80C51 8-bit microcontroller family
2K/64 OTP/ROM, low pin count
Preliminary specification
Supersedes data of 1998 Apr 23
IC20 Data Handbook
1999 Apr 15
Philips SemiconductorsPreliminary specification
80C51 8-bit microcontroller family
2K/64 OTP/ROM, low pin count
DESCRIPTION
The Philips 83C748/87C748 offers the advantages of the 80C51
architecture in a small package and at low cost.
The 8XC748 Microcontroller is fabricated with Philips high-density
CMOS technology. Philips epitaxial substrate minimizes CMOS
latch-up sensitivity.
The 8XC748 contains a 2k × 8 ROM (83C748) EPROM (87C748), a
64 × 8 RAM, 19 I/O lines, a 16-bit auto-reload counter/timer, a
four-source, fixed-priority level interrupt structure, and an on-chip
oscillator.
FEA TURES
•80C51 based architecture
•Small package sizes
– 24-pin DIP (300 mil “skinny DIP”)
– 24-pin Shrink Small Outline Package (SSOP)
– 28-pin PLCC
•87C748 available in erasable quartz lid or one-time programmable
plastic packages
•Wide oscillator frequency range: –3.5 to 16MHz
•Low power consumption:
– Normal operation: less than 11mA @ 5V, 12MHz
– Idle mode
– Power-down mode
•2k × 8 ROM (83C748)
2k × 8 EPROM (87C748)
•64 × 8 RAM
•16-bit auto reloadable counter/timer
•10-bit fixed-rate timer
•Boolean processor
•CMOS and TTL compatible
•Well suited for logic replacement, consumer and industrial
P83C748EBP NP87C748EBP NOTP0 to +70, Plastic Dual In-line Package3.5 to 16SOT222-1
P83C748EBA AP87C748EBA AOTP0 to +70, Plastic Leaded Chip Carrier3.5 to 16SOT261-3
P83C748EBD DBP87C748EBD DBOTP0 to +70, Shrink Small Outline Package3.5 to 16SOT340-1
NOTE:
1. OTP = One Time Programmable EPROM.
1999 Apr 15
2
FREQUENCY
MHz
DRAWING
NUMBER
Philips SemiconductorsPreliminary specification
80C51 8-bit microcontroller family
2K/64 OTP/ROM, low pin count
BLOCK DIAGRAM
V
CC
V
SS
RAM ADDR
REGISTER
B
REGISTER
RAM
ACC
TMP2
PSW
ALU
P0.0–P0.2
PORT 0
DRIVERS
PORT 0
LATCH
TMP1
PCONTCON
TH0TL0
RTH RTL
INTERRUPT AND
TIMER BLOCKS
STACK
POINTER
IE
ROM/
EPROM
83C748/87C748
PROGRAM
ADDRESS
REGISTER
BUFFER
PC
INCRE-
MENTER
RST
TIMING
AND
CONTROL
OSCILLATOR
X1
INSTRUCTION
PD
REGISTER
X2
PORT 1
LATCH
PORT 1
DRIVERS
P1.0–P1.7
PORT 3
LATCH
PORT 3
DRIVERS
P3.0–P3.7
PROGRAM
COUNTER
DPTR
SU00296
1999 Apr 15
3
Philips SemiconductorsPreliminary specification
80C51 8-bit microcontroller family
83C748/87C748
2K/64 OTP/ROM, low pin count
PIN DESCRIPTIONS
PIN NO.
MNEMONIC
V
SS
V
CC
P0.0–P0.28–69–7I/OPort 0: Port 0 is a 3-bit open-drain, bidirectional port. Port 0 pins that have 1s written to them float,
P1.0–P1.713–20 15–20,
P3.0–P3.75–1,
RST911IReset: A high on this pin for two machine cycles while the oscillator is running, resets the device.
X11113ICrystal 1: Input to the inverting oscillator amplifier and input to the internal clock generator circuits.
X21012OCrystal 2: Output from the inverting oscillator amplifier.
NOTE:
1. When P0.2 is at or close to 0 volts, it may affect the internal ROM operation. It is recommended that P0.2 be tied to V
(e.g. 2k).
ABSOLUTE MAXIMUM RATINGS
Storage temperature range–65 to +150°C
Voltage from V
Voltage from any pin to V
Power dissipation1.0W
Voltage on VPP pin to V
Maximum IOL per I/O pin10mA
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.
DIP/
SSOP
23–21
CC
LCCTYPENAME AND FUNCTION
1214ICircuit Ground Potential
2428ISupply voltage during normal, idle, and power-down operation.
and in that state can be used as high-impedance inputs. These pins are driven low if the port register
bit is written with a 0. The state of the pin can always be read from the port register by the program.
P0.0 and P0.1 are open drain bidirectional I/O pins. While these differ from “standard TTL”
characteristics, they are close enough for the pins to still be used as general-purpose I/O. Port 0
also provides alternate functions for programming the EPROM memory as follows:
67N/AVPP (P0.2) – Programming voltage input. (See Note 1).
78IOE/PGM (P0.1) – Input which specifies verify mode (output enable) or the program mode.
89IASEL (P0.0) – Input which indicates which bits of the EPROM address are applied to port 3.
ASEL = 1 high address byte available on port 3 (only the three least significant bits are used).
I/OPort 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. Port 1 pins that have 1s written
to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, port 1 pins
that are externally pulled low will source current because of the internal pull-ups. (See DC Electrical
Characteristics: I
accepts as inputs the value to program into the selected address during the program mode. Port 1
also serves the special function features of the 80C51 family as listed below:
I/OPort 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins that have 1s written
to them are pulled high by the internal pull-ups and can be used as inputs. As inputs, port 3 pins
that are externally being pulled low will source current because of the pull-ups. (See DC Electrical
Characteristics: I
programmed (or verified). The 11-bit address is multiplexed into this port as specified by P0.0/ASEL.
An internal diffused resistor to V
. After the device is reset, a 10-bit serial sequence, sent LSB first, applied to RESET, places
V
CC
the device in the programming state allowing programming address, data and V
programming or verification purposes. The RESET serial sequence must be synchronized with the
X1 input.
X1 also serves as the clock to strobe in a serial bit stream into RESET to place the device in the
programming state.
1, 2
PARAMETER
). Port 1 serves to output the addressed EPROM contents in the verify mode and
IL
). Port 3 also functions as the address input for the EPROM memory location to be
IL
permits a power-on RESET using only an external capacitor to
SS
to be applied for
PP
via a small pull-up
CC
RATINGUNIT
–0.5 to +6.5V
0 to +13.0V
1999 Apr 15
4
Philips SemiconductorsPreliminary specification
SYMBOL
PARAMETER
TEST CONDITIONS
UNIT
80C51 8-bit microcontroller family
83C748/87C748
2K/64 OTP/ROM, low pin count
DC ELECTRICAL CHARACTERISTICS
T
= 0°C to +70°C, VCC = 5V ±10%, VSS = 0V
amb
V
IL
V
IH
V
IH1
V
IL1
V
IH2
V
OL
V
OL1
V
OH
V
OL2
CCapacitance10pF
I
IL
I
TL
I
LI
R
RST
C
IO
I
PD
V
PP
I
PP
I
CC
NOTES:
1. Parameters are valid over operating temperature range unless otherwise specified. All voltages are with respect to V
noted.
2. Under steady state (non-transient) conditions, I
If I
OL
test conditions.
3. Pins of ports 1 and 3 source a transition current when they are being externally driven from 1 to 0. The transition current reaches its
maximum value when V
4. Power-down I
5. Active I
RST = port 0 = V
6. Idle I
port 0 = V
Input low voltage–0.50.2VDD–0.1V
Input high voltage, except X1, RST0.2VCC+0.9VCC+0.5V
Input high voltage, X1, RST0.7V
P0.2
Input low voltage–0.50.3V
Input high voltage0.7V
Output low voltage, ports 1 and 3IOL = 1.6mA
Output low voltage, port 0.2IOL = 3.2mA
Output high voltage, ports 1 and 3IOH = –60µA2.4V
Port 0.0 and 0.1 – Drivers
Output low voltageIOL = 3mA0.4V
Driver, receiver combined:(over VCC range)
Logical 0 input current, ports 1 and 3VIN = 0.45V–50µA
Logical 1 to 0 transition current, ports 1 and 3
Input leakage current, port 00.45 < VIN < V
Internal pull-down resistor25175kΩ
Pin capacitance
Power-down current
4
VPP program voltage (for 87C748 only)
Program current (for 87C748 only)VPP = 13.0V50mA
Supply current (see Figure 2)
Maximum I
Maximum I
Maximum total I
exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater than the listed
CC
is measured with all output pins disconnected; X1 driven with t
CC
is measured with all output pins disconnected; X1 driven with t
CC
; RST = VSS.
CC
per port pin:10mA
OL
per 8-bit port:26mA
OL
for all outputs:67mA
OL
is approximately 2V .
IN
is measured with all output pins disconnected; port 0 = VCC; X2, X1 n.c.; RST = VSS.
. ICC will be slightly higher if a crystal oscillator is used.
High time2020ns
Low time2020ns
Rise time2020ns
Fall time2020ns
NOTES:
1. Parameters are valid over operating temperature range unless otherwise specified. All voltages are with respect to V
noted.
2. Load capacitance for ports = 80pF.
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:
C – Clock
D – Input data
H – Logic level high
1, 2
16MHz CLOCKVARIABLE CLOCK
3.516MHz
L – Logic level low
Q – Output data
T – Time
V – Valid
X – No longer a valid logic level
Z – Float
unless otherwise
SS
t
CHCL
t
CLCX
t
CLCL
t
CLCH
t
CHCX
SU00297
VCC –0.5
0.45V
0.2 V
0.2 V
+ 0.9
CC
– 0.1
CC
Figure 1. External Clock Drive
ROM CODE SUBMISSION
When submitting ROM code for the 83C748, the following must be specified:
1. 2k byte user ROM data
ADDRESS
0000H to 07FFHDATA7:0User ROM Data
CONTENTBIT(S)COMMENT
1999 Apr 15
6
Philips SemiconductorsPreliminary specification
80C51 8-bit microcontroller family
2K/64 OTP/ROM, low pin count
22
20
18
16
14
I
(mA)
CC
12
10
8
6
4
2
MAX ACTIVE I
TYP ACTIVE I
MAX IDLE I
TYP IDLE I
CC
CC
CC
6
CC
6
83C748/87C748
5
5
4MHz8MHz12MHz 16MHz
Figure 2. ICC vs. FREQ
Maximum I
values taken at VCC max and worst case temperature.
CC
Typical I
values taken at VCC = 5.0V and 25°C.
CC
Notes 5 and 6 refer to DC Electrical Characteristics.
OSCILLA T OR CHARACTERISTICS
X1 and X2 are the input and output, respectively, of an inverting
amplifier which can be configured for use as an on-chip oscillator.
To drive the device from an external clock source, X1 should be
driven while X2 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.
RESET
A reset is accomplished by holding the RST pin high for at least two
machine cycles (24 oscillator periods), while the oscillator is running.
To insure a good power-up reset, the RST pin must be high long
enough to allow the oscillator time to start up (normally a few
milliseconds) plus two machine cycles. At power-up, the voltage on
V
and RST must come up at the same time for a proper start-up.
CC
IDLE MODE
In idle mode, the CPU puts itself to sleep while all of the on-chip
peripherals stay active. The instruction to invoke the idle mode is the
last instruction executed in the normal operating mode before the
FREQ
SU00298
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.
POWER-DOWN MODE
In the power-down mode, the oscillator is stopped and the
instruction to invoke power-down is the last instruction executed.
Only the contents of the on-chip RAM are preserved. A hardware
reset is the only way to terminate the power-down mode. the control
bits for the reduced power modes are in the special function register
PCON.
Table 1. External Pin Status During Idle and
Power-Down Modes
MODEPort 0Port 1Port 2
IdleDataDataData
Power-downDataDataData
1999 Apr 15
7
Philips SemiconductorsPreliminary specification
80C51 8-bit microcontroller family
2K/64 OTP/ROM, low pin count
DIFFERENCES BETWEEN THE 8XC748 AND THE
80C51
Memory Organization
The central processing unit (CPU) manipulates operands in two
address spaces as shown in Figure 3. The part’s internal memory
space consists of 2k bytes of program memory, and 64 bytes of data
RAM overlapped with the 128-byte special function register area.
The differences from the 80C51 are in RAM size (64 bytes vs. 128
bytes), in external RAM access (not available on the 83C748), in
internal ROM size (2k bytes vs. 4k bytes), and in external program
memory expansion (not available on the 83C748). The 128-byte
special function register (SFR) space is accessed as on the 80C51
with some of the registers having been changed to reflect changes
in the 83C748 peripheral functions. The stack may be located
anywhere in internal RAM by loading the 8-bit stack pointer (SP). It
should be noted that stack depth is limited to 64 bytes, the amount
of available RAM. A reset loads the stack pointer with 07 (which is
pre-incremented on a PUSH instruction).
Program Memory
On the 8XC748, program memory is 2048 bytes long and is not
externally expandable, so the 80C51 instructions MOVX, LJMP, and
LCALL are not implemented. The only fixed locations in program
memory are the addresses at which execution is taken up in
response to reset and interrupts, which are as follows:
The 8XC748 has one counter/timer called timer/counter 0. Its
operation is similar to mode 2 operation on the 80C51, but is
extended to 16 bits with 16 bits of autoload. The controls for this
counter are centralized in a single register called TCON.
Timer I is available for use as a fixed 10-bit time-base, or as a
watchdog.
Counter Timer – Special Function Register
The counter/timer has only one mode of operation, so the TMOD
SFR is not used. There is also only one counter/timer, so there is no
need for the TL1 and TH1 SFRs found on the 80C51. These have
been replaced on the 8XC748 by RTL and RTH, the counter/timer
reload registers. Table 2 shows the special function registers, their
locations, and reset values.
Program Memory
003
013
83C748/87C748
Interrupt Subsystem – Fixed Priority
The IP register and the 2-level interrupt system of the 80C51 are
eliminated. Simultaneous interrupt conditions are resolved by a
single-level, fixed priority as follows:
Highest priority:Pin INT0
Counter/timer flag 0
Pin INT1
Lowest priority:Timer I
Special Function Register – Interrupt Subsystem
Because the interrupt structure is single level on the 83C748, there
is no need for the IP SFR, so it is not used.
Special Function Register –
Serial Communications
The 8XC748 contains many of the special function registers (SFR)
that are found on the 80C51. Due to the different peripheral features
on the 8XC748, there are several additional SFRs. Since the UART
found on 80C51 has been removed, the UART SFRs SCON and
SBUF have also been removed.
I/O Port Latches (P0, P1, P3)
The port latches function the same as those on the 80C51. Since
there is no port 2 on the 83C748, the P2 latch is not used. Port 0 on
the 83C748 has only 3 bits, so only 3 bits of the P0 SFR have a
useful function.
Data Pointer (DPTR)
The data pointer (DPTR) consists of a high byte (DPH) and a low
byte (DPL). In the 80C51 this register allows the access of external
data memory using the MOVX instruction. Since the 83C748 does
not support MOVX or external memory accesses, this register is
generally used as a 16-bit offset pointer of the accumulator in a
MOVC instruction. DPTR may also be manipulated as two
independent 8-bit registers.
WR––CLRTITIRUN––––
RTL#Timer low reload8BH00H
RTH#Timer high reload8DH00H
* SFRs are bit addressable.
# SFRs are modified from or added to the 80C51 SFRs.
I/O Port Structure
The 8XC748 has two 8-bit ports (ports 1 and 3) and one 3-bit port
(port 0). All three ports on the 8XC748 are bidirectional. Each
consists of a latch (special function register P0, P1, P3), an output
driver, and an input buffer. Three port 1 pins and two port 0 pins are
multifunctional. In addition to being port pins, these pins serve the
function of special features as follows:
Ports 1 and 3 are identical in structure to the same ports on the
80C51. The structure of port 0 on the 8XC748 is similar to that of the
80C51 but does not include address/data input and output circuitry.
As on the 80C51, ports 1 and 3 are quasi-bidirectional while port 0 is
bidirectional with no internal pullups.
Timer/Counter
The 8XC748 has two timers: a 16-bit timer/counter and a 10-bit
fixed-rate timer. The 16-bit timer/counter’s operation is similar to
mode 2 operation on the 80C51, but is extended to 16 bits. The
timer/counter is clocked by either 1/12 the oscillator frequency or by
transitions on the T0 pin. The C/T pin in special function register
TCON selects between these two modes. When the TCON TR bit is
set, the timer/counter is enabled. Register pair TH and TL are
incremented by the clock source. When the register pair overflows,
the register pair is reloaded with the values in registers RTH and
RTL. The value in the reload registers is left unchanged. See the
83C748 counter/timer block diagram in Figure 4. The TF bit in
special function register TCON is set on counter overflow and, if the
interrupt is enabled, will generate an interrupt.
1999 Apr 15
9
Philips SemiconductorsPreliminary specification
80C51 8-bit microcontroller family
2K/64 OTP/ROM, low pin count
TCON Register
MSBLSB
GATE
GATE 1 – Timer/counter is enabled only when INT0 pin is high,
C/T1 – Counter/timer operation from T0 pin.
TF1 – Set on overflow of TH.
TR1 – Timer/counter enabled.
IE01 – Edge detected in INT0
IT01 – INT0
IE11 – Edge detected on INT1
IT11 – INT1
These flags are functionally identical to the corresponding 80C51
flags, except that there is only one timer on the 83C748 and the
flags are therefore combined into one register.
Note that the positions of the IE0/IT0 and IE1/IT1 bits are transposed
from the positions used in the standard 80C51 TCON register.
Timer I Implementation
Timer I is clocked once per machine cycle, which is the oscillator
frequency divided by 12. The timer operation is enabled by setting
the TIRUN bit (bit 4) in the I2CFG register. Writing a 0 into the
TIRUN bit will stop and clear the timer. The timer is 10 bits wide, and
when it reaches the terminal count of 1024, it carries out and sets
the Timer I interrupt flag. An interrupt will occur if the Timer I
interrupt is enabled by bit ETI (bit 4) of the Interrupt Enable (IE)
register, and global interrupts are enabled by bit EA (bit 7) of the
same IE register.
The vector address for the Timer I interrupt is 1Bhex, and the
interrupt service routine must start at this address. As with all 8051
family microcontrollers, only the Program Counter is pushed onto
the stack upon interrupt (other registers that are used both by the
interrupt service routine and elsewhere must be explicitly saved).
The Timer I interrupt flag is cleared by setting the CKRTI bit (bit 5 of
the I1CFG register. For more information, see application note
AN427.
C/TTFTRIE0IT0IE1IT1
and TR is 1.
0 – Timer/counter is enabled when TR is 1.
0 – Timer operation from internal clock.
0 – Cleared when processor vectors to interrupt routine
and by reset.
0 – Timer/counter disabled.
.
is edge triggered.
0 – INT0
is level sensitive.
.
is edge triggered.
0 – INT1
is level sensitive.
83C748/87C748
Interrupts
The interrupt structure is a four-source, one-level interrupt system.
Interrupt sources common to the 80C51 are the external interrupts
, INT1) and the timer/counter interrupt (ET0). Timer I interrupt
(INT0
(ETI) is the other interrupt source. The interrupt sources are listed
below in their order of polling sequence priority.
Upon interrupt or reset the program counter is loaded with specific
values for the appropriate interrupt service routine in program
memory. These values are:
The interrupt enable register (IE) is used to individually enable or
disable the four sources. Bit EA
be used to globally enable or disable all interrupt sources. The
interrupt enable register is described below. All other interrupt details
are based on the 80C51 interrupt architecture.
Interrupt Enable Register
EAXX—ETIEX1ET0EX0
Symbol PositionFunction
EA
IE.7Disables all interrupts. If EA = 0, no interrupt
will be acknowledged. If EA = 1, each
interrupt source is individually enabled or
disabled by setting or clearing its enable bit
–IE.6Reserved
–IE.5Reserved
–IE.4Reserved
ETIIE.3Enables or disables the Timer I overflow
interrupt. If ET1 = 0, the Timer I interrupt is
disabled.
EX1IE.2Enables or disables external interrupt 1.
If EX1 = 0, external interrupt 1 is disabled.
ET0IE.1Enables or disables the Timer 0 overflow
interrupt. If ET0 = 0, theTimer 0 interrupt is
disabled.
EX0IE.0Enables or disables external interrupt 0.
If EX0 = 0, external interrupt 0 is disabled.
in the interrupt enable register can
1999 Apr 15
INT0
OSC
T0 Pin
Gate
Pin
÷ 12
C/T = 0
C/T = 1
TR
TLTHTF
Reload
RTLRTH
Int.
SU00300
Figure 4. 83C748 Counter/Timer Block Diagram
10
Philips SemiconductorsPreliminary specification
80C51 8-bit microcontroller family
2K/64 OTP/ROM, low pin count
The 87C748 is programmed by using a modified Quick-Pulse
Programming algorithm similar to that used for devices such as the
87C451 and 87C51. It differs from these devices in that a serial data
stream is used to place the 87C748 in the programming mode.
Figure 5 shows a block diagram of the programming configuration
for the 87C748. Port pin P0.2 is used as the programming voltage
supply input (V
(PGM/) signal. This pin is used for the 25 programming pulses.
Port 3 is used as the address input for the byte to be programmed
and accepts both the high and low components of the eleven bit
address. Multiplexing of these address components is performed
using the ASEL input. The user should drive the ASEL input high
and then drive port 3 with the high order bits of the address. ASEL
should remain high for at least 13 clock cycles. ASEL may then be
driven low which latches the high order bits of the address internally.
the high address should remain on port 3 for at least two clock
cycles after ASEL is driven low. Port 3 may then be driven with the
low byte of the address. The low address will be internally stable 13
clock cycles later. The address will remain stable provided that the
low byte placed on port 3 is held stable and ASEL is kept low. Note:
ASEL needs to be pulsed high only to change the high byte of the
address.
Port 1 is used as a bidirectional data bus during programming and
verify operations. During programming mode, it accepts the byte to
be programmed. During verify mode, it provides the contents of the
EPROM location specified by the address which has been supplied
to Port 3.
The XTAL1 pin is the oscillator input and receives the master system
clock. This clock should be between 1.2 and 6MHz.
The RESET pin is used to accept the serial data stream that places
the 87C748 into various programming modes. This pattern consists
of a 10-bit code with the LSB sent first. Each bit is synchronized to
the clock input, X1.
Programming Operation
Figures 6 and 7 show the timing diagrams for the program/verify
cycle. RESET should initially be held high for at least two machine
cycles. P0.1 (PGM/) and P0.2 (V
RESET operation. At this point, these pins function as normal
quasi-bidirectional I/O ports and the programming equipment may
pull these lines low. However, prior to sending the 10-bit code on the
RESET pin, the programming equipment should drive these pins
high (V
IH
for the data stream which places the 87C748 in the programming
mode. Data bits are sampled during the clock high time and thus
should only change during the time that the clock is low. Following
transmission of the last data bit, the RESET pin should be held low.
Next the address information for the location to be programmed is
placed on port 3 and ASEL is used to perform the address
multiplexing, as previously described. At this time, port 1 functions
as an output.
A high voltage V
(This sets Port 1 as an input port). The data to be programmed into
signal). Port pin P0.1 is used as the program
PP
) will be at VOH as a result of the
PP
). The RESET pin may now be used as the serial data input
level is then applied to the VPP input (P0.2).
PP
83C748/87C748
the EPROM array is then placed on Port 1. This is followed by a
series of programming pulses applied to the PGM/ pin (P0.1). These
pulses are created by driving P0.1 low and then high. This pulse is
repeated until a total of 25 programming pulses have occurred. At
the conclusion of the last pulse, the PGM/ signal should remain high.
The V
signal may now be driven to the VOH level, placing the
PP
87C748 in the verify mode. (Port 1 is now used as an output port).
After four machine cycles (48 clock periods), the contents of the
addressed location in the EPROM array will appear on Port 1.
The next programming cycle may now be initiated by placing the
address information at the inputs of the multiplexed buffers, driving
the V
pin to the VPP voltage level, providing the byte to be
PP
programmed to Port1 and issuing the 26 programming pulses on the
PGM/ pin, bringing V
byte.
Programming Modes
The 87C748 has four programming features incorporated within its
EPROM array. These include the USER EPROM for storage of the
application’s code, a 16-byte encryption key array and two security
bits. Programming and verification of these four elements are
selected by a combination of the serial data stream applied to the
RESET pin and the voltage levels applied to port pins P0.1 and
P0.2. The various combinations are shown in Table 3.
Table 3. Implementing Program/Verify Modes
OPERATIONSERIAL
Program user EPROM296H–*V
Verify user EPROM296HV
Program key EPROM292H–*V
Verify key EPROM292HV
Program security bit 129AH–*V
Program security bit 2298H–*V
Verify security bits29AHV
NOTE:
* Pulsed from V
Encryption Key Table
The 87C748 includes a 16-byte EPROM array that is programmable
by the end user. The contents of this array can then be used to
encrypt the program memory contents during a program memory
verify operation. When a program memory verify operation is
performed, the contents of the program memory location is
XNOR’ed with one of the bytes in the 16-byte encryption table. The
resulting data pattern is then provided to port 1 as the verify data.
The encryption mechanism can be disable, in essence, by leaving
the bytes in the encryption table in their erased state (FFH) since
the XNOR product of a bit with a logical one will result in the original
bit. The encryption bytes are mapped with the code memory in
16-byte groups. the first byte in code memory will be encrypted with
the first byte in the encryption table; the second byte in code
memory will be encrypted with the second byte in the encryption
table and so forth up to and including the 16the byte. The encryption
repeats in 16-byte groups; the 17th byte in the code memory will be
encrypted with the first byte in the encryption table, and so forth.
back down to the VC level and verifying the
PP
CODE
to VIL and returned to VIH.
IH
P0.1
(PGM/)
IH
IH
IH
P0.2
(VPP)
PP
V
IH
PP
V
IH
PP
PP
V
IH
1999 Apr 15
11
Philips SemiconductorsPreliminary specification
80C51 8-bit microcontroller family
2K/64 OTP/ROM, low pin count
Security Bits
Two security bits, security bit 1 and security bit 2, are provided to
limit access to the USER EPROM and encryption key arrays.
Security bit 1 is the program inhibit bit, and once programmed
performs the following functions:
1. Additional programming of the USER EPROM is inhibited.
2. Additional programming of the encryption key is inhibited.
3. Verification of the encryption key is inhibited.
4. Verification of the USER EPROM and the security bit levels may
still be performed.
(If the encryption key array is being used, this security bit should be
programmed by the user to prevent unauthorized parties from
reprogramming the encryption key to all logical zero bits. Such
programming would provide data during a verify cycle that is the
logical complement of the USER EPROM contents).
EPROM PROGRAMMING AND VERIFICATION
T
= 21°C to +27°C, VCC = 5V ±10%, VSS = 0V
amb
SYMBOL
1/t
CLCL
t
AVGL
t
GHAX
t
DVGL
t
GHDX
t
SHGL
t
GHSL
t
GLGH
t
AVQV
t
GHGL
t
MASEL
t
HAHLD
t
HASET
t
ADSTA
1
2
Oscillator/clock frequency1.26MHz
Address setup to P0.1 (PROG–) low10µs + 24t
Address hold after P0.1 (PROG–) high48t
Data setup to P0.1 (PROG–) low38t
Data hold after P0.1 (PROG–) high36t
VPP setup to P0.1 (PROG–) low10µs
VPP hold after P0.1 (PROG–)10µs
P0.1 (PROG–) width90110µs
VPP low (VCC) to data valid48t
P0.1 (PROG–) high to P0.1 (PROG–) low10µs
ASEL high time13t
Address hold time2t
Address setup to ASEL13t
Low address to valid data48t
NOTES:
1. Address should be valid at least 24t
2. For a pure verify mode, i.e., no program mode in between, t
PARAMETERMINMAXUNIT
before the rising edge of P0.2 (VPP).
CLCL
AVQV
83C748/87C748
Security bit 2, the verify inhibit bit, prevents verification of both the
USER EPROM array and the encryption key arrays. The security bit
levels may still be verified.
Programming and Verifying Security Bits
Security bits are programmed employing the same techniques used
to program the USER EPROM and KEY arrays using serial data
streams and logic levels on port pins indicated in Table 3. When
programming either security bit, it is not necessary to provide
address or data information to the 87C748 on ports 1 and 3.
Verification occurs in a similar manner using the RESET serial
stream shown in Table 3. Port 3 is not required to be driven and the
results of the verify operation will appear on ports 1.6 and 1.7.
Ports 1.7 contains the security bit 1 data and is a logical one if
programmed and a logical zero if not programmed. Likewise, P1.6
contains the security bit 2 data and is a logical one if programmed
and a logical zero if not programmed.
CLCL
CLCL
CLCL
CLCL
CLCL
CLCL
CLCL
CLCL
CLCL
is 14t
CLCL
maximum.
1999 Apr 15
12
Philips SemiconductorsPreliminary specification
80C51 8-bit microcontroller family
2K/64 OTP/ROM, low pin count
This data sheet contains the design target or goal specifications for product development.
Specification may change in any manner without notice.
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.
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]
83C748/87C748
[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.
Philips Semiconductors
811 East Arques Avenue
P.O. Box 3409
Sunnyvale, California 94088–3409
Telephone 800-234-7381
Copyright Philips Electronics North America Corporation 1999
All rights reserved. Printed in U.S.A.
Date of release: 04-99
Document order number:9397 750 05736
1999 Apr 15
18
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