Hi,

I think the solution for 8051 as presented by Ungureanu Silviu can be modified to make it fully featured one.


He proposed:

JNB P3.2,$ ;Wait Till INT0 Goes High
JB P3.2,$ ;Wait Till INT0 Goes Low
RETI ;Go Back and Execute One Instruction

I would modify this to:


======================
ORG 0003H ; INT 0 VECTOR

CLR TR0 ; Stop all timers
CLR TR1

CALL DATA_OUT ;Send Data to PC for debug

JNB P3.2,$ ; Wait for step
JB P3.2,$

SETB TR0 ; RE START ALL TIMERS
SETB TR1

RETI
===========================

You will have to save timer 0 by pushing to allow serial communication and restart and pop at the end of transmission but stopping it before reloading its values.

Simon

PS: The vector address and timer 0 or 1 for serial communication I am not sure. Please correct it.