rs232 soft uart

[lgeorge123]

here I have my program using 16f877 to receive data from pc,once i
write down a ASCII B,a ASCII U is return, I tries many times but unsuccessfully.
in the main loop,one point is be minded that no while(1) should be used.
#include <16f877.H>
#fuses HS,NOWDT,NOPROTECT,NOLVP,BROWNOUT
#use delay(clock=12000000)
#use rs232(baud=9600, xmit=PIN_A5, rcv=PIN_A4,FORCE_SW,errors)
#byte porta = 5
#byte portb = 6
#byte portc = 7
#byte portd = 8
#byte porte = 9

char byte_read;

#int_rda
serial_isr(){

byte_read=getc();}
void main()
{
enable_interrupts(global);
enable_interrupts(int_rda);
setup_adc(no_analogs);
set_tris_a(0x00);
set_tris_b(0x00);
set_tris_c(0x00);
set_tris_d(0x00);
set_tris_e(0x00);

porta=0;
portb=0;
portc=0;
portd=0;
porte=0;



if (byte_read=='B')
{
putc('U');
byte_read=0;
}


}

[SherpaDoug]

I don't think the software UART can use interrupts. Try stripping out the interupt stuff and just write a program the blinks a LED when it receives any serial character. Then make it blink when it receives a 'B'. Then write one that sends 'U'. Then one that sends 'U' when it receives 'B'.
For interrupts you need to use the hardware UART.
_________________
The search for better is endless. Instead simply find very good and get the job done.

[rwyoung]

It is possible to make a soft UART using interrupts if you use the interrupt on change/edge of RB0. But only for receiving. The "start" bit transition triggers the interrupt. Never tried it myself but I do remember reading about it here.

You can find more information using the forum's "search" feature.
_________________
Rob Young
The Screw-Up Fairy may just visit you but he has crashed on my couch for the last month!

[ckielstra]

[lgeorge123]

actually I have a function,inside it a getchar() function is working,so it is
waiting user to input the data via visual basic program.could somebody give me any suggestion????????
#include <16f877.H>
#fuses HS,NOWDT,NOPROTECT,NOLVP,BROWNOUT
#use delay(clock=12000000)
#use rs232(baud=9600, xmit=PIN_A5, rcv=PIN_A4,force_sw,errors)
#byte porta = 5
#byte portb = 6
#byte portc = 7
#byte portd = 8
#byte porte = 9
int erase();
int program_chip();
char data_read;
int pass,pass1;
//portb=data,portc=a0-a7,portd=a8-a15,porte=a16-a18
//********************************************************************
void main()
{ setup_adc(no_analogs);
set_tris_a(0b0010000);
set_tris_b(0);
set_tris_c(0);
set_tris_d(0);
set_tris_e(0);
porta=0;
portb=0;
portc=0;
portd=0;
porte=0;
pass=0;
pass1=0;

pass= erase();
while(1){
if ((pass==1)||(pass1==1))
{ porta=0x06;
pass1=program_chip();
if (pass1==1)
porta=0x05; //pass

else
porta=0x07; //fail
}
else

porta=0x07;}
}//main
int program_chip()
{ char byte_read,byte_read1;
long index1,index2,index3;

index1=0;
index2=0;
index3=0;
pass1=0;
byte_read=0;

for(index1=0;index1<=0xff;index1++)
for(index2=0;index2<=0xff;index2++)
for(index3=0;index3<=0x07;index3++)
{

porta=0x01;
portc=index1;
portd=index2;
porte=index3;
byte_read=getchar(); //this is the place to waiting for data
if(byte_read!='!'){
set_tris_b(0x00);
portb=byte_read;
putc('M');
delay_us(100);
porta=0x02;
;;;;
;;;;;;