag must be set by software prior to loading timer T3 (watchdog timer). It is
cleared when timer T3 is loaded.
General-purpose flag bit.
General-purpose flag bit.
Power-down bit. Setting this bit activates the power-down mode. It can only be set if input EW is high.
Idle mode bit. Setting this bit activates the Idle mode.
If logic 1s are written to PD and IDL at the same time, PD takes precedence. The reset value of PCON is (00X00000).
SU00954
Figure 3. Power Control Register (PCON)
1999 Mar 30
10
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
AUXR
P87C552
Address = 8EH
Reset Value = xxxx x110B
Not Bit Addressable
—
—
—
—
—
LVADC
–
AO
7
6
5
4
3
2
1
0
Bit:
Symbol
Function
AO
Disable/Enable ALE
AO
Operating Mode
0
ALE is emitted at a constant rate of 1/6 the oscillator frequency.
1
ALE is active only during a MOVX or MOVC instruction.
LVADC
Enable A/D low voltage operation
LVADC
0
1
—
Operating Mode
Turns off A/D charge pump.
Turns on A/D charge pump. Required for operation below 4V.
Not implemented, reserved for future use*.
NOTE:
*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.
SU01115
Figure 4. AUXR: Auxiliary Register
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 other bits.
Dual DPTR
The dual DPTR structure (see Figure 5) 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.
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:
The DPS bit status should be saved by software when switching
between DPTR0 and DPTR1.
DPS
BIT0
AUXR1
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
DPTR1
DPTR0
DPH
(83H)
DPL
(82H)
EXTERNAL
DATA
MEMORY
SU00745A
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.
Figure 5.
1999 Mar 30
INC DPTR
11
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
AUXR1
P87C552
Address = A2H
Reset Value = 0000 00x0B
Not Bit Addressable
ADC8
AIDL
SRST
GF2
WUPD
0
—
DSP
7
6
5
4
3
2
1
0
Bit:
Symbol
Function
DPS
Data Pointer Switch—switches between DPRT0 and DPTR1.
DPS
Operating Mode
0
DPTR0
1
DPTR1
WUPD
GF2
Enable wakeup from powerdown.
General Purpose Flag—set and cleared by the user.
SRST
Software Reset
AIDL
Enables the ADC during idle mode.
ADC8
ADC Mode Switch—switches between 10-bit conversion and 8-bit conversion.
ADC8
0
1
Operating Mode
10-bit conversion (50 machine cycles)
8-bit conversion (24 machine cycles)
NOTE:
*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.
SU01081
Figure 6. AUXR1: DPTR Control Register
1999 Mar 30
12
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
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 S0CON. In the 9 bit
UART modes, mode 2 and mode 3, the Receive Interrupt flag (RI)
will be automatically set when the received byte contains either the
“Given” address or the “Broadcast” address. The 9 bit mode
requires that the 9th information bit is a 1 to indicate that the
received information is an address and not data. Automatic address
recognition is shown in Figure 9.
Enhanced UART
The UART operates in all of the usual modes that are described in
the first section of Data Handbook IC20, 80C51-Based 8-Bit
Microcontrollers. In addition the UART can perform framing error
detect by looking for missing stop bits, and automatic address
recognition. The UART also fully supports multiprocessor
communication as does the standard 80C51 UART.
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
S0CON register. The FE bit shares the S0CON.7 bit with SM0 and
the function of S0CON.7 is determined by PCON.6 (SMOD0) (see
Figure 7). If SMOD0 is set then S0CON.7 functions as FE.
S0CON.7 functions as SM0 when SMOD0 is cleared. When used as
FE S0CON.7 can only be cleared by software. Refer to Figure 8.
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.
Automatic Address Recognition
Automatic Address Recognition is a feature which allows the UART
to recognize certain addresses in the serial bit stream by using
S0CON Address = 98H
Reset Value = 0000 0000B
Bit Addressable
SM0/FE
Bit:
SM1
7
6
(SMOD0 = 0/1)*
SM2
REN
TB8
RB8
Tl
Rl
5
4
3
2
1
0
Symbol
Function
FE
Framing Error bit. This bit is set by the receiver when an invalid stop bit is detected. The FE bit is not cleared by valid
frames but should be cleared by software. The SMOD0 bit must be set to enable access to the FE bit.
SM0
Serial Port Mode Bit 0, (SMOD0 must = 0 to access bit SM0)
SM1
Serial Port Mode Bit 1
SM0
SM1
Mode
0
0
1
1
0
1
0
1
0
1
2
3
Description
Baud Rate**
shift register
8-bit UART
9-bit UART
9-bit UART
fOSC/12
variable
fOSC/64 or fOSC/32
variable
SM2
Enables the Automatic Address Recognition feature in Modes 2 or 3. If SM2 = 1 then Rl will not be set unless the
received 9th data bit (RB8) is 1, indicating an address, and the received byte is a Given or Broadcast Address.
In Mode 1, if SM2 = 1 then Rl will not be activated unless a valid stop bit was received, and the received byte is a
Given or Broadcast Address. In Mode 0, SM2 should be 0.
REN
Enables serial reception. Set by software to enable reception. Clear by software to disable reception.
TB8
The 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software as desired.
RB8
In modes 2 and 3, the 9th data bit that was received. In Mode 1, if SM2 = 0, RB8 is the stop bit that was received.
In Mode 0, RB8 is not used.
Tl
Transmit interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or at the beginning of the stop bit in the
other modes, in any serial transmission. Must be cleared by software.
Rl
Receive interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or halfway through the stop bit time in
the other modes, in any serial reception (except see SM2). Must be cleared by software.
NOTE:
*SMOD0 is located at PCON6.
**fOSC = oscillator frequency
SU00981
Figure 7. S0CON: Serial Port Control Register
1999 Mar 30
13
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
D0
D1
D2
D3
D4
D5
P87C552
D6
D7
D8
DATA BYTE
START
BIT
ONLY IN
MODE 2, 3
STOP
BIT
SET FE BIT IF STOP BIT IS 0 (FRAMING ERROR)
SM0 TO UART MODE CONTROL
SM0 / FE
SM1
SM2
REN
SMOD1
SMOD0
POF
WLE
TB8
GF1
RB8
TI
GF0
PD
RI
SCON
(98H)
IDL
PCON
(87H)
0 : S0CON.7 = SM0
1 : S0CON.7 = FE
SU00982
Figure 8. UART Framing Error Detection
D0
D1
D2
D3
D4
SM0
SM1
1
1
1
0
D5
SM2
1
D6
D7
D8
REN
TB8
RB8
1
X
TI
RI
SCON
(98H)
RECEIVED ADDRESS D0 TO D7
COMPARATOR
PROGRAMMED ADDRESS
IN UART MODE 2 OR MODE 3 AND SM2 = 1:
INTERRUPT IF REN=1, RB8=1 AND “RECEIVED ADDRESS” = “PROGRAMMED ADDRESS”
– WHEN OWN ADDRESS RECEIVED, CLEAR SM2 TO RECEIVE DATA BYTES
– WHEN ALL DATA BYTES HAVE BEEN RECEIVED: SET SM2 TO WAIT FOR NEXT ADDRESS.
SU00045
Figure 9. UART Multiprocessor Communication, Automatic Address Recognition
Mode 0 is the Shift Register mode and SM2 is ignored.
Slave 1
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:
Slave 0
1999 Mar 30
SADDR =
SADEN =
Given
=
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.
1100 0000
1111 1101
1100 00X0
14
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Either or both of these overflows can be programmed to request an
interrupt. In both cases, the interrupt vector will be the same. When
the lower byte (TML2) overflows, flag T2B0 (TM2CON) is set and
flag T20V (TM2IR) is set when TMH2 overflows. These flags are set
one cycle after an overflow occurs. Note that when T20V is set,
T2B0 will also be set. To enable the byte overflow interrupt, bits ET2
(IEN1.7, enable overflow interrupt, see Figure 10) and T2IS0
(TM2CON.6, byte overflow interrupt select) must be set. Bit TWB0
(TM2CON.4) is the Timer T2 byte overflow flag.
In a more complex system the following could be used to select
slaves 1 and 2 while excluding slave 0:
Slave 0
SADDR =
SADEN =
Given
=
1100 0000
1111 1001
1100 0XX0
Slave 1
SADDR =
SADEN =
Given
=
1110 0000
1111 1010
1110 0X0X
Slave 2
SADDR =
SADEN =
Given
=
1110 0000
1111 1100
1110 00XX
To enable the 16-bit overflow interrupt, bits ET2 (IE1.7, enable
overflow interrupt) and T2IS1 (TM2CON.7, 16-bit overflow interrupt
select) must be set. Bit T2OV (TM2IR.7) is the Timer T2 16-bit
overflow flag. All interrupt flags must be reset by software. To enable
both byte and 16-bit overflow, T2IS0 and T2IS1 must be set and two
interrupt service routines are required. A test on the overflow flags
indicates which routine must be executed. For each routine, only the
corresponding overflow flag must be cleared.
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.
Timer T2 may be reset by a rising edge on RT2 (P1.5) if the Timer
T2 external reset enable bit (T2ER) in T2CON is set. This reset also
clears the prescaler. In the idle mode, the timer/counter and
prescaler are reset and halted. Timer T2 is controlled by the
TM2CON special function register (see Figure 11).
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.
Timer T2 Extension: When a 12MHz oscillator is used, a 16-bit
overflow on Timer T2 occurs every 65.5, 131, 262, or 524 ms,
depending on the prescaler division ratio; i.e., the maximum cycle
time is approximately 0.5 seconds. In applications where cycle times
are greater than 0.5 seconds, it is necessary to extend Timer T2.
This is achieved by selecting fosc/12 as the clock source (set
T2MS0, reset T2MS1), setting the prescaler division ration to 1/8
(set T2P0, set T2P1), disabling the byte overflow interrupt (reset
T2IS0) and enabling the 16-bit overflow interrupt (set T2IS1). The
following software routine is written for a three-byte extension which
gives a maximum cycle time of approximately 2400 hours.
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.
Timer T2
Timer T2 is a 16-bit timer consisting of two registers TMH2 (HIGH
byte) and TML2 (LOW byte). The 16-bit timer/counter can be
switched off or clocked via a prescaler from one of two sources:
fOSC/12 or an external signal. When Timer T2 is configured as a
counter, the prescaler is clocked by an external signal on T2 (P1.4).
A rising edge on T2 increments the prescaler, and the maximum
repetition rate is one count per machine cycle (1MHz with a 12MHz
oscillator).
OVINT: PUSH
PUSH
INC
The maximum repetition rate for Timer T2 is twice the maximum
repetition rate for Timer 0 and Timer 1. T2 (P1.4) is sampled at
S2P1 and again at S5P1 (i.e., twice per machine cycle). A rising
edge is detected when T2 is LOW during one sample and HIGH
during the next sample. To ensure that a rising edge is detected, the
input signal must be LOW for at least 1/2 cycle and then HIGH for at
least 1/2 cycle. If a rising edge is detected before the end of S2P1,
the timer will be incremented during the following cycle; otherwise it
will be incremented one cycle later. The prescaler has a
programmable division factor of 1, 2, 4, or 8 and is cleared if its
division factor or input source is changed, or if the timer/counter is
reset.
ACC
PSW
TIMEX1
;save accumulator
;save status
;increment first byte (low order)
;of extended timer
MOV
JNZ
A,TIMEX1
INTEX
;jump to INTEX if ;there is no overflow
INC
MOV
JNZ
INC
TIMEX2 ;increment second byte
A,TIMEX2
INTEX
;jump to INTEX if there is no overflow
TIMEX3 ;increment third byte (high order)
INTEX: CLR
POP
POP
RETI
T2OV
PSW
ACC
;reset interrupt flag
;restore status
;restore accumulator
;return from interrupt
Timer T2, Capture and Compare Logic: Timer T2 is connected to
four 16-bit capture registers and three 16-bit compare registers. A
capture register may be used to capture the contents of Timer T2
when a transition occurs on its corresponding input pin. A compare
register may be used to set, reset, or toggle port 4 output pins at
certain pre-programmable time intervals.
Timer T2 may be read “on the fly” but possesses no extra read
latches, and software precautions may have to be taken to avoid
misinterpretation in the event of an overflow from least to most
significant byte while Timer T2 is being read. Timer T2 is not
loadable and is reset by the RST signal or by a rising edge on the
input signal RT2, if enabled. RT2 is enabled by setting bit T2ER
(TM2CON.5).
The combination of Timer T2 and the capture and compare logic is
very powerful in applications involving rotating machinery,
automotive injection systems, etc. Timer T2 and the capture and
compare logic are shown in Figure 12.
When the least significant byte of the timer overflows or when a
16-bit overflow occurs, an interrupt request may be generated.
1999 Mar 30
P87C552
15
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
IEN1 (E8H)
P87C552
7
6
5
4
3
2
1
0
ET2
ECM2
ECM1
ECM0
ECT3
ECT2
ECT1
ECT0
(MSB)
Reset Value = 00H
(LSB)
BIT
SYMBOL
FUNCTION
IEN1.7
IEN1.6
IEN1.5
IEN1.4
IEN1.3
IEN1.2
IEN1.1
IEN1.0
ET2
ECM2
ECM1
ECM0
ECT3
ECT2
ECT1
ECT0
Enable Timer T2 overflow interrupt(s)
Enable T2 Comparator 2 interrupt
Enable T2 Comparator 1 interrupt
Enable T2 Comparator 0 interrupt
Enable T2 Capture register 3 interrupt
Enable T2 Capture register 2 interrupt
Enable T2 Capture register 1 interrupt
Enable T2 Capture register 0 interrupt
SU01083
Figure 10. Timer T2 Interrupt Enable Register (IEN1)
TM2CON (EAH)
7
6
5
4
3
2
1
0
T2IS1
T2IS0
T2ER
T2BO
T2P1
T2P0
T2MS1
T2MS0
(MSB)
(LSB)
BIT
TM2CON.7
TM2CON.6
TM2CON.5
SYMBOL
TSIS1
T2IS0
T2ER
TM2CON.4
TM2CON.3
TM2CON.2
T2BO
T2P1
T2P0
T2P1
0
0
1
1
TM2CON.1
TM2CON.0
Reset Value = 00H
T2MS1
T2MS0
FUNCTION
Timer T2 16-bit overflow interrupt select
Timer T2 byte overflow interrupt select
Timer T2 external reset enable. When this bit is set,
Timer T2 may be reset by a rising edge on RT2 (P1.5).
Timer T2 byte overflow interrupt flag
Timer T2 prescaler select
T2P0
0
1
0
1
Timer T2 mode select
T2MS1 T2MS0
0
0
1
1
Timer T2 Clock
Clock source
Clock source/2
Clock source/4
Clock source/8
0
1
0
1
Mode Selected
Timer T2 halted (off)
T2 clock source = fOSC/12
Test mode; do not use
T2 clock source = pin T2
SU01084
Figure 11. T2 Control Register (TM2CON)
1999 Mar 30
16
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
CT0I
INT
INT
CT1I
CTI0
P87C552
INT
CT2I
CTI1
CT0
INT
CT3I
CTI2
CT1
CTI3
CT2
CT3
off
8-bit overflow interrupt
fosc
Prescaler
1/12
T2 Counter
16-bit overflow interrupt
T2
RT2
T2ER
External reset
enable
COMP
S
R
P4.0
S
R
P4.1
S
R
P4.2
S
R
P4.3
S
R
P4.4
S
R
P4.5
TG
T
P4.6
TG
T
P4.7
STE
RTE
CMO (S)
INT
COMP
INT
CM1 (R)
COMP
INT
CM2 (T)
I/O port 4
S
=
set
R
=
reset
T
=
toggle
TG =
T2 SFR address:
TML2
=
lower 8 bits
TMH2
=
higher 8 bits
toggle status
SU00757
Figure 12. Block Diagram of Timer 2
can be measured using Timer T2 and a capture register. When an
event occurs, the contents of Timer T2 are copied into the relevant
capture register and an interrupt request is generated. The interrupt
service routine may then compute the interval time if it knows the
previous contents of Timer T2 when the last event occurred. With a
12MHz oscillator, Timer T2 can be programmed to overflow every
524ms. When event interval times are shorter than this, computing
the interval time is simple, and the interrupt service routine is short.
For longer interval times, the Timer T2 extension routine may be
used.
Capture Logic: The four 16-bit capture registers that Timer T2 is
connected to are: CT0, CT1, CT2, and CT3. These registers are
loaded with the contents of Timer T2, and an interrupt is requested
upon receipt of the input signals CT0I, CT1I, CT2I, or CT3I. These
input signals are shared with port 1. The four interrupt flags are in
the Timer T2 interrupt register (TM2IR special function register). If
the capture facility is not required, these inputs can be regarded as
additional external interrupt inputs.
Using the capture control register CTCON (see Figure 13), these
inputs may capture on a rising edge, a falling edge, or on either a
rising or falling edge. The inputs are sampled during S1P1 of each
cycle. When a selected edge is detected, the contents of Timer T2
are captured at the end of the cycle.
Compare Logic: Each time Timer T2 is incremented, the contents
of the three 16-bit compare registers CM0, CM1, and CM2 are
compared with the new counter value of Timer T2. When a match is
found, the corresponding interrupt flag in TM2IR is set at the end of
the following cycle. When a match with CM0 occurs, the controller
sets bits 0-5 of port 4 if the corresponding bits of the set enable
register STE are at logic 1.
Measuring Time Intervals Using Capture Registers: When a
recurring external event is represented in the form of rising or falling
edges on one of the four capture pins, the time between two events
1999 Mar 30
17
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
CTCON (EBH)
P87C552
7
6
5
4
3
2
1
0
CTN3
CTP3
CTN2
CTP2
CTN1
CTP1
CTN1
CTP0
(MSB)
(LSB)
BIT
SYMBOL
CAPTURE/INTERRUPT ON:
CTCON.7
CTCON.6
CTCON.5
CTCON.4
CTCON.3
CTCON.2
CTCON.1
CTCON.0
CTN3
CTP3
CTN2
CTP2
CTN1
CTP1
CTN0
CTP0
Capture Register 3 triggered by a falling edge on CT3I
Capture Register 3 triggered by a rising edge on CT3I
Capture Register 2 triggered by a falling edge on CT2I
Capture Register 2 triggered by a rising edge on CT2I
Capture Register 1 triggered by a falling edge on CT1I
Capture Register 1 triggered by a rising edge on CT1I
Capture Register 0 triggered by a falling edge on CT0I
Capture Register 0 triggered by a rising edge on CT0I
Figure 13.
Timer T2 Interrupt Flag Register TM2IR: Eight of the nine Timer
T2 interrupt flags are located in special function register TM2IR (see
Figure 16). The ninth flag is TM2CON.4.
The CT0I and CT1I flags are set during S4 of the cycle in which the
contents of Timer T2 are captured. CT0I is scanned by the interrupt
logic during S2, and CT1I is scanned during S3. CT2I and CT3I are
set during S6 and are scanned during S4 and S5. The associated
interrupt requests are recognized during the following cycle. If these
flags are polled, a transition at CT0I or CT1I will be recognized one
cycle before a transition on CT2I or CT3I since registers are read
during S5. The CMI0, CMI1, and CMI2 flags are set during S6 of the
cycle following a match. CMI0 is scanned by the interrupt logic
during S2; CMI1 and CMI2 are scanned during S3 and S4. A match
will be recognized by the interrupt logic (or by polling the flags) two
cycles after the match takes place.
Thus, if the current operation is “set,” the next operation will be
“reset” even if the port latch is reset by software before the “reset”
operation occurs. The first “toggle” after a chip RESET will set the
port latch. The contents of these two flip-flops can be read at STE.6
and STE.7 (corresponding to P4.6 and P4.7, respectively). Bits
STE.6 and STE.7 are read only (see Figure 15 for STE register
function). A logic 1 indicates that the next toggle will set the port
latch; a logic 0 indicates that the next toggle will reset the port latch.
CM0, CM1, and CM2 are reset by the RST signal.
The 16-bit overflow flag (T2OV) and the byte overflow flag (T2BO)
are set during S6 of the cycle in which the overflow occurs. These
flags are recognized by the interrupt logic during the next cycle.
The modified port latch information appears at the port pin during
S5P1 of the cycle following the cycle in which a match occurred. If
the port is modified by software, the outputs change during S1P1 of
the following cycle. Each port 4 bit can be set or reset by software at
any time. A hardware modification resulting from a comparator
match takes precedence over a software modification in the same
cycle. When the comparator results require a “set” and a “reset” at
the same time, the port latch will be reset.
Special function register IP1 (Figure 16) is used to determine the
Timer T2 interrupt priority. Setting a bit high gives that function a
high priority, and setting a bit low gives the function a low priority.
The functions controlled by the various bits of the IP1 register are
shown in Figure 16.
7
6
5
4
3
2
1
TP47
TP46
RP45
RP44
RP43
RP42
RO41
(MSB)
0
Reset Value = 00H
RP40
(LSB)
BIT
SYMBOL
FUNCTION
RTE.7
RTE.6
RTE.5
RTE.4
RTE.3
RTE.2
RTE.1
RTE.0
TP47
TP46
RP45
RP44
RP43
RP42
RP41
RP40
If “1” then P4.7 toggles on a match between CM1 and Timer T2
If “1” then P4.6 toggles on a match between CM1 and Timer T2
If “1” then P4.5 is reset on a match between CM1 and Timer T2
If “1” then P4.4 is reset on a match between CM1 and Timer T2
If “1” then P4.3 is reset on a match between CM1 and Timer T2
If “1” then P4.2 is reset on a match between CM1 and Timer T2
If “1” then P4.1 is reset on a match between CM1 and Timer T2
If “1” then P4.0 is reset on a match between CM1 and Timer T2
Figure 14.
1999 Mar 30
SU01085
Capture Control Register (CTCON)
When a match with CM1 occurs, the controller resets bits 0-5 of port
4 if the corresponding bits of the reset/toggle enable register RTE
are at logic 1 (see Figure 14 for RTE register function). If RTE is “0”,
then P4.n is not affected by a match between CM1 or CM2 and
Timer 2. When a match with CM2 occurs, the controller “toggles”
bits 6 and 7 of port 4 if the corresponding bits of the RTE are at
logic 1. The port latches of bits 6 and 7 are not toggled.
Two additional flip-flops store the last operation, and it is these
flip-flops that are toggled.
RTE (EFH)
Reset Value = 00H
Reset/Toggle Enable Register (RTE)
18
SU01086
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
STE (EEH)
P87C552
7
6
5
4
3
2
1
TG47
TG46
SP45
SP44
SP43
SP42
SP41
(MSB)
0
Reset Value = C0H
SP40
(LSB)
BIT
SYMBOL
FUNCTION
STE.7
STE.6
STE.5
STE.4
STE.3
STE.2
STE.1
STE.0
TG47
TG46
SP45
SP44
SP43
SP42
SP41
SP40
Toggle flip-flops
Toggle flip-flops
If “1” then P4.5 is set on a match between CM0 and Timer T2
If “1” then P4.4 is set on a match between CM0 and Timer T2
If “1” then P4.3 is set on a match between CM0 and Timer T2
If “1” then P4.2 is set on a match between CM0 and Timer T2
If “1” then P4.1 is set on a match between CM0 and Timer T2
If “1” then P4.0 is set on a match between CM0 and Timer T2
SU01087
Figure 15. Set Enable Register (STE)
TM2IR (C8H)
7
6
5
4
3
2
1
0
T2OV
CMI2
CMI1
CMI0
CTI3
CTI2
CTI1
CTI0
(MSB)
Reset Value = 00H
(LSB)
BIT
SYMBOL
FUNCTION
TM2IR.7
TM2IR.6
TM2IR.5
TM2IR.4
TM2IR.3
TM2IR.2
TM2IR.1
TM2IR.0
T2OV
CMI2
CMI1
CMI0
CTI3
CTI2
CTI1
CTI0
Timer T2 16-bit overflow interrupt flag
CM2 interrupt flag
CM1 interrupt flag
CM0 interrupt flag
CT3 interrupt flag
CT2 interrupt flag
CT1 interrupt flag
CT0 interrupt flag
Interrupt Flag Register (TM2IR)
IP1 (F8H)
7
6
5
4
3
2
1
PT2
PCM2
PCM1
PCM0
PCT3
PCT2
PCT1
(MSB)
0
PCT0
(LSB)
BIT
SYMBOL
FUNCTION
IP1.7
IP1.6
IP1.5
IP1.4
IP1.3
IP1.2
IP1.1
IP1.0
PT2
PCM2
PCM1
PCM0
PCT3
PCT2
PCT1
PCT0
Timer T2 overflow interrupt(s) priority level
Timer T2 comparator 2 interrupt priority level
Timer T2 comparator 1 interrupt priority level
Timer T2 comparator 0 interrupt priority level
Timer T2 capture register 3 interrupt priority level
Timer T2 capture register 2 interrupt priority level
Timer T2 capture register 1 interrupt priority level
Timer T2 capture register 0 interrupt priority level
Timer 2 Interrupt Priority Register (IP1)
Figure 16. Interrupt Flag Register (TM2IR) and Timer T2 Interrupt Priority Register (IP1)
1999 Mar 30
Reset Value = 00H
19
SU01088
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Timer T3, The Watchdog Timer
In addition to Timer T2 and the standard timers, a watchdog timer is
also incorporated on the 8xC552. The purpose of a watchdog timer
is to reset the microcontroller if it enters erroneous processor states
(possibly caused by electrical noise or RFI) within a reasonable
period of time. An analogy is the “dead man’s handle” in railway
locomotives. When enabled, the watchdog circuitry will generate a
system reset if the user program fails to reload the watchdog timer
within a specified length of time known as the “watchdog interval.”
P87C552
In order to prepare software for watchdog operation, a programmer
should first determine how long his system can sustain an
erroneous processor state. The result will be the maximum
watchdog interval. As the maximum watchdog interval becomes
shorter, it becomes more difficult for the programmer to ensure that
the user program always reloads the watchdog timer within the
watchdog interval, and thus it becomes more difficult to implement
watchdog operation.
The programmer must now partition the software in such a way that
reloading of the watchdog is carried out in accordance with the above
requirements. The programmer must determine the execution times
of all software modules. The effect of possible conditional branches,
subroutines, external and internal interrupts must all be taken into
account. Since it may be very difficult to evaluate the execution
times of some sections of code, the programmer should use worst
case estimations. In any event, the programmer must make sure
that the watchdog is not activated during normal operation.
Watchdog Circuit Description: The watchdog timer (Timer T3)
consists of an 8-bit timer with an 11-bit prescaler as shown in
Figure 17. The prescaler is fed with a signal whose frequency is
1/12 the oscillator frequency (1MHz with a 12MHz oscillator). The
8-bit timer is incremented every “t” seconds, where:
t = 12 × 2048 × 1/fOSC
(= 1.5ms at fOSC = 16MHz)
If the 8-bit timer overflows, a short internal reset pulse is generated
which will reset the 8xC552. A short output reset pulse is also
generated at the RST pin. This short output pulse (3 machine
cycles) may be destroyed if the RST pin is connected to a capacitor.
This would not, however, affect the internal reset operation.
The watchdog timer is reloaded in two stages in order to prevent
erroneous software from reloading the watchdog. First PCON.4
(WLE) must be set. The T3 may be loaded. When T3 is loaded,
PCON.4 (WLE) is automatically reset. T3 cannot be loaded if
PCON.4 (WLE) is reset. Reload code may be put in a subroutine as
it is called frequently. Since Timer T3 is an up-counter, a reload
value of 00H gives the maximum watchdog interval (510ms with a
12MHz oscillator), and a reload value of 0FFH gives the minimum
watchdog interval (2ms with a 12MHz oscillator).
Watchdog operation is activated when external pin EW is tied low.
When EW is tied low, it is impossible to disable the watchdog
operation by software.
How to Operate the Watchdog Timer: The watchdog timer has to
be reloaded within periods that are shorter than the programmed
watchdog interval; otherwise the watchdog timer will overflow and a
system reset will be generated. The user program must therefore
continually execute sections of code which reload the watchdog
timer. The period of time elapsed between execution of these
sections of code must never exceed the watchdog interval. When
using a 16MHz oscillator, the watchdog interval is programmable
between 1.5ms and 392ms.
In the idle mode, the watchdog circuitry remains active. When
watchdog operation is implemented, the power-down mode cannot
be used since both states are contradictory. Thus, when watchdog
operation is enabled by tying external pin EW low, it is impossible to
enter the power-down mode, and an attempt to set the power-down
bit (PCON.1) will have no effect. PCON.1 will remain at logic 0.
INTERNAL BUS
VDD
fOSC/12
OVERFLOW
PRESCALER (11-BIT)
CLEAR
P
TIMER T3 (8-BIT)
LOAD LOADEN
RST
INTERNAL
RESET
WRITE T3
RRST
CLEAR
WLE
PD
LOADEN
PCON.4
PCON.1
EW
INTERNAL BUS
SU00955
Figure 17. Watchdog Timer
1999 Mar 30
20
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Buffered PWM outputs may be used to drive DC motors. The
rotation speed of the motor would be proportional to the contents of
PWMn. The PWM outputs may also be configured as a dual DAC. In
this application, the PWM outputs must be integrated using
conventional operational amplifier circuitry. If the resulting output
voltages have to be accurate, external buffers with their own analog
supply should be used to buffer the PWM outputs before they are
integrated. The repetition frequency fPWM, at the PWMn outputs is
give by:
During the early stages of software development/debugging, the
watchdog may be disabled by tying the EW pin high. At a later
stage, EW may be tied low to complete the debugging process.
Watchdog Software Example: The following example shows how
watchdog operation might be handled in a user program.
;at the program start:
T3
EQU 0FFH ;address of watchdog timer T3
PCON
EQU 087H ;address of PCON SFR
WATCH-INTV EQU 156 ;watchdog interval (e.g., 2x100ms)
f PWM ;to be inserted at each watchdog reload location within
;the user program:
f OSC
2 (1 PWMP) 255
This gives a repetition frequency range of 123Hz to 31.4kHz (fOSC =
16MHz). By loading the PWM registers with either 00H or FFH, the
PWM channels will output a constant HIGH or LOW level,
respectively. Since the 8-bit counter counts modulo 255, it can never
actually reach the value of the PWM registers when they are loaded
with FFH.
LCALL WATCHDOG
;watchdog service routine:
WATCHDOG: ORL PCON,#10H ;set condition flag (PCON.4)
MOV T3,WATCH-INV
;load T3 with watchdog interval
RET
When a compare register (PWM0 or PWM1) is loaded with a new
value, the associated output is updated immediately. It does not
have to wait until the end of the current counter period. Both PWMn
output pins are driven by push-pull drivers. These pins are not used
for any other purpose.
If it is possible for this subroutine to be called in an erroneous state,
then the condition flag WLE should be set at different parts of the
main program.
Serial I/O
The 8xC552 is equipped with two independent serial ports: SIO0
and SIO1. SIO0 is a full duplex UART port and is similar to the
Enhanced UART serial port. SIO1 accommodates the I2C bus.
Prescaler frequency control register PWMP
PWMP (FEH)
7
6
5
4
3
Reset Value = 00H
2
1
MSB
SIO0: SIO0 is a full duplex serial I/O port identical to that of the
Enhanced UART except Time 2 cannot be used as a baud rate
generator. Its operation is the same, including the use of timer 1 as a
baud rate generator.
PWMP.0-7
0
LSB
Prescaler division factor = PWMP + 1.
Reading PWMP gives the current reload value. The actual count of
the prescaler cannot be read.
Reset Value = 00H
Port 5 Operation
Port 5 may be used to input up to 8 analog signals to the ADC.
Unused ADC inputs may be used to input digital inputs. These
inputs have an inherent hysteresis to prevent the input logic from
drawing excessive current from the power lines when driven by
analog signals. Channel to channel crosstalk (Ct) should be taken
into consideration when both analog and digital signals are
simultaneously input to Port 5 (see, D.C. characteristics in data
sheet).
PWM0 (FCH)
PWM1 (FDH)
7
6
5
4
3
2
1
MSB
PWM0/1.0-7} Low/high ratio of PWMn 0
LSB
(PWMn)
255 (PWMn)
Analog-to-Digital Converter
The analog input circuitry consists of an 8-input analog multiplexer
and a 10-bit, straight binary, successive approximation ADC. The
A/D can also be operated in 8-bit mode with faster conversion times
by setting bit ADC8 (AUXR1.7). The 8-bit results will be contained in
the ADCH register. The analog reference voltage and analog power
supplies are connected via separate input pins. For 10-bit accuracy,
the conversion takes 50 machine cycles, i.e., 37.5µs at an oscillator
frequency of 16MHz. For the 8-bit mode, the conversion takes 24
machine cycles. Input voltage swing is from 0V to +5V. Because the
internal DAC employs a ratiometric potentiometer, there are no
discontinuities in the converter characteristic. Figure 19 shows a
functional diagram of the analog input circuitry.
Port 5 is not bidirectional and may not be configured as an output
port. All six ports are multifunctional, and their alternate functions
are listed in the Pin Descriptions section of this datasheet.
Pulse Width Modulated Outputs
The 8xC552 contains two pulse width modulated output channels
(see Figure 18). These channels generate pulses of programmable
length and interval. The repetition frequency is defined by an 8-bit
prescaler PWMP, which supplies the clock for the counter. The
prescaler and counter are common to both PWM channels. The 8-bit
counter counts modulo 255, i.e., from 0 to 254 inclusive. The value
of the 8-bit counter is compared to the contents of two registers:
PWM0 and PWM1. Provided the contents of either of these registers
is greater than the counter value, the corresponding PWM0 or
PWM1 output is set LOW. If the contents of these registers are
equal to, or less than the counter value, the output will be HIGH. The
pulse-width-ratio is therefore defined by the contents of the registers
PWM0 and PWM1. The pulse-width-ratio is in the range of 0 to 1
and may be programmed in increments of 1/255.
1999 Mar 30
P87C552
The ADC has the option of either being powered off in idle mode for
reduced power consumption or being active in idle mode for
reducing internal noise during the conversion. This option is selected
by the AIDL bit of AUXR1 register (AUXR1.6). With the AIDL bit set,
the ADC is active in the idle mode, and with the AIDL bit cleared, the
ADC is powered off in idle mode.
21
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
PWM0
8-BIT COMPARATOR
OUTPUT
BUFFER
PWM0
OUTPUT
BUFFER
PWM1
INTERNAL BUS
fOSC
1/2
PRESCALER
8-BIT COUNTER
PWMP
8-BIT COMPARATOR
PWM1
SU00956
Figure 18. Functional Diagram of Pulse Width Modulated Outputs
STADC
ADC0
+
ADC1
ANALOG REF.
ADC2
ADC3
ADC4
–
ANALOG INPUT
MULTIPLEXER
10-BIT A/D CONVERTER
ANALOG SUPPLY
ADC5
ADC6
ANALOG GROUND
ADC7
ADCON
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
ADCH
INTERNAL BUS
SU00957
Figure 19. Functional Diagram of Analog Input Circuitry
The software only start mode is selected when control bit ADCON.5
(ADEX) = 0. A conversion is then started by setting control bit
ADCON.3 (ADCS). The hardware or software start mode is selected
when ADCON.5 = 1, and a conversion may be started by setting
ADCON.3 as above or by applying a rising edge to external pin
STADC. When a conversion is started by applying a rising edge, a
low level must be applied to STADC for at least one machine cycle
followed by a high level for at least one machine cycle.
10-Bit Analog-to-Digital Conversion: Figure 20 shows the
elements of a successive approximation (SA) ADC. The ADC
contains a DAC which converts the contents of a successive
approximation register to a voltage (VDAC) which is compared to
the analog input voltage (Vin). The output of the comparator is fed to
the successive approximation control logic which controls the
successive approximation register. A conversion is initiated by
setting ADCS in the ADCON register. ADCS can be set by software
only or by either hardware or software.
1999 Mar 30
22
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Vin
+
VDAC
–
DAC
FULL SCALE
SUCCESSIVE
APPROXIMATION
REGISTER
SUCCESSIVE
APPROXIMATION
CONTROL LOGIC
START
STOP
1
15/16
Vin
3/4
P87C552
59/64
29/32
7/8
1/2
VDAC
0
1
2
3
4
5
6
t/tau
SU00958
Figure 20. Successive Approximation ADC
previous result), and VDAC is compared to Vin again. If the input
voltage is greater than VDAC, then the bit being tested remains set;
otherwise the bit being tested is cleared. This process is repeated
until all ten bits have been tested, at which stage the result of the
conversion is held in the successive approximation register.
Figure 21 shows a conversion flow chart. The bit pointer identifies
the bit under test. The conversion takes four machine cycles per bit.
The low-to-high transition of STADC is recognized at the end of a
machine cycle, and the conversion commences at the beginning of
the next cycle. When a conversion is initiated by software, the
conversion starts at the beginning of the machine cycle which
follows the instruction that sets ADCS. ADCS is actually
implemented with two flip-flops: a command flip-flop which is
affected by set operations, and a status flag which is accessed
during read operations.
The end of the 10-bit conversion is flagged by control bit ADCON.4
(ADCI). The upper 8 bits of the result are held in special function
register ADCH, and the two remaining bits are held in ADCON.7
(ADC.1) and ADCON.6 (ADC.0). The user may ignore the two least
significant bits in ADCON and use the ADC as an 8-bit converter (8
upper bits in ADCH). In any event, the total actual conversion time is
50 machine cycles for the 8XC552. ADCI will be set and the ADCS
status flag will be reset 50 (or 24) cycles after the command flip-flop
(ADCS) is set.
The next two machine cycles are used to initiate the converter. At
the end of the first cycle, the ADCS status flag is set and a value of
“1” will be returned if the ADCS flag is read while the conversion is in
progress. Sampling of the analog input commences at the end of the
second cycle.
During the next eight machine cycles, the voltage at the previously
selected pin of port 5 is sampled, and this input voltage should be
stable in order to obtain a useful sample. In any event, the input
voltage slew rate must be less than 10V/ms in order to prevent an
undefined result.
Control bits ADCON.0, ADCON.1, and ADCON.2 are used to control
an analog multiplexer which selects one of eight analog channels
(see Figure 22). An ADC conversion in progress is unaffected by an
external or software ADC start. The result of a completed
conversion remains unaffected provided ADCI = logic 1; a new ADC
conversion already in progress is aborted when the idle or
power-down mode is entered. The result of a completed conversion
(ADCI = logic 1) remains unaffected when entering the idle mode.
The successive approximation control logic first sets the most
significant bit and clears all other bits in the successive
approximation register (10 0000 0000B). The output of the DAC
(50% full scale) is compared to the input voltage Vin. If the input
voltage is greater than VDAC, then the bit remains set; otherwise it
is cleared.
The successive approximation control logic now sets the next most
significant bit (11 0000 0000B or 01 0000 0000B, depending on the
1999 Mar 30
23
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
Start of Conversion
SOC
RESET SAR
[BIT POINTER] = MSB
[BIT]N = 1
CONVERSION TIME
1
TEST
COMPLETE
0
[BIT]N = 0
[BIT POINTER] + 1
TEST BIT
POINTER
END
END
EOC END OF CONVERSION
SU00959
Figure 21. A/D Conversion Flowchart
1999 Mar 30
24
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
7
ADCON (C5H)
ADC.1
6
5
4
ADC.0 ADEX
3
2
1
ADCI ADCS AADR2 AADR1
P87C552
0
AADR0
(MSB)
Bit
Symbol
ADCON.7
ADCON.6
ADCON.5
ADC.1
ADC.0
ADEX
ADCON.4
ADCI
ADCON.3
ADCS
Reset Value = xx00 0000B
(LSB)
Function
Bit 1 of ADC result
Bit 0 of ADC result
Enable external start of conversion by STADC
0 = Conversion can be started by software only (by setting ADCS)
1 = Conversion can be started by software or externally (by a rising edge on STADC)
ADC interrupt flag: this flag is set when an A/D conversion result is ready to be read. An interrupt is
invoked if it is enabled. The flag may be cleared by the interrupt service routine. While this flag is set,
the ADC cannot start a new conversion. ADCI cannot be set by software.
ADC start and status: setting this bit starts an A/D conversion. It may be set by software or by the
external signal STADC. The ADC logic ensures that this signal is HIGH while the ADC is busy. On
completion of the conversion, ADCS is reset immediately after the interrupt flag has been set. ADCS
cannot be reset by software. A new conversion may not be started while either ADCS or ADCI is high.
ADCI
0
0
1
1
ADCS
0
1
0
1
ADC Status
ADC not busy; a conversion can be started
ADC busy; start of a new conversion is blocked
Conversion completed; start of a new conversion requires ADCI=0
Conversion completed; start of a new conversion requires ADCI=0
If ADCI is cleared by software while ADCS is set at the same time, a new A/D conversion with the
same channel number may be started.
But it is recommended to reset ADCI before ADCS is set.
ADCON.2
ADCON.1
ADCON.0
AADR2
AADR1
AADR0
Analogue input select: this binary coded address selects one of the
eight analogue port bits of P5 to be input to the converter. It can only
be changed when ADCI and ADCS are both LOW.
AADR2
AADR1
AADR0
Selected Analog Channel
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
ADC0 (P5.0)
ADC1 (P5.1)
ADC2 (P5.2)
ADC3 (P5.3)
ADC4 (P5.4)
ADC5 (P5.5)
ADC6 (P5.6)
ADC7 (P5.7)
SU00960
Figure 22. ADC Control Register (ADCON)
1999 Mar 30
25
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Power Reduction Modes
The 8XC552 has two reduced power modes of operation: the idle
mode and the power-down mode. These modes are entered by
setting bits in the PCON special function register. When the 8XC552
enters the idle mode, the following functions are disabled:
10-Bit ADC Resolution and Analog Supply: Figure 23 shows how
the ADC is realized. The ADC has its own supply pins (AVDD and
AVSS) and two pins (Vref+ and Vref–) connected to each end of the
DAC’s resistance-ladder. The ladder has 1023 equally spaced taps,
separated by a resistance of “R”. The first tap is located 0.5 x R
above Vref–, and the last tap is located 1.5 x R below Vref+. This
gives a total ladder resistance of 1024 x R. This structure ensures
that the DAC is monotonic and results in a symmetrical quantization
error as shown in Figure 25.
CPU
Timer T2
PWM0, PWM1
ADC
For input voltages between Vref– and (Vref–) + 1/2 LSB, the 10-bit
result of an A/D conversion will be 00 0000 0000B = 000H. For input
voltages between (Vref+) – 3/2 LSB and Vref+, the result of a
conversion will be 11 1111 1111B = 3FFH. AVref+ and AVref– may
be between AVDD + 0.2V and AVSS – 0.2V. AVref+ should be
positive with respect to AVref–, and the input voltage (Vin) should be
between AVref+ and AVref–. If the analog input voltage range is from
2V to 4V, then 10-bit resolution can be obtained over this range if
AVref+ = 4V and AVref– = 2V.
(halted)
(halted and reset)
(reset; outputs are high)
(may be enabled for operation in Idle mode
by setting bit AIDC (AUXR1.6) ).
In idle mode, the following functions remain active:
Timer 0
Timer 1
Timer T3
SIO0 SIO1
External interrupts
When the 8XC552 enters the power-down mode, the oscillator is
stopped. The power-down mode is entered by setting the PD bit in
the PCON register. The PD bit can only be set if the EW input is tied
HIGH.
The result can always be calculated from the following formula:
Result 1024 P87C552
V IN AV ref
AV ref AV ref
AVref+
R/2
1023
MSB
R
R
1022
START
R
1021
DECODER
TOTAL RESISTANCE
= 1023R + 2 x R/
= 1024R
SUCCESSIVE
APPROXIMATION
REGISTER
SUCCESSIVE
APPROXIMATION
CONTROL LOGIC
3
2
READY
R
1
R
LSB
0
R/2
AVref–
Vref
–
COMPARATOR
Vin
Value 0000 0000 00
Value 1111 1111 11
+
is output for voltages Vref– to (Vref– + 1/2 LSB)
is output for voltages (Vref+ – 3/2 LSB) to Vref+
Figure 23. ADC Realization
1999 Mar 30
26
SU00961
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
SmN+1
RmN+1
SmN
RmN
P87C552
IN+1
IN
TO COMPARATOR
+
MULTIPLEXER
RS
CC
CS
VANALOG
INPUT
Rm = 0.5 - 3 kΩ
CS + CC = 15pF maximum
RS = Recommended < 9.6 kΩ for 1 LSB @ 12MHz
NOTE:
Because the analog to digital converter has a sampled-data comparator, the input looks capacitive to a source. When a conversion
is initiated, switch Sm closes for 8tCY (8µs @ 12MHz crystal frequency) during which time capacitance CS + CC is charged. It should
be noted that the sampling causes the analog input to present a varying load to an analog source.
SU00962
Figure 24. A/D Input: Equivalent Circuit
CODE
OUT
101
100
011
010
001
000
0
q
2q
3q
4q
5q
Vin
QUANTIZATION ERROR
q = LSB = 5 mV
Vin – Vdigital
+ q/2
– q/2
Vin
SYMMETRICAL QUANTIZATION ERROR
SU00963
Figure 25. Effective Conversion Characteristic
1999 Mar 30
27
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
interrupt enable special function registers IEN0 and IEN1. All
interrupt sources can also be globally enabled or disabled by setting
or clearing bit EA in IEN0. The interrupt enable registers are
described in Figures 26 and 27.
Interrupts
The 8XC552 has fifteen interrupt sources, each of which can be
assigned one of four priority levels. The five interrupt sources
common to the 80C51 are the external interrupts (INT0 and INT1),
the timer 0 and timer 1 interrupts (IT0 and IT1), and the serial I/O
interrupt (RI or TI). In the 8XC552, the standard serial interrupt is
called SIO0.
There are 3 SFRs associated with each of the four-level interrupts.
They are the IENx, IPx, and IPxH. (See Figures 28, 29, and 30.) The
IPxH (Interrupt Priority High) register makes the four-level interrupt
structure possible.
The eight Timer T2 interrupts are generated by flags CTI0-CT13,
CMI0-CMI2, and by the logical OR of flags T2OV and T2BO. Flags
CTI0 to CT13 are set by input signals CT0I to CT3i. Flags CMI0 to
CMI2 are set when a match occurs between Timer T2 and the
compare registers CM0, CM1, and CM2. When an 8-bit or 16-bit
overflow occurs, flags T2BO and T2OV are set, respectively. These
nine flags are not cleared by hardware and must be reset by
software to avoid recurring interrupts.
The function of the IPxH SFR is simple and when combined with the
IPx SFR determines the priority of each interrupt. The priority of
each interrupt is determined as shown in the following table:
PRIORITY BITS
INTERRUPT PRIORITY LEVEL
IPxH.x
IPx.x
The ADC interrupt is generated by the ADCI flag in the ADC control
register (ADCON). This flag is set when an ADC conversion result is
ready to be read. ADCI is not cleared by hardware and must be
reset by software to avoid recurring interrupts.
0
0
Level 0 (lowest priority)
0
1
Level 1
1
0
Level 2
The SIO1 (I2C) interrupt is generated by the SI flag in the SIO1
control register (S1CON). This flag is set when S1STA is loaded
with a valid status code.
1
1
Level 3 (highest priority)
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
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 ADCI flag may be reset by software. It cannot be set by
software. All other flags that generate interrupts may be set or
cleared by software, and the effect is the same as setting or
resetting the flags by hardware. Thus, interrupts may be generated
by software and pending interrupts can be canceled by software.
Interrupt Enable Registers: Each interrupt source can be
individually enabled or disabled by setting or clearing a bit in the
IEN0 (A8H)
7
6
5
4
3
2
1
0
EA
EAD
ES1
ES0
ET1
EX1
ET0
EX0
(MSB)
(LSB)
BIT
SYMBOL
FUNCTION
IEN0.7
EA
IEN0.6
IEN0.5
IEN0.4
IEN0.3
IEN0.2
IEN0.1
IEN0.0
EAD
ES1
ES0
ET1
EX1
ET0
EX0
Global enable/disable control
0 = No interrupt is enabled
1 = Any individually enabled interrupt will be accepted
Eanble ADC interrupt
Enable SIO1 (I2C) interrupt
Enable SIO0 (UART) interrupt
Enable Timer 1 interrupt
Enable External interrupt 1
Enable Timer 0 interrupt
Enable External interrupt 0
SU00762
Figure 26. Interrupt Enable Register (IEN0)
1999 Mar 30
28
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
IEN1 (E8H)
P87C552
7
6
5
4
3
2
1
0
ET2
ECM2
ECM1
ECM0
ECT3
ECT2
ECT1
ECT0
(MSB)
(LSB)
BIT
SYMBOL
FUNCTION
IEN1.7
IEN1.6
IEN1.5
IEN1.4
IEN1.3
IEN1.2
IEN1.1
IEN1.0
ET2
ECM2
ECM1
ECM0
ECT3
ECT2
ECT1
ECT0
Enable Timer T2 overflow interrupt(s)
Enable T2 Comparator 2 interrupt
Enable T2 Comparator 1 interrupt
Enable T2 Comparator 0 interrupt
Enable T2 Capture register 3 interrupt
Enable T2 Capture register 2 interrupt
Enable T2 Capture register 1 interrupt
Enable T2 Capture register 0 interrupt
SU00755
In all cases, if the enable bit is 0, then the interrupt is disabled, and if the enable bit is 1, then the interrupt is enabled.
Figure 27. Interrupt Enable Register (IEN1)
IP0 (B8H)
7
6
5
4
3
2
1
0
–
PAD
PS1
PS0
PT1
PX1
PT0
PX0
(MSB)
(LSB)
BIT
SYMBOL
FUNCTION
IP0.7
IP0.6
IP0.5
IP0.4
IP0.3
IP0.2
IP0.1
IP0.0
–
PAD
PS1
PS0
PT1
PX1
PT0
PX0
Unused
ADC interrupt priority level
SIO1 (I2C) interrupt priority level
SIO0 (UART) interrupt priority level
Timer 1 interrupt priority level
External interrupt 1 priority level
Timer 0 interrupt priority level
External interrupt 0 priority level
SU00763
Figure 28. Interrupt Priority Register (IP0)
IP0H (B7H)
7
6
5
4
3
2
1
0
–
PADH
PS1H
PS0H
PT1H
PX1H
PT0H
PX0H
(MSB)
(LSB)
BIT
SYMBOL
FUNCTION
IP0H.7
IP0H.6
IP0H.5
IP0H.4
IP0H.3
IP0H.2
IP0H.1
IP0H.0
–
PADH
PS1H
PS0H
PT1H
PX1H
PT0H
PX0H
Unused
ADC interrupt priority level high
SIO1 (I2C) interrupt priority level high
SIO0 (UART) interrupt priority level high
Timer 1 interrupt priority level high
External interrupt 1 priority level high
Timer 0 interrupt priority level high
External interrupt 0 priority level high
SU00983
Figure 29. Interrupt Priority Register High (IP0H)
1999 Mar 30
29
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
IP1 (F8H)
P87C552
7
6
5
4
3
2
1
0
PT2
PCM2
PCM1
PCM0
PCT3
PCT2
PCT1
PCT0
(MSB)
(LSB)
BIT
SYMBOL
FUNCTION
IP1.7
IP1.6
IP1.5
IP1.4
IP1.3
IP1.2
IP1.1
IP1.0
PT2
PCM2
PCM1
PCM0
PCT3
PCT2
PCT1
PCT0
T2 overflow interrupt(s) priority level
T2 comparator 2 interrupt priority level
T2 comparator 1 interrupt priority level
T2 comparator 0 interrupt priority level
T2 capture register 3 interrupt priority level
T2 capture register 2 interrupt priority level
T2 capture register 1 interrupt priority level
T2 capture register 0 interrupt priority level
SU00764
Figure 30. Interrupt Priority Register (IP1)
7
IP1H (F7H)
6
PT2H
5
4
3
PCM2H PCM1H PCM0H PCT3H
2
1
0
PCT2H
PCT1H
PCT0H
(MSB)
(LSB)
BIT
SYMBOL
FUNCTION
IP1H.7
IP1H.6
IP1H.5
IP1H.4
IP1H.3
IP1H.2
IP1H.1
IP1H.0
PT2H
PCM2H
PCM1H
PCM0H
PCT3H
PCT2H
PCT1H
PCT0H
T2 overflow interrupt(s) priority level high
T2 comparator 2 interrupt priority level high
T2 comparator 1 interrupt priority level high
T2 comparator 0 interrupt priority level high
T2 capture register 3 interrupt priority level high
T2 capture register 2 interrupt priority level high
T2 capture register 1 interrupt priority level high
T2 capture register 0 interrupt priority level high
SU00984
Figure 31. Interrupt Priority Register High (IP1H)
Table 3.
Interrupt Priority Structure
SOURCE
External interrupt 0
SIO1 (I2C)
ADC completion
Timer 0 overflow
T2 capture 0
T2 compare 0
External interrupt 1
T2 capture 1
T2 compare 1
Timer 1 overflow
T2 capture 2
T2 compare 2
SIO0 (UART)
T2 capture 3
Timer T2 overflow
1999 Mar 30
NAME
X0
S1
ADC
T0
CT0
CM0
X1
CT1
CM1
T1
CT2
CM2
S0
CT3
T2
Table 4.
Interrupt Vector Addresses
SOURCE
PRIORITY WITHIN LEVEL
External interrupt 0
Timer 0 overflow
External interrupt 1
Timer 1 overflow
SIO0 (UART)
SIO1 (I2C)
T2 capture 0
T2 capture 1
T2 capture 2
T2 capture 3
ADC completion
T2 compare 0
T2 compare 1
T2 compare 2
T2 overflow
(highest)
↑
↓
(lowest)
30
NAME
VECTOR ADDRESS
X0
T0
X1
T1
S0
S1
CT0
CT1
CT2
CT3
ADC
CM0
CM1
CM2
T2
0003H
000BH
0013H
001BH
0023H
002BH
0033H
003BH
0043H
004BH
0053H
005BH
0063H
006BH
0073H
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
SIO1, I2C Serial I/O: 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
Modes of Operation: The on-chip SIO1 logic may operate in the
following four modes:
The output latches of P1.6 and P1.7 must be set to logic 1 in order
to enable SIO1.
2. Master Receiver Mode:
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 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 8XC552 on-chip I2C 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 SIO1 logic
handles bytes transfer autonomously. It also keeps track of serial
transfers, and a status register (S1STA) reflects the status of SIO1
and the I2C bus.
The CPU interfaces to the I2C logic via the following four special
function registers: S1CON (SIO1 control register), S1STA (SIO1
status register), S1DAT (SIO1 data register), and S1ADR (SIO1
slave address register). The SIO1 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).
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.
A typical I2C bus configuration is shown in Figure 32, and Figure 33
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.
4. Slave Transmitter Mode:
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.
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.
In a given application, SIO1 may operate as a master and as a
slave. In the slave mode, the SIO1 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, SIO1
switches to the slave mode immediately and can detect its own
slave address in the same serial transfer.
The master device generates all of the serial clock pulses and the
START and STOP conditions. A transfer is ended with a STOP
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.
1999 Mar 30
31
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
VDD
RP
RP
SDA
I2C bus
SCL
P1.7/SDA
P1.6/SCL
OTHER DEVICE WITH
I2C INTERFACE
8XC554
OTHER DEVICE WITH
I2C INTERFACE
SU00964
Figure 32. 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 33. Data Transfer on the
I2 C
Bus
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.
SIO1 Implementation and Operation: Figure 34 shows how the
on-chip I2C bus interface is implemented, and the following text
describes the individual blocks.
INPUT FILTERS AND OUTPUT STAGES
The input filters have I2C compatible input levels. If the input voltage
is less than 1.5V, the input logic level is interpreted as 0; if the input
voltage is greater than 3.0V, 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 < 0.4V. 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 SIO1 will respond when
programmed as a slave transmitter or receiver. The LSB (GC) is
used to enable general call address (00H) recognition.
1999 Mar 30
3–8
32
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
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 34.
1999 Mar 30
I 2C
Bus Serial Interface Block Diagram
33
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
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 36 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 SIO1 immediately changes from
master transmitter to slave receiver. SIO1 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. SIO1 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 SIO1 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, SIO1 generates no further clock pulses.
Figure 35 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 35. 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 36. Serial Clock Synchronization
1999 Mar 30
34
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
read from and write to this 8-bit, directly addressable SFR while it is
not in the process of shifting a byte. This occurs when SIO1 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 SIO1 is in the master transmitter or master receiver
mode. It is switched off when SIO1 is in a slave 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.
S1DAT (DAH)
5
4
3
2
1
0
X
X
X
X
X
X
GC
3
2
1
0
SD3
SD2
SD1
SD0
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 38). 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 Control Register, S1CON: The CPU can read from and write
to this 8-bit, directly addressable SFR. Two bits are affected by the
SIO1 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 SIO1 ENABLE BIT
ENS1 = “0”: When ENS1 is “0”, the SDA and SCL outputs are in a
high impedance state. SDA and SCL input signals are ignored, SIO1
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”, SIO1 is enabled. The P1.6 and P1.7
port latches must be set to logic 1.
ENS1 should not be used to temporarily release SIO1 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
1999 Mar 30
4
SD4
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 SIO1 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 Address Register, S1ADR: The CPU can read from and write
to this 8-bit, directly addressable SFR. S1ADR is not affected by the
SIO1 hardware. The contents of this register are irrelevant when
SIO1 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.
6
5
SD5
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 37 shows how data in S1DAT is
serially transferred to and from the SDA line.
The Four SIO1 Special Function Registers: The microcontroller
interfaces to SIO1 via four special function registers. These four
SFRs (S1ADR, S1DAT, S1CON, and S1STA) are described
individually in the following sections.
X
6
SD6
shift direction
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 SIO1 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).
7
7
SD7
SD7 - SD0:
CONTROL REGISTER, S1CON
This 7-bit special function register is used by the microcontroller to
control the following SIO1 functions: start and restart of a serial
transfer, termination of a serial transfer, bit rate, address recognition,
and acknowledgment.
S1ADR (DBH)
P87C552
35
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
INTERNAL BUS
SDA
8
BSD7
S1DAT
ACK
SCL
SHIFT PULSES
SU00969
Figure 37. 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 38. Shift-in and Shift-out Timing
STA = “0”: When the STA bit is reset, no START condition or
repeated START condition will be generated.
In the following text, it is assumed that ENS1 = “1”.
STA, THE START FLAG
STA = “1”: When the STA bit is set to enter a master mode, the SIO1
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 SIO1 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 SIO1 is in a master mode,
a STOP condition is transmitted to the I2C bus. When the STOP
condition is detected on the bus, the SIO1 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 SIO1 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 SIO1 is already in a master mode and one or
more bytes are transmitted or received, SIO1 transmits a repeated
START condition. STA may be set at any time. STA may also be set
when SIO1 is an addressed slave.
1999 Mar 30
36
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
When SIO1 is in the addressed slave transmitter mode, state C8H
will be entered after the last serial is transmitted (see Figure 42).
When SI is cleared, SIO1 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.
If the STA and STO bits are both set, the a STOP condition is
transmitted to the I2C bus if SIO1 is in a master mode (in a slave
mode, SIO1 generates an internal STOP condition which is not
transmitted). SIO1 then transmits a START condition.
STO = “0”: When the STO bit is reset, no STOP condition will be
generated.
When SIO1 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, SIO1 can be temporarily released from the I2C bus while the
bus status is monitored. While SIO1 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.
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 SIO1 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.
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.
CR0, CR1, AND CR2, THE CLOCK RATE BITS
These three bits determine the serial clock frequency when SIO1 is
in a master mode. The various serial rates are shown in Table 5.
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.
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
16MHz, 12MHz, or a 6MHz 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 SIO1 is in a master mode.
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 SIO1 is in the master
receiver mode
– A data byte has been received while SIO1 is in the addressed
slave receiver mode
The frequencies shown in Table 5 are unimportant when SIO1 is in a
slave mode. In the slave modes, SIO1 will automatically synchronize
with any clock frequency up to 100kHz.
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 SIO1 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.
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 SIO1 is in the master receiver
mode
– A data byte has been received while SIO1 is in the addressed
slave receiver mode
Table 5.
P87C552
Serial Clock Rates
BIT FREQUENCY (kHz) AT fOSC
CR2
CR1
CR0
6MHz
12MHz
16MHz
fOSC DIVIDED BY
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
23
27
31
37
6.25
50
100
0.24 < 62.5
0 < 255
47
54
63
75
12.5
100
200
0.49 < 62.5
0 < 254
62.5
71
83.3
100
17
1331
2671
0.65 < 55.6
0 < 253
256
224
192
160
960
120
60
96 × (256 – (reload value Timer 1))
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.
1999 Mar 30
37
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
may switch to the master receiver mode by loading S1DAT with
SLA+R).
More Information on SIO1 Operating Modes: The four operating
modes are:
– Master Transmitter
– Master Receiver
– Slave Receiver
– Slave Transmitter
Master Receiver Mode: In the master receiver mode, a number of
data bytes are received from a slave transmitter (see Figure 40).
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
39–42. 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 7. ENS1, CR1, and CR0 are not
affected by the serial transfer and are not referred to in Table 7. After
a repeated start condition (state 10H), SIO1 may switch to the
master transmitter mode by loading S1DAT with SLA+W.
In Figures 39-42, 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 41).
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 6-10.
S1ADR (DBH)
7
6
5
X
X
X
4
3
2
1
0
X
X
X
X
GC
own slave address
Master Transmitter Mode: In the master transmitter mode, a
number of data bytes are transmitted to a slave receiver (see
Figure 39). Before the master transmitter mode can be entered,
S1CON must be initialized as follows:
S1CON (D8H)
P87C552
The upper 7 bits are the address to which SIO1 will respond when
addressed by a master. If the LSB (GC) is set, SIO1 will respond to
the general call address (00H); otherwise it ignores the general call
address.
7
6
5
4
3
2
1
0
CR2
ENS1
STA
STO
SI
AA
CR1
CR0
bit
rate
1
0
0
0
X
S1CON (D8H)
bit rate
CR0, CR1, and CR2 define the serial bit rate. ENS1 must be set to
logic 1 to enable SIO1. If the AA bit is reset, SIO1 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.
7
6
5
4
3
2
1
0
CR2
ENS1
STA
STO
SI
AA
CR1
CR0
X
1
0
0
0
1
X
X
CR0, CR1, and CR2 do not affect SIO1 in the slave mode. ENS1
must be set to logic 1 to enable SIO1. The AA bit must be set to
enable SIO1 to acknowledge its own slave address or the general
call address. STA, STO, and SI must be reset.
The master transmitter mode may now be entered by setting the
STA bit using the SETB instruction. The SIO1 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.
When S1ADR and S1CON have been initialized, SIO1 waits until it
is addressed by its own slave address followed by the data direction
bit which must be “0” (W) for SIO1 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 8. The slave receiver
mode may also be entered if arbitration is lost while SIO1 is in the
master mode (see status 68H and 78H).
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 6. After a repeated start condition (state 10H). SIO1
If the AA bit is reset during a transfer, SIO1 will return a not
acknowledge (logic 1) to SDA after the next received data byte.
While AA is reset, SIO1 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 SIO1
from the I2C bus.
1999 Mar 30
38
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
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 6.
SU00971
Figure 39. Format and States in the Master Transmitter Mode
1999 Mar 30
39
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
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 7.
SU00972
Figure 40. Format and States in the Master Receiver Mode
1999 Mar 30
40
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
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
A
DATA
SLA
80H
60H
LAST DATA BYTE RECEIVED IS
NOT ACKNOWLEDGED
P87C552
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 8.
SU00973
Figure 41. Format and States in the Slave Receiver Mode
1999 Mar 30
41
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
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
ÇÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇ
ÇÇÇÇ
ÇÇÇ
ÇÇÇ
A
n
A
A
P or S
C0H
ARBITRATION LOAST 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
P87C552
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 9.
SU00974
Figure 42. Format and States of the Slave Transmitter Mode
1999 Mar 30
42
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Table 6.
STATUS
CODE
(S1STA)
P87C552
Master Transmitter Mode
STATUS OF THE
I2C BUS AND
SIO1 HARDWARE
APPLICATION SOFTWARE RESPONSE
TO S1CON
TO/FROM S1DAT
NEXT ACTION TAKEN BY SIO1 HARDWARE
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;
SIO1 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
1999 Mar 30
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
b
Data
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
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Table 7.
STATUS
CODE
(S1STA)
P87C552
Master Receiver Mode
STATUS OF THE I2C
BUS AND
SIO1 HARDWARE
APPLICATION SOFTWARE RESPONSE
TO S1CON
TO/FROM S1DAT
NEXT ACTION TAKEN BY SIO1 HARDWARE
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;
SIO1 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;
SIO1 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
1999 Mar 30
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
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Table 8.
Slave Receiver Mode
STATUS
CODE
(S1STA)
60H
68H
70H
78H
80H
88H
90H
98H
P87C552
STATUS OF THE
I2C BUS AND
SIO1 HARDWARE
APPLICATION SOFTWARE RESPONSE
TO S1CON
TO/FROM S1DAT
NEXT ACTION TAKEN BY SIO1 HARDWARE
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.
1999 Mar 30
45
Data byte will be received and NOT ACK will be
returned
Data byte will be received and ACK will be returned
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Table 8.
P87C552
Slave Receiver Mode (Continued)
STATUS
CODE
(S1STA)
STATUS OF THE
I2C BUS AND
SIO1 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 9.
APPLICATION SOFTWARE RESPONSE
TO S1CON
TO/FROM S1DAT
NEXT ACTION TAKEN BY SIO1 HARDWARE
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)
STATUS OF THE
I2C BUS AND
SIO1 HARDWARE
APPLICATION SOFTWARE RESPONSE
TO S1CON
TO/FROM S1DAT
NEXT ACTION TAKEN BY SIO1 HARDWARE
STA
STO
SI
AA
A8H
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
B0H
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
B8H
C0H
C8H
Last data byte in
S1DAT has been
i d (AA = 0);
0)
transmitted
ACK has been
received
1999 Mar 30
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
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
Table 10.
P87C552
Miscellaneous States
STATUS
CODE
(S1STA)
STATUS OF THE
I2C BUS AND
SIO1 HARDWARE
APPLICATION SOFTWARE RESPONSE
TO S1CON
TO/FROM S1DAT
STA
F8H
No relevant state
information available;
SI = 0
No S1DAT action
00H
Bus error during MST
or selected slave
modes, due to an
illegal START or
STOP condition. State
00H can also occur
when interference
causes SIO1 to enter
an undefined state.
No S1DAT action
STO
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 SIO1 is switched to the not addressed
SLV mode. STO is reset.
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 42).
Data transfer is initialized as in the slave receiver mode. When
S1ADR and S1CON have been initialized, SIO1 waits until it is
addressed by its own slave address followed by the data direction
bit which must be “1” (R) for SIO1 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 9. The slave transmitter mode
may also be entered if arbitration is lost while SIO1 is in the master
mode (see state B0H).
Some Special Cases: The SIO1 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 43). Until this occurs, arbitration is not lost by
either master since they were both transmitting the same data.
If the SIO1 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, SIO1 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, SIO1 will transmit the last byte
of the transfer and enter state C0H or C8H. SIO1 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, SIO1 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 SIO1 from the I2C bus.
DATA TRANSFER AFTER LOSS OF ARBITRATION
Arbitration may be lost in the master transmitter and master receiver
modes (see Figure 35). Loss of arbitration is indicated by the
following states in S1STA; 38H, 68H, 78H, and B0H (see Figures 39
and 40).
Miscellaneous States: There are two S1STA codes that do not
correspond to a defined SIO1 hardware state (see Table 10). 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 SIO1 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
SIO1 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 SIO1
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
SIO1 to enter the “not addressed” slave mode (a defined state) and
to clear the STO flag (no other bits in S1CON are affected). The
1999 Mar 30
SI
NEXT ACTION TAKEN BY SIO1 HARDWARE
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 SIO1 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 44).
47
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
S
SLA
08H
W
A
DATA
18H
A
S
P87C552
OTHER MST
CONTINUES
P
28H
S
SLA
08H
OTHER MASTER SENDS REPEATED
START CONDITION EARLIER
RETRY
SU00975
Figure 43. Simultaneous Repeated START Conditions from 2 Masters
TIME LIMIT
STA FLAG
STO FLAG
SDA LINE
SCL LINE
START CONDITION
SU00976
Figure 44. 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
SIO1 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.
Bus
hardware 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
45). The SIO1 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 SIO1 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 SIO1 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, SIO1 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 10.
If a forced bus access occurs or a repeated START condition is
transmitted while SDA is obstructed (pulled LOW), the SIO1
1999 Mar 30
I2 C
48
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
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 45. Recovering from a Bus Obstruction Caused by a Low Level on SDA
SIO1 INTERRUPT ROUTINE
When the SIO1 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 SIO1 Service Routines: This section
consists of a software example for:
– Initialization of SIO1 after a RESET
– Entering the SIO1 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, SIO1 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 46. 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 SIO1 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 SIO1 interrupt routine and handles one of the 26 states. It ends
with a RETI instruction which causes a return to the main program.
The SIO1 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.
1999 Mar 30
PUSH PSW
PUSH S1STA
49
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
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 46. SIO1 Data Memory Map
1999 Mar 30
50
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
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 SIO1 operates in the master transmitter
or master 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 6, Table 7,
Figure 39, and Figure 40. 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 SIO1 enters the
not selected slave receiver mode. If a slave device returns a not
acknowledge, a STOP condition is generated.
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, SIO1 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 8, Table 9, Figure 41,
and Figure 42). If arbitration was lost while in the master mode, the
master mode is restarted after the current transfer. If a bus error
occurs, the I2C bus is released and SIO1 enters the not selected
slave 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 SIO1 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 SIO1 enters
the not addressed slave receiver mode.
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, SIO1 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.
This example does not include any time-out routines. In the slave
modes, time-out routines are not very useful since, in these modes,
SIO1 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.
1999 Mar 30
51
P87C552
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
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 SIO1 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
1999 Mar 30
! 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
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
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
1999 Mar 30
S1CON,#ENS1_NOTSTA_STO_NOTSI_AA_CR0 ! clr SI
! set STO,AA
psw
53
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
!********************************************************************************************************
!********************************************************************************************************
! 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
1999 Mar 30
mov psw,#SELRB3
mov S1DAT,@r1
ajmp CON
54
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! 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
1999 Mar 30
mov S1CON,#ENS1_STA_NOTSTO_NOTSI_AA_CR0
mov NUMBYTMST,BACKUP
ajmp RETmt
55
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
!********************************************************************************************************
!********************************************************************************************************
! 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
1999 Mar 30
mov psw,#SELRB3
mov @R0,S1DAT
sjmp STOP
56
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
!********************************************************************************************************
!********************************************************************************************************
! 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
1999 Mar 30
57
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! 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
1999 Mar 30
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
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! 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
1999 Mar 30
mov S1DAT,STD
! load DATA in S1DAT
mov S1CON,#ENS1_STA_NOTSTO_NOTSI_AA_CR0
ajmp INITBASE2
59
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
01B8
01BB
01BD
75D018
87DA
01F8
P87C552
!– – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – – –
! 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
!********************************************************************************************************
!********************************************************************************************************
1999 Mar 30
60
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
ABSOLUTE MAXIMUM RATINGS1, 2, 3
PARAMETER
RATING
UNIT
Storage temperature range
–65 to +150
°C
Voltage on EA/VPP to VSS
–0.5 to +13
V
Voltage on any other pin to VSS
–0.5 to +6.5
V
Input, output DC current on any single I/O pin
5.0
mA
Power dissipation (based on package heat transfer limitations, not device power
consumption)
1.0
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 maxima.
3. Parameters are valid over operating temperature range unless otherwise specified. All voltages are with respect to VSS unless otherwise
noted.
DEVICE SPECIFICATIONS
SUPPLY VOLTAGE (V)
FREQUENCY (MHz)
TYPE
TEMPERATURE RANGE (°C)
MIN
MAX
MIN
MAX
P87C552 SBxx versions
2.7
5.5
0
16
0 to +70
P87C552 SFxx versions
2.7
5.5
0
16
–40 to +85
1999 Mar 30
61
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
DC ELECTRICAL CHARACTERISTICS
VSS, AVSS = 0V
LIMITS
SYMBOL
PARAMETER
TEST CONDITIONS
IDD
Supply current operating
See notes 1 and 2
fOSC = 16MHz
16
mA
IID
Idle mode
See notes 1 and 3
fOSC = 16MHz
4
mA
IPD
Power-down current
See notes 1 and 4;
2V < VPD < VDD max
50
µA
MIN
MAX
UNIT
Inputs
VIL
Input low voltage, except EA, P1.6, P1.7
–0.5
0.2VDD–0.1
V
VIL1
Input low voltage to EA
–0.5
0.2VDD–0.3
V
P1.7/SDA5
VIL2
Input low voltage to P1.6/SCL,
VIH
Input high voltage, except XTAL1, RST
–0.5
0.3VDD
V
0.2VDD+0.9
VDD+0.5
V
VIH1
VIH2
Input high voltage, XTAL1, RST
0.7VDD
VDD+0.5
V
Input high voltage, P1.6/SCL, P1.7/SDA5
0.7VDD
6.0
V
IIL
Logical 0 input current, ports 1, 2, 3, 4, except P1.6, P1.7
ITL
Logical 1-to-0 transition current, ports 1, 2, 3, 4, except P1.6, P1.7
VIN = 0.45V
–50
µA
See note 6
–650
µA
±IIL1
Input leakage current, port 0, EA, STADC, EW
0.45V < VI < VDD
10
µA
±IIL2
Input leakage current, P1.6/SCL, P1.7/SDA
0V < VI < 6V
0V < VDD < 5.5V
10
µA
±IIL3
Input leakage current, port 5
0.45V < VI < VDD
1
µA
±IIL4
Input leakage current, ports 1, 2, 3, 4 in high impedance mode
0.45V < Vin < VDD
10
µA
Outputs
VOL
Output low voltage, ports 1, 2, 3, 4, except P1.6, P1.7
IOL = 1.6mA7
0.4
V
VOL1
Output low voltage, port 0, ALE, PSEN, PWM0, PWM1
IOL = 3.2mA7
0.4
V
3.0mA7
0.4
V
VOL2
Output low voltage, P1.6/SCL, P1.7/SDA
IOL =
VOH
Output high voltage, ports 1, 2, 3, 4, except P1.6/SCL, P1.7/SDA
VCC = 2.7V
IOH = –20µA
07
VCC – 0.7
V
VCC = 4.5
IOH = –30µA
VCC – 0.7
07
V
VOH1
Output high voltage (port 0 in external bus mode, ALE, PSEN,
PWM0, PWM1)8
VCC = 2.7V
IOH = –3.2mA
VCC – 0.7
V
VOH2
Output high voltage (RST)
–IOH = 400µA
–IOH = 120µA
2.4
0.8VDD
V
V
RRST
Internal reset pull-down resistor
CIO
Pin capacitance
40
Test freq = 1MHz,
Tamb = 25°C
225
kΩ
10
pF
5.5
V
1.2
mA
50
µA
50
µA
Analog Inputs
AVDD
Analog supply voltage9
AVDD = VDD±0.2V
AIDD
Analog supply current operating
Port 5 = 0 to AVDD
AIID
Idle mode
AIPD
Power-down mode
1999 Mar 30
2V < AVPD < AVDD max
62
2.7
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
DC ELECTRICAL CHARACTERISTICS (Continued)
TEST
SYMBOL
PARAMETER
CONDITIONS
LIMITS
MIN
MAX
UNIT
AVDD+0.2
V
AVDD+0.2
V
V
50
kΩ
15
pF
Analog Inputs (Continued)
AVIN
Analog input voltage
AVSS–0.2
AVREF
Reference voltage:
AVREF–
AVREF+
AVSS–0.2
RREF
Resistance between AVREF+ and AVREF–
CIA
Analog input capacitance
tADS
Sampling time (10 bit mode)
8tCY
µs
tADS8
Sampling time (8 bit mode)
5tCY
µs
tADC
Conversion time (including sampling time, 10 bit mode)
50tCY
µs
tADC8
Conversion time (including sampling time, 8 bit mode)
24tCY
µs
DLe
Differential non-linearity10, 11, 12
±1
LSB
ILe
Integral non-linearity10, 13 (10 bit mode)
±2
LSB
ILe8
Integral non-linearity (8 bit mode)
±1
LSB
±2
LSB
±1
LSB
error10, 14
OSe
Offset
OSe8
Offset error (8 bit mode)
10
(10 bit mode)
error10, 15
Ge
Gain
Ae
Absolute voltage error10, 16
MCTC
Channel to channel matching
Ct
Crosstalk between inputs of port 517, 18
0–100kHz
±0.4
%
±3
LSB
±1
LSB
–60
dB
NOTES FOR DC ELECTRICAL CHARACTERISTICS:
1. See Figures 57 through 60 for IDD test conditions, and Figure 56. Active mode: IDD (max) = (0.9 x FREQ. + 1.1) mA;
Idle Mode: IID (max) = (0.18 x FREQ. + 1.01) mA.
2. The operating supply current is measured with all output pins disconnected; XTAL1 driven with tr = tf = 10ns; VIL = VSS + 0.5V;
VIH = VDD – 0.5V; XTAL2 not connected; EA = RST = Port 0 = EW = VDD; STADC = VSS.
3. The idle mode supply current is measured with all output pins disconnected; XTAL1 driven with tr = tf = 10ns; VIL = VSS + 0.5V;
VIH = VDD – 0.5V; XTAL2 not connected; Port 0 = EW = VDD; EA = RST = STADC = VSS.
4. The power-down current is measured with all output pins disconnected; XTAL2 not connected; Port 0 = EW = VDD;
EA = RST = STADC = XTAL1 = VSS.
5. The input threshold voltage of P1.6 and P1.7 (SIO1) meets the I2C specification, so an input voltage below 1.5V will be recognized as a logic
0 while an input voltage above 3.0V will be recognized as a logic 1.
6. Pins of ports 1 (except P1.6, P1.7), 2, 3, and 4 source a transition current when they are being externally driven from 1 to 0. The transition
current reaches its maximum value when VIN is approximately 2V.
7. Capacitive loading on ports 0 and 2 may cause spurious noise to be superimposed on the VOLs of ALE and ports 1 and 3. The noise is due
to external bus capacitance discharging into the port 0 and port 2 pins when these pins make 1-to-0 transitions during bus operations. In the
worst cases (capacitive loading > 100pF), the noise pulse on the ALE pin may exceed 0.8V. In such cases, it may be desirable to qualify
ALE with a Schmitt Trigger, or use an address latch with a Schmitt Trigger STROBE input. IOL can exceed these conditions provided that no
single output sinks more than 5mA and no more than two outputs exceed the test conditions.
8. Capacitive loading on ports 0 and 2 may cause the VOH on ALE and PSEN to momentarily fall below the 0.9VDD specification when the
address bits are stabilizing.
9. The following condition must not be exceeded: VDD – 0.2V < AVDD < VDD + 0.2V.
10. Conditions: AVREF– = 0V; AVDD = 5.0V. Measurement by continuous conversion of AVIN = –20mV to 5.12V in steps of 0.5mV, derivating
parameters from collected conversion results of ADC. AVREF+ = 4.977V. ADC is monotonic with no missing codes.
11. The differential non-linearity (DLe) is the difference between the actual step width and the ideal step width. (See Figure 47.)
12. The ADC is monotonic; there are no missing codes.
13. The integral non-linearity (ILe) is the peak difference between the center of the steps of the actual and the ideal transfer curve after
appropriate adjustment of gain and offset error. (See Figure 47.)
14. The offset error (OSe) is the absolute difference between the straight line which fits the actual transfer curve, and a straight line which fits the
ideal transfer curve. (See Figure 47.)
15. The gain error (Ge) is the relative difference in percent between the straight line fitting the actual transfer curve (after removing offset error),
and the straight line which fits the ideal transfer curve. Gain error is constant at every point on the transfer curve. (See Figure 47.)
16. The absolute voltage error (Ae) is the maximum difference between the center of the steps of the actual transfer curve of the non-calibrated
ADC and the ideal transfer curve.
17. This should be considered when both analog and digital signals are simultaneously input to port 5.
18. This parameter is guaranteed by design and characterized, but is not production tested.
1999 Mar 30
63
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
Offset
error
OSe
Gain
error
Ge
1023
1022
1021
1020
1019
1018
(2)
7
(1)
Code
Out
6
5
(5)
4
(4)
3
(3)
2
1
1 LSB
(ideal)
0
1
2
3
4
5
6
7
1018
1019
1020
1021
1022
1023
1024
AVIN (LSBideal)
Offset
error
OSe
1 LSB =
AVREF+
– AVREF–
1024
(1) Example of an actual transfer curve.
(2) The ideal transfer curve.
(3) Differential non-linearity (DLe).
(4) Integral non-linearity (ILe).
(5) Center of a step of the actual transfer curve.
SU00212
Figure 47. ADC Conversion Characteristic
1999 Mar 30
64
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
AC ELECTRICAL CHARACTERISTICS
16MHz CLOCK
SYMBOL
FIGURE
PARAMETER
MIN
MAX
VARIABLE CLOCK
MIN
MAX
UNIT
3.5
16
MHz
frequency5
1/tCLCL
48
Oscillator
tLHLL
48
ALE pulse width
85
2tCLCL–40
ns
tAVLL
48
Address valid to ALE low
22
tCLCL–40
ns
tLLAX
48
Address hold after ALE low
32
tCLCL–30
ns
tLLIV
48
ALE low to valid instruction in
tLLPL
48
ALE low to PSEN low
32
tCLCL–30
ns
tPLPH
48
PSEN pulse width
142
3tCLCL–45
ns
tPLIV
48
PSEN low to valid instruction in
tPXIX
48
Input instruction hold after PSEN
tPXIZ
48
Input instruction float after PSEN
37
tCLCL–25
ns
tAVIV5
48
Address to valid instruction in
207
5tCLCL–105
ns
tPLAZ
48
PSEN low to address float
10
10
ns
Speed version
:S
150
4tCLCL–100
82
0
3tCLCL–105
0
ns
ns
ns
Data Memory
tRLRH
49, 50
RD pulse width
275
6tCLCL–100
ns
tWLWH
49, 50
WR pulse width
275
tRLDV
49, 50
RD low to valid data in
tRHDX
49, 50
Data hold after RD
tRHDZ
49, 50
Data float after RD
65
2tCLCL–60
ns
tLLDV
49, 50
ALE low to valid data in
350
8tCLCL–150
ns
tAVDV
49, 50
Address to valid data in
9tCLCL–165
ns
tLLWL
49, 50
ALE low to RD or WR low
137
3tCLCL+50
ns
tAVWL
49, 50
Address valid to WR low or RD low
122
4tCLCL–130
ns
tQVWX
49, 50
Data valid to WR transition
13
tCLCL–50
ns
tWHQX
49, 50
Data hold after WR
13
tCLCL–50
ns
tQVWH
50
Data valid to WR high
287
7tCLCL–150
tRLAZ
49, 50
RD low to address float
tWHLH
49, 50
RD or WR high to ALE high
23
6tCLCL–100
147
0
ns
5tCLCL–165
0
397
239
3tCLCL–50
0
103
tCLCL–40
ns
ns
ns
0
ns
tCLCL+40
ns
External Clock
tCHCX
51
High time
20
20
tCLCL–tCLCX
ns
tCLCX
51
Low time
20
20
tCLCL–tCHCX
ns
tCLCH
51
Rise time
20
20
ns
tCHCL
51
Fall time
20
20
ns
tXLXL
52
Serial port clock cycle time
750
12tCLCL
ns
tQVXH
52
Output data setup to clock rising edge
492
10tCLCL–133
ns
tXHQX
52
Output data hold after clock rising edge
8
2tCLCL–117
ns
tXHDX
52
Input data hold after clock rising edge
0
0
ns
Shift Register
tXHDV
52
Clock rising edge to input data valid
492
10tCLCL–133
ns
NOTES:
1. Parameters are valid over operating temperature range unless otherwise specified.
2. Load capacitance for port 0, ALE, and PSEN = 100pF, load capacitance for all other outputs = 80pF.
3. Interfacing the microcontroller to devices with float times up to 45ns is permitted. This limited bus contention will not cause damage to Port 0
drivers.
4. See application note AN457 for external memory interface.
5. Parts are guaranteed to operate down to 0Hz.
1999 Mar 30
65
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
AC ELECTRICAL CHARACTERISTICS (Continued)
SYMBOL
PARAMETER
INPUT
OUTPUT
I2C Interface (Refer to Figure 55)5
tHD;STA
START condition hold time
≥ 14 tCLCL
> 4.0µs 1
tLOW
SCL low time
≥ 16 tCLCL
> 4.7µs 1
tHIGH
SCL high time
≥ 14 tCLCL
> 4.0µs 1
tRC
SCL rise time
≤ 1µs
–2
tFC
SCL fall time
≤ 0.3µs
< 0.3µs 3
tSU;DAT1
Data set-up time
≥ 250ns
> 20 tCLCL – tRD
tSU;DAT2
SDA set-up time (before rep. START cond.)
≥ 250ns
> 1µs 1
tSU;DAT3
SDA set-up time (before STOP cond.)
≥ 250ns
> 8 tCLCL
tHD;DAT
Data hold time
≥ 0ns
> 8 tCLCL – tFC
tSU;STA
Repeated START set-up time
≥ 14 tCLCL
> 4.7µs 1
tSU;STO
STOP condition set-up time
≥ 14 tCLCL
> 4.0µs 1
tBUF
Bus free time
≥ 14 tCLCL
> 4.7µs 1
tRD
SDA rise time
≤ 1µs
–2
tFD
SDA fall time
≤ 0.3µs
< 0.3µs 3
NOTES:
1. At 100 kbit/s. At other bit rates this value is inversely proportional to the bit-rate of 100 kbit/s.
2. Determined by the external bus-line capacitance and the external bus-line pull-resistor, this must be < 1µs.
3. Spikes on the SDA and SCL lines with a duration of less than 3 tCLCL will be filtered out. Maximum capacitance on bus-lines SDA and
SCL = 400pF.
4. tCLCL = 1/fOSC = one oscillator clock period at pin XTAL1. For 62ns (42s) < tCLCL < 285ns (16MHz > fOSC > 3.5MHz) the SI01 interface
meets the I2C-bus specification for bit-rates up to 100 kbit/s.
5. These values are guaranteed but not 100% production tested.
1999 Mar 30
66
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
EXPLANATION OF THE AC SYMBOLS
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
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.
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 48. 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 DPH
A0–A15 FROM PCH
SU00007
Figure 49. External Data Memory Read Cycle
1999 Mar 30
67
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
ALE
tWHLH
PSEN
tWLWH
tLLWL
WR
tLLAX
tAVLL
tWHQX
tQVWX
tDW
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 DPH
A8–A15 FROM PCH
SU00213
Figure 50. External Data Memory Write Cycle
VCC–0.5
0.7VCC
0.2VCC–0.1
0.45V
tCHCL
tCHCX
tCLCH
tCLCX
tCLCL
SU00009
Figure 51. External Clock Drive XTAL1
INSTRUCTION
0
1
2
3
4
5
6
7
8
ALE
tXLXL
CLOCK
tXHQX
tQVXH
OUTPUT DATA
0
1
WRITE TO SBUF
2
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 52. Shift Register Mode Timing
1999 Mar 30
68
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
2.4V
2.0V
2.0V
Test Points
0.8V
0.8V
0.45V
NOTE:
AC inputs during testing are driven at 2.4V for a logic ‘1’ and 0.45V for a logic ‘0’.
Timing measurements are made at 2.0V for a logic ‘1’ and 0.8V for a logic ‘0’.
SU00215
Figure 53. AC Testing Input/Output
Float
2.4V
2.4V
0.45V
2.0V
2.0V
0.8V
0.8V
0.45V
NOTE:
The float state is defined as the point at which a port 0 pin sinks 3.2mA or sources 400µA at the voltage test levels.
SU00216
Figure 54. AC Testing Input, Float Waveform
repeated START condition
START or repeated START condition
START condition
tSU;STA
STOP condition
tRD
0.7 VCC
SDA
(INPUT/OUTPUT)
0.3 VCC
tBUF
tFD
tRC
tFC
tSU;STO
0.7 VCC
SCL
(INPUT/OUTPUT)
0.3 VCC
tSU;DAT3
tHD;STA
tLOW
tHIGH
tSU;DAT1
tHD;DAT
tSU;DAT2
SU00107A
Figure 55. Timing SIO1 (I2C) Interface
1999 Mar 30
69
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
20
16
MAXIMUM ACTIVE MODE
12
IDD mA
8
TYPICAL ACTIVE MODE
4
MAXIMUM IDLE MODE
TYPICAL IDLE MODE
0
4
0
8
12
16
f (MHz)
SU01116
Figure 56. 16MHz Version Supply Current (IDD) as a Function of Frequency at XTAL1 (fOSC)
VDD
VDD
IDD
P1.6
P1.7
VDD
VDD
VDD
P0
RST
EA
STADC
(NC)
XTAL2
CLOCK SIGNAL
XTAL1
EW
AVSS
VSS
AVref–
SU00218
Figure 57. IDD Test Condition, Active Mode
All other pins are disconnected1
1. Active Mode:
a. The following pins must be forced to VDD: EA, RST, Port 0, and EW.
b. The following pins must be forced to VSS: STADC, AVss, and AVref–.
c. Ports 1.6 and 1.7 should be connected to VDD through resistors of sufficiently high value such that the sink current into these pins
cannot exceed the IOL1 spec of these pins.
d. The following pins must be disconnected: XTAL2 and all pins not specified above.
1999 Mar 30
70
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
VDD
P87C552
VDD
IDD
P1.6
P1.7
VDD
RST
VDD
STADC
P0
(NC)
XTAL2
CLOCK SIGNAL
XTAL1
EW
EA
AVSS
VSS
AVref–
SU00219
Figure 58. IDD Test Condition, Idle Mode
All other pins are disconnected2
2. Idle Mode:
a. The following pins must be forced to VDD: Port 0 and EW.
b. The following pins must be forced to VSS: RST, STADC, AVss, AVref–, and EA.
c. Ports 1.6 and 1.7 should be connected to VDD through resistors of sufficiently high value such that the sink current into these pins
cannot exceed the IOL1 spec of these pins. These pins must not have logic 0 written to them prior to this measurement.
d. The following pins must be disconnected: XTAL2 and all pins not specified above.
VDD–0.5
0.7VDD
0.5V
0.2VDD–0.1
tCHCL
tCHCX
tCLCH
tCLCX
tCLCL
SU00220
Figure 59. Clock Signal Waveform for IDD Tests in Active and Idle Modes
tCLCH = tCHCL = 5ns
VDD
VDD
IDD
P1.6
P1.7
VDD
VDD
RST
STADC
P0
(NC)
EW
XTAL2
EA
XTAL1
AVSS
VSS
AVref–
SU00221
Figure 60. IDD Test Condition, Power Down Mode
All other pins are disconnected. VDD = 2V to 5.5V3
3. Power Down Mode:
a. The following pins must be forced to VDD: Port 0 and EW.
b. The following pins must be forced to VSS: RST, STADC, XTAL1, AVss, AVref–, and EA.
c. Ports 1.6 and 1.7 should be connected to VDD through resistors of sufficiently high value such that the sink current into these pins
cannot exceed the IOL1 spec of these pins. These pins must not have logic 0 written to them prior to this measurement.
d. The following pins must be disconnected: XTAL2 and all pins not specified above.
1999 Mar 30
71
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
EPROM CHARACTERISTICS
Security Bits
The 87C552 contains three signature bytes that can be read and
used by an EPROM programming system to identify the device. The
signature bytes identify the device as an 87C552 manufactured by
Philips:
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 11) 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.
(030H) = 15H indicates manufactured by Philips Components
(031H) = 93H indicates 87C552
(60H) = 01H
Program Verification
When all three security bits are programmed, all of the conditions
above apply and all external program memory execution is disabled.
If security bits 2 or 3 have not been programmed, the on-chip
program memory can be read out for program verification.
If the 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.
Table 11. 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.
NOTES:
1. P – programmed. U – unprogrammed.
2. Any other combination of the security bits is not defined.
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.
1999 Mar 30
72
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM, capture/compare,
high I/O, low voltage (2.7V–5.5V), low power
PLCC68: plastic leaded chip carrier; 68 leads; pedestal
1999 Mar 30
73
P87C552
SOT188-3
Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM, capture/compare,
high I/O, low voltage (2.7V–5.5V), low power
P87C552
Data sheet status
Data sheet
status
Product
status
Definition [1]
Objective
specification
Development
This data sheet contains the design target or goal specifications for product development.
Specification may change in any manner without notice.
Preliminary
specification
Qualification
This data sheet contains preliminary data, and supplementary data will be published at a later date.
Philips Semiconductors reserves the right to make chages at any time without notice in order to
improve design and supply the best possible product.
Product
specification
Production
This data sheet contains final specifications. Philips Semiconductors reserves the right to make
changes at any time without notice in order to improve design and supply the best possible product.
[1] Please consult the most recently issued datasheet before initiating or completing a design.
Definitions
Short-form specification — The data in a short-form specification is extracted from a full data sheet with the same type number and title. For
detailed information see the relevant data sheet or data handbook.
Limiting values definition — Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one
or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or
at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended
periods may affect device reliability.
Application information — Applications that are described herein for any of these products are for illustrative purposes only. Philips
Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or
modification.
Disclaimers
Life support — These products are not designed for use in life support appliances, devices or systems where malfunction of these products can
reasonably be expected to result in personal injury. Philips Semiconductors customers using or selling these products for use in such applications
do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application.
Right to make changes — Philips Semiconductors reserves the right to make changes, without notice, in the products, including circuits, standard
cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no
responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these
products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless
otherwise specified.
 Copyright Philips Electronics North America Corporation 1999
All rights reserved. Printed in U.S.A.
Philips Semiconductors
811 East Arques Avenue
P.O. Box 3409
Sunnyvale, California 94088–3409
Telephone 800-234-7381
Date of release: 03-99
Document order number:
1999 Mar 30
74
9397 750 05504