In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Jean Brunet wrote:

Peter,

Your mail is very interressant.

Y am appy that it'is possible to transmit two frames (a start bit, 8 bits of data, and a stop bit, I confirm ) in a little space of time.
1/38400 = .000026041. Yes, of course ! Also the pulse is 1/4 of 26 us = 6.5 us. My interrupt code is a 1 us int period. 7 us is also good.

Look my interrupt code, with two timer :

		sb	tf_square	           ; if set 
		jmp	:st
		inc	Sq_freq	          ; time square pulse 26 us
		snz
		jmp	:tf_end               ; finish
		sb	Ir_set                    ; if set 
		jmp	:no	
		setb	IrPin                     ; bit Tx  Irda
		inc	Freq_Tir		;  time pulse  7 us
		sz
		jmp	:st                       ; end of pulse
:no		clrb	IrPin                   ; pulse 7 us terminate
		clrb	Ir_set                 ; flag end of pulse		
		mov	Freq_Tir,#Freq_BitIr                ; time pulse
		jmp	:st
:tf_end		clrb	tf_square                               ; end of square pulse
		mov	Sq_freq,#Freq_SqIr	            ; time square pulse	
:st		

The same code permit a bit set or a bit clear if Ir_set  flag is true or false.

In a main code

Ir_NoModulate
	clrb    Ir_set		; signal off / or On if Ir_set is set.
	setb	tf_square	; 
:I2	snb	tf_square	; when interrupt code is finish....
	jmp	:I2
	ret
And the trame :

trame
	call	Ir_Modulate	; start bit
	mov	idx,#8
:t0	sb	temp0.0
	jmp	:no
	call	Ir_NoModulate	; if  bit set, no  modulation
	skip
:no	call	Ir_Modulate
	clc
	rr	temp0
	decsz	idx
	jmp	:t0
	clc
                call	Ir_NoModulate     ' stop bit
                ret

Thank's
Jean

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