Hi All.

I´m writing a code that increments a variable by 1 each time the pin 3.0 goes from 1 to 0. The I put the count on P1.

The program works ok on the simmulator, but once I load it to my evaluation board, I only got 01H on P1.

I just put directly to ground the p3.0 in order to simulate the 0.

My question is: do I need external circuits to test this?? do I need a '373 latch??

I'm using an AT89c1

Here is my code:

CNT EQU 70H
EA EQU 69H
EP EQU 68H


ORG 0000H
JMP INICIO

ORG 0030H
INICIO: MOV EA,#01H
MOV EP,#01H
MOV CNT,#00H
MOV P3,#01H
MOV P1,#01H
CICLO: MOV A,P3
JNZ UNO

MOV EA,#0H
MOV A,EP
CJNE A,EA,CAMBIO
MOV EP,#00H
JMP CICLO

CAMBIO: MOV EP,#0H
INC CNT
MOV P1,CNT
JMP CICLO



CERO: NOP

UNO MOV EA,#01
MOV A,EP
CJNE A,EA,PASO
MOV EP,#01H
JMP CICLO
PASO: MOV EP,#01
JMP CICLO



END

Yhanks for your help!!! :)