EM78P451
OTP ROM
This specification is subject to change without prior notice.
2002/03/01
1
1. GENERAL DESCRIPTION
The EM78P451 is an 8-bit microprocessor designed and developed with low-power, high speed CMOS
technology. Its operational kernel is implemented with RISC-like architecture and is available in the mask
ROM version. The one time programmable (OTP) version is flexible, both in mass production or
engineering test stages. OTP provide users with unlimited volume with favorable price opportunities. This
device is equipped with the Serial Peripheral Interface (SPI) function and an easy-implemented RS-232.
The EM78P451 is very suitable for wired communication. Only 58 easy-to-learn instructions are needed
and user's program can be emulated with EMC In-Circuit Emulator (ICE).
EM78P451
OTP ROM
This specification is subject to change without prior notice.
2002/03/01
2
2. FEATURES
Operating voltage range: 2.3V~5.5V.
Operating temperature range: 0
C~70
C.
Operating frequency rang (base on 2 clocks ):
* Crystal mode: DC~20MHz at 5V, DC~8MHz at 3V, DC~4MHz at 2.3V.
* RC mode: DC~4MHz at 5V, DC~4MHz at 3V, DC~4MHz at 2.3V.
Low power consumption:
* Less then 3 mA at 5V/4MHz
* Typically 10
A during sleep mode
Serial Peripheral Interface (SPI) available.
4K
13 bits on chip ROM (EM78P451).
11 special function registers.
140
8 bits on chip general-purposed registers.
5 bi-directional I/O ports (35 I/O pins).
3 LED direct sinking pins with internal serial resistors.
Built-in RC oscillator with external serial resistor, 10% variation.
Built-in power-on reset.
5 stacks for subroutine nesting.
8-bit real time clock/counter (TCC) with overflow interrupt.
Two machine clocks or four machine clocks per instruction cycle.
Power down mode.
Programmable wake up from sleep circuit on I/O ports.
Programmable free running on-chip watchdog timer.
12 wake-up pins.
2 open-drain pins.
2 R-option pins.
32 programmable pull-high input pins.
Packages:
* 40 pin DIP 600mil
: EM78P451P.
* 44 pin QFP
: EM78P451AQ.
EM78P451
OTP ROM
This specification is subject to change without prior notice.
2002/03/01
3
Four types of interrupts.
* External interrupt (/INT).
* SPI transmission completed interrupt.
* TCC overflow interrupt.
* Timer1 comparator match interrupt.
EM78P451
OTP ROM
This specification is subject to change without prior notice.
2002/03/01
4
3. PIN ASSIGNMENT
2
3
4
5
6
7
8
9
1 0
1 1
1 2
1
1 3
1 4
1 5
1 6
1 7
1 8
1 9
2 0
3 9
3 8
3 7
3 6
3 5
3 4
3 3
3 2
3 1
3 0
2 9
4 0
2 8
2 7
2 6
2 5
2 4
2 3
2 2
2 1
V S S
I N T
D A T A
P 9 1
S D I / P 9 2
S D O / P 9 3
S C K / P 9 4
S S / P 9 5
C L K
P 9 0
O S C O
P 5 0
P 5 1
P 5 2
P 5 3
P 5 4
P 5 5
P 5 6
P 5 7
P 8 0
P 8 1
P 8 3
P 8 4
P 6 0
P 8 7
P 8 6
P 8 5
P 6 2
P 6 1
P 6 3
P 6 4
P 6 5
P 6 6
R - O S C I
V D D
P 7 1
P 7 2
P 6 7
P 8 2
EM78P451P/WM
P 7 0
1
2
3
4
5
6
7
8
9
1 0
1 1
12
13
14
15
16
17
18
19
20
21
22
44
43
42
41
40
39
38
37
36
35
34
P55
P56
P86
P85
P84
P83
P82
NC
P81
P80
P57
3 3
3 2
3 1
3 0
2 9
2 8
2 7
2 6
2 5
2 4
2 3
P 8 7
P 6 4
P 6 3
P 7 2
P 6 5
P 6 6
P 6 0
P 6 1
P 6 2
P 6 7
P 7 1
P 9 0
P 9 1
S D I / P 9 2
S D O / P 9 3
P 5 0
P 5 1
P 5 2
P 5 3
P 5 4
S C K / P 9 4
S S / P 9 5
DATA
CLK
VSS
OSCO
R-OSCI
VDD
NC
NC
NC
INT
E M 7 8 P 4 5 1 A Q
P70
Fig. 1 Pin Assignment
Table 1 Pin description
Symbol Pin No. Type
Function Description
R-OSCI
39
I
* In XTAL mode: Crystal input; In internal C, external R mode: 56Kohm
5%
pull high for 1.8432MHz.
OSCO
40
O * In XTAL mode: Crystal output; In RC mode: Instruction clock output.
P90~P95 5~10
I/O * General bi-directional I/O port. All of its pins can be pulled-high by software.
P90 and P91 are pin-change wake up pins.
P80~P87 19~26
I/O * General bi-directional I/O port. All of its pins can be pulled-high by software.
P80 and P81 are also used as the R-option pins.
P70~P72 37~35
I/O * LED direct-driving pin with internal serial resistor used as output and is
software defined.
CLK
4
I/O
* By connecting P74 and P76 together.
* P74 can be pulled-high by software and it is also a pin-change wake up pin.
* P76 can be defined as an open-drain output.
DATA
3
I/O
* By connecting P75 and P77 together.
* P75 can be pulled-high by software and it is also a pin-change wake up pin.
* P77 can be defined as an open-drain output.
P60~P67 27~34
I/O * General bi-directional port. All of its pins can be pulled-high by software, and
pin-change wake up pins.
P50~P57 11~18
I/O * General bi-directional I/O port. All of its pins can be pulled-high individually
by software.
VDD
38
-
* Power supply pin.
VSS
1
-
* Ground pin.
/INT
2
I
* An interrupt schmitt-triggered pin.
EM78P451
OTP ROM
This specification is subject to change without prior notice.
2002/03/01
5
* The function of interrupt triggers at the falling edge.
* Users can enable it by software. The internal pull-up resistor is around 50K
ohms.
SDI
7
I/O * Serial data in for SPI
SDO
8
I/O * Serial data out for SPI.
SCK
9
I/O * Serial clock for SPI.
/SS
10
I/O * /Slave select for SPI.
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