communication between 16F877 and 16F84

[HU]

Hiii... everybody

I am in trouble...
PLS HELP ME...
I am about to get crazy !

I have two PICs. One is PIC16F877. The other one is PIC16F84.
I am trying to use RS232 communication between to PICs.

16F84 is driving a LCD module thru PortB of 16F84
Both 16F877 and 16F84 are powered from the same power supply.

A 30K resistor is connected to the transmitting bus line as pull-up resistor.
Usually, They are communicating without any problem.

But for some startup times, (by applying the power supply) , Nothing can be seen on LCD (except some untidy lines) And LCD stays like that.

For trouble shooting, I connected the transmitter (16F877) to PC ( using hyper terminal), there was no problem. What was sent could be printed on screen.

When I connect PC to my receiver PIC (16F84) , I rarely meet a problem.
If circuits start correctly, No problems and they are working fine. After that, Whenever anyone (or both) of PICs are reset, There is no trouble as well.
Reset order of PICs does not change any thing. Communication is going on perfectly.

Why is the communication becoming bad for some startups?

What should I do?

Unfortunately, It is urgent...

Best wishes


Here is my code for 16F877:

#include <16F877.h>
#device *=16 ADC=10
#fuses XT, NOWDT, NOPROTECT, NOBROWNOUT
#use delay(clock=4000000)
#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8,errors)


void main() {

unsigned int i=0;

setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_CLOCK_DIV_2);
setup_spi(FALSE);
setup_psp(PSP_DISABLED);
setup_counters(RTCC_INTERNAL,RTCC_DIV_2);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_ccp1(CCP_OFF);
setup_ccp2(CCP_OFF);

while(1){

delay_ms(500);
printf("%d", ++i);
putchar(13);
putchar(10);


}

}

The following is code for 16F84 :

#include<16c84.h>
#include<stdio.h>
#fuses XT,NOPROTECT,NOWDT
#use delay(clock=4000000)
#use rs232(baud=9600, rcv=PIN_A1,xmit=PIN_A0,parity=n,bits=8,invert)
//
// the following file is included with the examples that come
// with CCS. You should modify it for your type of LCD before you
// use it!

#include"lcd.c"

//
// declare the rs232 parameters. Leave off the INVERT if you are feeding
// this from a PC through a MAX232 or similar
//



main() {

//
// If you feed the buffer with more than 16 characters, it will crash
// So you might want to bullet proof this a whole lot more. I didn't
// and my prototypes work fine - because I don't send it more than
// 16 characters (grin). PS: the extra characters in the array are for
// the carriage return/null on the end of the string.
//
// The array initialization is not needed, but shown as a reminder of
// the space being used.
//
char buf[18]={32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32,32};
unsigned xc=0;
lcd_init();

lcd_putc("\fReady . . .\n");
delay_ms(2000);
lcd_putc("\f");
while(1)
{
gets(buf); // puts data into buf[] until it reaches a char 13 (cr)
lcd_putc("\f"); // clears screen before printing buffer - remove if more
// than one line LCD. Clear it with your input code instead.

for(xc=0;xc<16;xc++)
{
if(buf[xc]==0) buf[xc]=32; // eliminate the null character
if(buf[xc]==13) buf[xc]=32; // not needed if using gets to get string
if(buf[xc]==10) buf[xc]=32; // not needed if using more than 1X16
lcd_putc(buf[xc]); //
buf[xc]=32; // resets buffer contents to spaces
}
}
}

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