Hi. I made my first RS232 hardware... Simple... 89C51 connected to MAX232.

I downloaded the following code from 8052.com :


MOV SCON,#01110000B
MOV TH1,#0FDH
MOV TCON,#01010101B
MOV TMOD,#00100001B

START: JNB RI,START
CLR RI
MOV A,SBUF
MOV SBUF,A
SJMP START

It worked well. You push some key on your PC Keyboard goes to your uC and back to your PC to show the key in the monitor.

Then I said... Ok... I'll make a VERY BIG change:


MOV SCON,#01110000B
MOV TH1,#0FDH
MOV TCON,#01010101B
MOV TMOD,#00100001B

mov R0, #65h

START: JNB RI,START
CLR RI
MOV A, R0 ;SBUF
MOV SBUF,A
ACALL delay

SJMP START

delay:
djnz R0, delay
djnz R0, delay
ret


Now it's not working.... :(

The only thing I want to do is send what I have in R0 (or other registers) to my PC and show it on the sceen.... Only that... But with those lines I added now it's not working...

How should I send a Register content to SBUF?

Can you help me?

Thank you.