Hey guys, I've been trying to get two 8051 connected to each other via the serial port, but I'm getting nowhere.

First, let me clarify my hardware connections. I need to send the letter 'A' from the first 8051 (lets call it 8051-X) to the second 8051 (8051-Y). Both controllers are using a 22.1184MHz crystal. I connected the TXD pin (pin 11) of 8051-X directly to the RXD pin (pin 10) of 8051-Y.

Now the codes. On 8051-X, I have the following:

	ORG	0000H
	CLR	P1.4
	CLR	P1.5

	MOV	SCON, #01010000B
	MOV	TMOD, #21h
	
	MOV	TH1, #high(232)
	SETB	TR1

WAIT:	CLR	TI
	JNB	P1.5, $ ;this thing is just so that I send one 'A' at a time
	JNB	P1.4, $
	MOV	SBUF, #'A'
	JNB	TI, $
	CLR	P1.5
	CLR	P1.4
	JMP	WAIT

	END
 

On 8051-Y, I have this:

	ORG	0000H
	CLR	P3.7

	MOV	SCON, #01010000B
	MOV	TMOD, #21h
	
	MOV	TH1, #high(232)
	SETB	TR1

WAIT:	JNB	RI, $
	MOV	A, SBUF
	SUBB	A, #'A'
	JNZ	WAIT
	SETB	P3.7  ;this is connected to a transistor and an LED

	END
 

Using an oscilloscope, I can see that the TTL version of the letter A reaches the RXD pin (pin 10) of 8051-Y. But the code never seems to go to the SETB 3.7 line as the LED never lights up.

I would really appreciate some help here. Thanks!

*ps: the transistor-LED combo works when I manually do SETB 3.7.