Sir, Here is my UART program... $ org 000h ljmp begin org 23h ljmp serial_IT ;/** ; * FUNCTION_PURPOSE: This file set up uart in mode 1 (8 bits uart) with ; * timer 1 in mode 2 (8 bits auto reload timer). ; * FUNCTION_INPUTS: void ; * FUNCTION_OUTPUTS: void ; */ org 0100h begin: MOV SCON, #50h; /* uart in mode 1 (8 bit), REN=1 */ ORL TMOD, #20h; /* Timer 1 in mode 2 */ MOV TH1, #0FDh; /* 9600 Bds at 11.059MHz */ MOV TL1, #0FDh; /* 9600 Bds at 11.059MHz */ SETB ES; /* Enable serial interrupt*/ SETB EA; /* Enable global interrupt */ SETB TR1; /* Timer 1 run */ JMP $; /* endless */ ;/** ; * FUNCTION_PURPOSE: serial interrupt, echo received data. ; * FUNCTION_INPUTS: P3.0(RXD) serial input ; * FUNCTION_OUTPUTS: P3.1(TXD) serial output ; */ serial_IT: JNB RI,EMIT_IT ; test if it is a reception CLR RI ; clear reception flag for next reception MOV A,SBUF ; read data from uart MOV SBUF,A ; write same data to uart LJMP END_IT EMIT_IT: CLR TI ; clear transmition flag for next transmition END_IT: RETI end This program is taken from ATMEL SITe.. when i simulate it....during simulation how do i give serial input? When u just run it,setting RI manually...check out SBUF value...no value in it??? How to give serial input?? Since port 3 (P3.0 (RXD) and P3.1 (TXD) ) is used for serial communication.. how to set p3.1 as output pin and p3.0 as input pin?? Thank you. Tushar
"NOTE :: P3.0 and P3.1 are not connected to the serial port of computer. They are connected to RX and TX pins of RF transmitter/Receiver module." But in the Simulator they are not connected to anything at all - they don't even exist!! "Now when i give the input through serial window how do i come to know that it is coming from P3.0" Typing in the Serial Window simulates data arriving at P3.0 "Same is the case when i am transmitting...how do i come to know whether character that i am transmitting gets transmitted from P3.1?" It doesn't - it appears in the Serial Windows to simulate data being transmitted from P3.1!