Problem receiving data from PC using the MAX 232

[arun]

Hi,

I am using a MAX 232 IC for RS 232 communications. I am having problem receiving data from the PC , but I am having no trouble sending data to the PC.

I used a oscilloscope to check the pulses and I noticed that I get pulses on the MAX pin 8 when pin_c7 of 16F877 is not connected to the MAX.

The MAX 232 IC is connected using the standard techniques . the code is given below.


#include <16F877.h>

#FUSES XT,NOWDT,NOBROWNOUT, NOLVP, NOWRT

#use delay(clock=4000000)
#use standard_io(C)
#use rs232(baud=9600,xmit=pin_c6, rcv=pin_c7,parity=n)

enum enmType {TXDONLY,RXDONLY,TXDRXD};

int nType,bHigh;


void init()
{
setup_adc_ports(no_analogs);
setup_adc(adc_off);

set_tris_a(0xFF);
set_tris_b(0xFF);
set_tris_d(0xC0);
//set_tris_c(0xAF);

output_float(pin_c7);
nType=TXDONLY;

set_timer2(0);
setup_timer_2(T2_DIV_BY_1,0xFF,1);

}

void main()
{

init();

do
{

switch (nType)
{
case TXDONLY:

putc('A');
break;

case RXDONLY:

bHigh=0;
break;


case TXDRXD:

putc( getc()+1 );
break;
}


} while(TRUE);


}

[ckielstra]

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