uart.asm

8051 ASM source code for MLX90614 tempture sensor

							SUBTITLE "Software uart subroutines"

#define TX_	   GPIO,2

;************************************************************************************************************
;							 		SEND BYTE BY UART	
;************************************************************************************************
;Name:		pic10_uart 
;Function:	Send a byte by uart
;Input:		W
;Output:	No
;Comments:  
;************************************************************************************************************
pic10_uart
    MOVWF	TX_buffer				; Load the sent byte in a data register
    CALL	start_bit				; Generate START bit
    CALL	send_byte          		; Send byte
    CALL	stop_bit				; Generate STOP bit
    RETLW	0
;----------------------------------------------------------------------------------------------
stop_bit
    BCF		TX_						; Clear TX_ line

	MOVLW	BAUDRATE				;|
	MOVWF	counterL				;|
    DECFSZ	counterL,f				; > Define a single bit duration
    GOTO	$-1						;|	
   	NOP								;|
	  									
    RETLW	0
;----------------------------------------------------------------------------------------------
start_bit
    BSF		TX_						; Set TX_ line
    
    MOVLW	BAUDRATE				;|
	MOVWF	counterL				;|
    DECFSZ	counterL,f				; > Define a single bit duration
    GOTO	$-1						;|	
   	NOP								;|
   	  	
    RETLW	0
;----------------------------------------------------------------------------------------------
send_byte
  	MOVLW	D'8'					; 8 -> W
  	MOVWF	Bit_counter				; W -> Bit_counter
send_next_bit
  	RRF		TX_buffer,F				; Shift TX_buffer to right
  	BTFSS	STATUS,C				; Check STATUS<C> 
  	GOTO	send_1					; If C=1 send 1 by the uart
  	GOTO	send_0					; Else send 0 by the uart

send_1
  	BSF		TX_						; Set TX_ line
  	
  	MOVLW	BAUDRATE				;|
	MOVWF	counterL				;|
    DECFSZ	counterL,f				; > Define a single bit duration
    GOTO	$-1						;|	
   	NOP								;|
   	
  	GOTO	end_send_byte
  	
send_0
  	BCF		TX_						; Clear TX_ line
  	
  	MOVLW	BAUDRATE				;|
	MOVWF	counterL				;|
    DECFSZ	counterL,f				; > Define a single bit duration
    GOTO	$-1						;|	
   	NOP								;|
    		
end_send_byte  
  	DECFSZ	Bit_counter,F			; All bits are sent?
  	GOTO	send_next_bit			; No,send next bit
  	RETLW	0

;----------------------------------------------------------------------------------------------