EM78P451S
8-Bit Microcontroller with OTP ROM
Table 1 Pin description
Symbol Pin No. Type
Function Description
ꢀ In XTAL mode: Crystal input; In internal C, external R mode: 56Kohm±5% pull
39
40
I
R-OSCI
OSCO
high for 1.8432MHz.
O
ꢀ In XTAL mode: Crystal output; In RC mode: Instruction clock output.
ꢀ 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.
5~10
I/O
P90~P95
ꢀ 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.
ꢀ LED direct-driving pin with internal serial resistor used as output and is
software defined.
19~26
37~35
I/O
I/O
P80~P87
P70~P72
ꢀ LED direct-driving pin with internal serial resistor used as output and is
software defined.
ꢀ Code option bit 3 (REN): reset enable
P70/
RESET
37
I/O
REN=0 => for reset pin
REN=1 => for general purpose I/O (P70)
Internal pull high resistor 220Kohm
ꢀ By connecting P74 and P76 together.
4
3
I/O
I/O
CLK
ꢀ 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.
ꢀ 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.
ꢀ General bi-directional port. All of its pins can be pulled-high by software, and
pin-change wake up pins.
DATA
27~34
11~18
I/O
I/O
P60~P67
ꢀ General bi-directional I/O port. All of its pins can be pulled-high individually by
software.
P50~P57
VDD
38
1
-
-
ꢀ Power supply pin.
ꢀ Ground pin.
VSS
ꢀ An interrupt schmitt-triggered pin.
2
I
/INT
ꢀ The function of interrupt triggers at the falling edge.
ꢀ Users can enable it by software.
7
8
I/O
I/O
I/O
I/O
SDI
SDO
SCK
/SS
ꢀ Serial data in for SPI
ꢀ Serial data out for SPI.
ꢀ Serial clock for SPI.
ꢀ /Slave select for SPI.
9
10
Product Specification (V1.0) 06.01.2004
• 3
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
