Cirrus-logic AN118 Manual do Utilizador descarregar pdf (Página 30)

AN118

30 AN118REV2

;****************************************************************

;* Routine - TXSER

;* Input - Byte to be transmitted is placed in R7

;* Output - None

;* Description - This subroutine transfers 1 byte from converter

;* via UART. It uses the RS-232 serial protocol to transmit

;* one byte from a 80C51 to the PC/UART system. To

;* function properly, the programmer must first initialize the

;* TI bit in the SCON register to 0X01.

;****************************************************************

;The function prototype is: void TXSER(char);

$DEBUG

USING 0 ; Use register bank 0

TCOD SEGMENT CODE ; Define TCOD as a segment of code

PUBLIC _TXSER ; Make subroutine global

RSEG TCOD ; Make code relocatable

_TXSER: JNB SCON.1,$ ; Poll TI

CLR SCON.1 ; Reset TI

MOV SBUF, R7 ; Move byte to output register

RET ; Exit subroutine

END

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Cirrus-logic AN118 Manual do Utilizador Página 30