The W78C52D microcontroller supplies a wider frequency and supply voltage range than most 8-bit
microcontrollers on the market. It is compatible with the industry standard 80C52 microcontroller
series. The W78C52D contains four 8-bit bidirectional parallel ports, one extra 4-bit bit-addressable
I/O port (Port 4) and two additional external interrupts (
watchdog timer and a serial port. These peripherals are supported by a eight-source, two-level
interrupt capability. There are 256 bytes of RAM and an 8K byte mask ROM for application programs.
The W78C52D microcontroller has two power reduction modes, idle mode and power-down mode,
both of which are software selectable. The idle mode turns off the processor clock but allows for
continued peripheral operation. The power-down mode stops the crystal oscillator for minimum power
consumption. The external clock can be stopped at any time and in any state without affecting the
processor.
FEATURES
• Fully static design
• Supply voltage of 4.5V to 5.5V
•
DC-40 MHz operation
• 256 bytes of on-chip scratchpad RAM
• 8K bytes of on-chip mask ROM
• 64K bytes program memory address space
• 64K bytes data memory address space
• Four 8-bit bidirectional ports
• Three 16-bit timer/counters
• One full duplex serial port
• Eight-source, two-level interrupt capability
• One extra 4-bit bit-addressable I/O port
, INT3 ), three 16-bit timer/counters, one
• Two additional external interrupts
• Watchdog timer
• EMI reduction mode
•
Built-in power management
• Code protection
• Packages:
− DIP 40: W78C52D-24/40
− PLCC 44: W78C52DP-24/40
− QFP 44: W78C52DF-24/40
INT2 / INT3
Publication Release Date: December 1998
- 1 -Revision A1
PIN CONFIGURATIONS
40-Pin DIP (W78C52D)
T2, P1.0
T2EX, P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
RST
RXD, P3.0
TXD, P3.1
INT0, P3.2
INT1, P3.3
T0, P3.4
T1, P3.5
WR, P3.6
RD, P3.7
XTAL2
XTAL1
VSS
Preliminary W78C52D
VDD1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
P0.0, AD0
38
P0.1, AD1
P0.2, AD2
37
36
P0.3, AD3
P0.4, AD4
35
34
P0.5, AD5
P0.6, AD6
33
32
P0.7, AD7
31
EA
30
ALE
29
PSEN
28
P2.7, A15
27
P2.6, A14
26
P2.5, A13
P2.4, A12
25
24
P2.3, A11
P2.2, A10
23
22
P2.1, A9
P2.0, A8
21
44-Pin PLCC (W78C52DP)
P
P
P
1
1
1
.
.
.
2
3
4
6543
7
P1.5
8
P1.6
9
P1.7
10
RST
RXD, P3.0
INT2, P4.3
TXD, P3.1
INT0, P3.2
INT1, P3.3
T0, P3.4
T1, P3.5
11
12
13
14
15
16
17
X
P
P
T
3
3
A
.
.
L
7
6
2
,
,
/
/
R
W
D
R
/
T
I
2
N
T
E
T
2
X
3
,
,
,
P
P
P
1
1
4
.
.
.
0
1
2
2 1 44 43 42
X
V
P
T
S
4
A
S
.
L
0
1
44-Pin QFP (W78C52DF)
/
T
I
2
N
T
E
A
A
A
A
D
D
D
D
3
1
2
0
,
,
,
,
P
P
P
P
0
0
V
0
0
.
.
D
.
.
3
1
D
2
0
40
41
39
P0.4, AD4
38
P0.5, AD5
37
P0.6, AD6
36
P0.7, AD7
35
EA
34
P4.1
33
ALE
32
PSEN
31
P2.7, A15
30
P2.6, A14
29
P2.5, A13
2827262524232221201918
P
P
P
P
P
2
2
2
2
2
.
0
,
A
8
.
.
.
.
4
3
2
1
,
,
,
,
A
A
A
A
1
1
9
1
2
1
0
P1.5
P1.6
P1.7
RST
RXD, P3.0
TXD, P3.1
INT0, P3.2
INT1, P3.3
T0, P3.4
T1, P3.5
1
2
3
4
5
6
7
8
9
10
11
P
1
.
4
44
12
P
3
.
6
,
/
W
R
P
1
.
3
43 42 41
P
3
.
7
,
/
R
D
2
X
,
,
P
P
P
1
1
1
.
.
.
0
2
1
40 39 38 37 36 35
V
X
X
S
T
T
A
S
A
L
L
1
2
T
3
,
P
V
4
D
.
D
2
P
P
2
4
.
.
0
0
,
A
8
A
A
A
A
D
D
D
D
3
2
1
0
,
,
,
,
P
P
P
P
0
0
0
0
.
.
.
.
3
2
1
0
34
33
P0.4, AD4
32
P0.5, AD5
31
P0.6, AD6
30
P0.7, AD7
29
EA
28
P4.1INT2, P4.3
27
ALE
26
PSEN
25
P2.7, A15
24
P2.6, A14
23
P2.5, A13
22212019181716151413
P
P
P
P
2
2
2
2
.
.
.
.
3
4
2
1
,
,
,
,
A
A
A
A
1
1
1
9
2
1
0
- 2 -
Preliminary W78C52D
EA
PIN DESCRIPTION
P0.0−P0.7
Port 0, Bits 0 through 7. Port 0 is a bidirectional I/O port. This port also provides a multiplexed low
order address/data bus during accesses to external memory.
P1.0−P1.7
Port 1, Bits 0 through 7. Port 1 is a bidirectional I/O port with internal pull-ups. Pins P1.0 and P1.1
also serve as T2 (Timer 2 external input) and T2EX (Timer 2 capture/reload trigger), respectively.
P2.7
−
P2.0
Port 2, Bits 0 through 7. Port 2 is a bidirectional I/O port with internal pull-ups. This port also provides
the upper address bits for accesses to external memory.
P3.0−P3.7
Port 3, Bits 0 through 7. Port 3 is a bidirectional I/O port with internal pull-ups. All bits have alternate
functions, which are described below:
PINALTERNATE FUNCTION
P3.0RXD Serial Receive Data
P3.1TXD Serial Transmit Data
P3.2
P3.3
P3.4T0 Timer 0 Input
P3.5T1 Timer 1 Input
P3.6
P3.7
INT0 External Interrupt 0
INT1 External Interrupt 1
WR Data Write Strobe
RD Data Read Strobe
P4.0
−
P4.3
Another bit-addressable bidirectional I/O port P4. P4.3 and P4.2 are alternative function pins. It can
be used as general I/O pins or external interrupt input sources (
External Address Input, active low. This pin forces the processor to execute out of external ROM.
This pin should be kept low for all W78C31 operations.
RST
Reset Input, active high. This pin resets the processor. It must be kept high for at least two machine
cycles in order to be recognized by the processor.
ALE
Address Latch Enable Output, active high. ALE is used to enable the address latch that separates the
address from the data on Port 0. ALE runs at 1/6th of the oscillator frequency. A single ALE pulse is
skipped during external data memory accesses. ALE goes to a high impedance state during reset with
a weak pull-up.
- 3 -Revision A1
INT2 / INT3 ).
Publication Release Date: December 1998
Preliminary W78C52D
PSEN
PSEN
Program Store Enable Output, active low. PSEN enables the external ROM onto the Port 0
address/data bus during fetch and MOVC operations.
reset with a weak pull-up.
XTAL1
Crystal 1. This is the crystal oscillator input. This pin may be driven by an external clock.
XTAL2
Crystal 2. This is the crystal oscillator output. It is the inversion of XTAL1.
VSS, VDD
Power Supplies. These are the chip ground and positive supplies.
BLOCK DIAGRAM
goes to a high impedance state during
P1.0
~
P1.7
P3.0
~
P3.7
P4.0
~
P4.3
INT2
INT3
Port
1
Port
Port
Port 1
Latch
ACC
Interrupt
Timer
2
Timer
0
Timer
1
UART
3
4
Port 3
Latch
Port 4
Latch
XTAL1PSENALEGNDVDDRSTXTAL2
Oscillator
PSW
Instruction
Decoder
&
Sequencer
Bus & Clock
Controller
ALU
Reset Block
T2T1
SFR RAM
Address
256 bytes
RAM & SFR
8K bytes
ROM
Watchdog
Timer
B
Stack
Pointer
Power control
Port 0
Latch
DPTR
Temp Reg.
PC
Incrementor
Addr. Reg.
Port 2
Latch
Port
0
Port
2
P0.0
~
P0.7
P2.0
~
P2.7
- 4 -
Preliminary W78C52D
FUNCTIONAL DESCRIPTION
The W78C52D architecture consists of a core controller surrounded by various registers, five general
purpose I/O ports, 256 bytes of RAM, three timer/counters, one watchdog timer and a serial port. The
processor supports 111 different opcodes and references both a 64K program address space and a
64 K data storage space.
Timers 0, 1, and 2
Timers 0, 1, and 2 each consist of two 8-bit data registers. These are called TL0 and TH0 for Timer
0, TL1 and TH1 for Timer 1, and TL2 and TH2 for Timer 2. The TCON and TMOD registers provide
control functions for timers 0, 1. The T2CON register provides control functions for Timer 2. RCAP2H
and RCAP2L are used as reload/capture registers for Timer 2. The operations of Timer 0 and Timer
1 are the same as in the W78C51. Timer 2 is a special feature of the W78C52D: it is a 16-bit
timer/counter that is configured and controlled by the T2CON register. Like Timers 0 and 1, Timer 2
can operate as either an external event counter or as an internal timer, depending on the setting of
bit C/T2 in T2CON. Timer 2 has three operating modes: capture, auto-reload, and baud rate
generator. The clock speed at capture or auto-reload mode is the same as that of Timers 0 and 1.
Clock
The W78C52D is designed to be used with either a crystal oscillator or an external clock. Internally,
the clock is divided by two before it is used. This makes the W78C52D relatively insensitive to duty
cycle variations in the clock.
Crystal Oscillator
The W78C52D incorporates a built-in crystal oscillator. To make the oscillator work, a crystal must be
connected across pins XTAL1 and XTAL2. In addition, a load capacitor must be connected from each
pin to ground, and a resistor must also be connected from XTAL1 to XTAL2 to provide a DC bias
when the crystal frequency is above 24 MHz.
External Clock
An external clock should be connected to pin XTAL1. Pin XTAL2 should be left unconnected. The
XTAL1 input is a CMOS-type input, as required by the crystal oscillator. As a result, the external clock
signal should have an input one level of greater than 3.5 volts when V
= 5 volts.
DD
Power Management
Idle Mode
The idle mode is entered by setting the IDL bit in the PCON register. In the idle mode, the internal
clock to the processor is stopped. The peripherals and the interrupt logic continue to be clocked. The
processor will exit idle mode when either an interrupt or a reset occurs.
Power-down Mode
When the PD bit of the PCON register is set, the processor enters the power-down mode. In this
mode all of the clocks, including the oscillator are stopped. The only way to exit power-down mode is
by a reset.
Reset
The external RESET signal is sampled at S5P2. To take effect, it must be held high for at least two
machine cycles while the oscillator is running. An internal trigger circuit in the reset line is used to
Publication Release Date: December 1998
- 5 -Revision A1
Preliminary W78C52D
INT2
deglitch the reset line when the W78C52D is used with an external RC network. The reset logic also
has a special glitch removal circuit that ignores glitches on the reset line. During reset, the ports are
initialized to FFH, the stack pointer to 07H, PCON (with the exception of bit 4) to 00H, and all of the
other SFR registers except SBUF to 00H. SBUF is not reset.
New Defined Peripheral
In order to be more suitable for I/O, an extra 4-bit bit-addressable port P4 and two external interrupts
INT2 , INT3 have been added to either the PLCC or QFP package. And description follows:
1.
Two additional external interrupts,
interrupt 0 and 1 in the standard 80C52. The functions/status of these interrupts are
determined/shown by the bits in the XICON (External Interrupt Control) register. The XICON register
is bit-addressable but is not a standard register in the standard 80C52. Its address is at 0C0H. To
set/clear bits in the XICON register, one can use the "SETB (/CLR) bit" instruction. For example,
"SETB 0C2H" sets the EX2 bit of XICON.
***XICON - external interrupt control (C0H)
PX3: External interrupt 3 priority high if set
EX3: External interrupt 3 enable if set
IE3: If IT3 = 1, IE3 is set/cleared automatically by hardware when interrupt is detected/serviced
IT3: External interrupt 3 is falling-edge/low-level triggered when this bit is set/cleared by software
PX2: External interrupt 2 priority high if set
EX2: External interrupt 2 enable if set
IE2: If IT2 = 1, IE2 is set/cleared automatically by hardware when interrupt is detected/serviced
IT2: External interrupt 2 is falling-edge/low-level triggered when this bit is set/cleared by software
Eight-source interrupt informations:
/ INT3
INT2 and INT3 , whose functions are similar to those of external
PX3EX3IE3IT3PX2EX2IE2IT2
INTERRUPT
SOURCE
External Interrupt 003H0 (highest)IE.0TCON.0
Timer/Counter 00BH1IE.1-
External Interrupt 113H2IE.2TCON.2
Timer/Counter 11BH3IE.3-
Serial Port23H4IE.4-
Timer/Counter 22BH5IE.5-
External Interrupt 233H6XICON.2XICON.0
External Interrupt 33BH7 (lowest)XICON.6XICON.3
VECTOR
ADDRESS
POLLING
SEQUENCE WITHIN
PRIORITY LEVEL
ENABLE
REQUIRED
SETTINGS
INTERRUPT
TYPE
EDGE/LEVEL
- 6 -
Preliminary W78C52D
2. PORT4
Another bit-addressable port P4 is also available and only 4 bits (P4<3:0>) can be used. This port
address is located at 0D8H with the same function as that of port P1, except the P4.3 and P4.2 are
alternative function pins. It can be used as general I/O pins or external interrupt input sources (
INT3 ).
Example: P4REG0D8H
MOVP4, #0AH ; Output data "A" through P4.0−P4.3.
MOVA, P4; Read P4 status to Accumulator.
SETBP4.0; Set bit P4.0
CLRP4.1; Clear bit P4.1
Watchdog Timer
The Watchdog timer is a free-running timer which can be programmed by the user to serve as a
system monitor, a time-base generator or an event timer. It is basically a set of dividers that divide
the system clock. The divider output is selectable and determines the time-out interval. When the
time-out occurs a system reset can also be caused if it is enabled. The main use of the Watchdog
timer is as a system monitor. This is important in real-time control applications. In case of power
glitches or electro-magnetic interference, the processor may begin to execute errant code. If this is
left unchecked the entire system may crash. The watchdog time-out selection will result in different
time-out values depending on the clock speed. The Watchdog timer will de disabled on reset. In
general, software should restart the Watchdog timer to put it into a known state. The control bits that
support the Watchdog timer are discussed below.
INT2 /
Watchdog Timer Control Register
Bit:76543210
ENWCLRWWIDL--PS2PS1PS0
Mnemonic: WDTCAddress: 8FH
ENW : Enable watch-dog if set.
CLRW: Clear watch-dog timer and prescaler if set. This flag will be cleared automatically
WIDL : If this bit is set, watch-dog is enabled under IDLE mode. If cleared, watch-dog is disabled
under IDLE mode. Default is cleared.
PS2, PS1, PS0: Watch-dog prescaler timer select. Prescaler is selected when set PS2~0 as follows:
The time-out period is obtained using the following formula:
1
14
21000 12
OSC
Before Watchdog time-out occurs, the program must clear the 14-bit timer by writing 1 to WDTC.6
(CLRW). After 1 is written to this bit, the 14-bit timer , prescaler and this bit will be reset on the next
instruction cycle. The Watchdog timer is cleared on reset.
PRESCALER××× × mS
WIDL
IDLE
OSC1/12
Watchdog Timer Block Diagram
ENW
PRESCALER
CLRW
Typical Watchdog time-out period when OSC = 20 MHz
PS2 PS1 PS0WATCHDOG TIME-OUT PERIOD
0 0 019.66 mS
0 1 039.32 mS
0 0 178.64 mS
0 1 1157.28 mS
1 0 0314.57 mS
1 0 1629.14 mS
1 1 01.25 S
1 1 12.50 S
EXTERNAL
RESET
14-BIT TIMER
INTERNAL
RESET
CLEAR
Reduce EMI Emission
Because of the on-chip ROM, when a program is running in internal ROM space, the ALE will be
unused. The transition of ALE will cause noise, so it can be turned off to reduce the EMI emission if it
is not needed. Turning off the ALE signal transition only requires setting the bit 0 of the AUXR SFR,
which is located at 08Eh. When ALE is turned off, it will be reactivated when the program accesses
external ROM/RAM data or jumps to execute an external ROM code. The ALE signal will turn off
again after it has been completely accessed or the program returns to internal ROM code space.
AUXR - Auxiliary Register
Bit:76543210
- - --- --AO
Mnemonic: AUXRAddress: 8Eh
AO:Turn off ALE signal.
- 8 -
Preliminary W78C52D
ABSOLUTE MAXIMUM RATINGS
PARAMETERSYMBOLMIN.MAX.UNIT
DC Power Supply
V
CC−VSS
Input VoltageVINVSS -0.3VCC +0.3V
Operating TemperatureTA070
Storage TemperatureTST-55+150
Note: Exposure to conditions beyond those listed under Absolute Maximum Ratings may adversely affect the life and reliability of the
Operating CurrentIDD-20mAVDD = 5.5V, 20 MHz, no load
Idle CurrentIIDLE-6mAVDD = 5.5V, 20 MHz, no load
Power Down CurrentIPWDN-50
Input
Input Current
P1, P2, P3, P4
Input Leakage Current
EA
P0,
Input Current
RST
Logic 1-to-0 Transition Current
P1, P2, P3, P4
Input Low Voltage
RST
Input Low Voltage
P1, P2, P3, P4
Input Low Voltage
[*4]
XTAL1
IIN-50+10
ILK-10+10
IIN2-10+300
ITL-500-
VIL200.8VVDD = 4.5V
VIL100.8VVDD = 4.5V
VIL300.8VVDD = 4.5V
-0.3+7.0V
°C
°C
µA
µA
µA
µA
µA
VDD = 5.5V, no load
VDD = 5.5V
IN
= 0V or V
V
DD
VDD = 5.5V
V
SS < VIN < VDD
VDD = 5.5V
0 < V
IN < VDD
VDD = 5.5V
V
IN
= 2V
Publication Release Date: December 1998
- 9 -Revision A1
Preliminary W78C52D
DC Characteristics, continued
PARAMETERSYM. SPECIFICATIONTEST CONDITIONS
MIN.MAX.UNIT
Input
Input High Voltage
P1, P2, P3, P4
Input High Voltage
RST
Input High Voltage
XTAL1
[*4]
Output Low Voltage
P1, P2, P3, P4
Output Low Voltage
P0, ALE,
PSEN
[*4]
Sink Current
P1, P2, P3, P4
Sink Current
P0, ALE,
PSEN
Output High Voltage
P1, P2, P3, P4
Output High Voltage
P0, ALE,
PSEN
[*4]
Source Current
P1, P2, P3, P4
Source Current
P0, ALE,
Notes:
*1. RST pin has an internal pull-down.
*2. Pins of P1 and P3 can source a transition current when they are being externally driven from 1 to 0.
*3. RST is a Schmitt trigger input and XTAL1 is a CMOS input.
*4. P0, P2, ALE and
PSEN
are tested in the external access mode.
PSEN
VIH12.4VDD
VV
+0.2
VIH23.5VDD
VV
+0.2
VIH33.5VDD
VV
+0.2
Output
VOL1-0.45VVDD = 4.5V
VOL2-0.45VVDD = 4.5V
ISK148mAVDD = 4.5V
ISK2816mAVDD = 4.5V
VOH12.4-VVDD = 4.5V
VOH22.4-VVDD = 4.5V
ISR1-100-250
µA
ISR2-8-14mAVDD = 4.5V
DD = 5.5V
DD = 5.5V
DD = 5.5V
I
OL
= +2 mA
I
OL
= +4 mA
Vin = 0.45V
V
IN = 0.45V
OH
= -100 µA
I
OH
= -400 µA
I
VDD = 4.5V
V
IN = 2.4V
V
IN = 2.4V
- 10 -
Preliminary W78C52D
AC CHARACTERISTICS
The AC specifications are a function of the particular process used to manufacture the part, the
ratings of the I/O buffers, the capacitive load, and the internal routing capacitance. Most of the
specifications can be expressed in terms of multiple input clock periods (TCP), and actual parts will
usually experience less than a ±20 nS variation. The numbers below represent the performance
expected from a 0.5 micron CMOS process when using 2 and 4 mA output buffers.
Clock Input Waveform
XTAL1
T
CH
F
OP,
T
CL
T
CP
PARAMETERSYMBOLMIN.TYP.MAX.UNITNOTES
Operating SpeedFOP0-24MHz1
Clock PeriodTCP25--nS2
Clock HighTCH10--nS3
Clock LowTCL10--nS3
Notes:
1. The clock may be stopped indefinitely in either state.
2. The T
CP specification is used as a reference in other specifications.
3. There are no duty cycle requirements on the XTAL1 input.
Program Fetch Cycle
PARAMETERSYMBOLMIN.TYP.MAX.UNITNOTES
Address Valid to ALE LowTAAS
Address Hold from ALE LowTAAH
T
ALE Low to PSEN Low
PSEN Low to Data Valid
Data Hold after PSEN High
Data Float after PSEN High
APL
T
PDA--2 TCPnS2
T
PDH0 -1 TCPnS3
T
PDZ0 -1 TCPnS
ALE Pulse WidthTALW
T
PSEN Pulse Width
Notes:
1. P0.0−P0.7, P2.0−P2.7 remain stable throughout entire memory cycle.
2. Memory access time is 3 T
3. Data have been latched internally prior to
4. "∆" (due to buffer driving delay and wire loading) is 20 nS.
CP.
PSW
PSEN going high.
1 TCP-∆
1 TCP-∆
1 TCP-∆
2 TCP-∆
3 TCP-∆
--nS4
--nS1, 4
--nS4
CP -nS4
2 T
CP -nS4
3 T
Publication Release Date: December 1998
- 11 -Revision A1
Data Read Cycle
PARAMETERSYMBOLMIN.TYP.MAX.UNITNOTES
T
ALE Low to RD Low
RD Low to Data Valid
Data Hold from RD High
Data Float from RD High
RD Pulse Width
Notes:
1. Data memory access time is 8 T
2. "∆" (due to buffer driving delay and wire loading) is 20 nS.
CP.
DAR
T
DDA--4 TCPnS1
T
DDH0-2 TCPnS
T
DDZ0-2 TCPnS
T
DRD
Data Write Cycle
PARAMETERSYMBOLMIN.TYP.MAX.UNIT
T
T
T
T
DAW
DAD
DWD
DWR
ALE Low to WR Low
Data Valid to WR Low
Data Hold from WR High
WR Pulse Width
3 TCP-∆
6 TCP-∆
3 TCP-∆
1 TCP-∆
1 TCP-∆
6 TCP-∆
Preliminary W78C52D
-
3 TCP+∆
CP-nS2
6 T
-
3 TCP+∆
--nS
--nS
CP-nS
6 T
nS1, 2
nS
Note: "∆" (due to buffer driving delay and wire loading) is 20 nS.
Port Access Cycle
PARAMETERSYMBOLMIN.TYP.MAX.UNIT
Port Input Setup to ALE LowTPDS1 TCP--nS
Port Input Hold from ALE LowTPDH0--nS
Port Output to ALETPDA1 TCP--nS
Note: Ports are read during S5P2, and output data becomes available at the end of S6P2. The timing data are referenced to