bad communication between pic and pc

[Milo]

Hey all, ... I am having a problem when connecting pic to pc. I can print messages to pc using printf statements, ... However, when it comes to putting characters from pc to pic, the whole thing crashes. Seems like whenever i try to use
getc(), everything goes down the drain. Here is a program I am trying to test, ... As you can see, program should work only when it receives lowercase l from pc, ... However, it works with any key pressed, ... Sometimes it even crashes and generates garbage, ... Most of the times it doesn't work at all, ... I am not using MAX232, therefore I used INVERT option in my #use rs232 directive, ... Also, my clock is external 20 MHz, ... The wave looks more like a sinusiod than square, ... Could this be a problem?, ... Anyway, here is the code, and if you have any sugggestions, help is always welcome, ...

#include <16F84A.h>
#use delay(clock=20000000)
#fuses HS,NOWDT
#use rs232(baud=9600,parity=N,xmit=PIN_B1,rcv=PIN_B2, INVERT)


void main()
{
byte answer;

//setup_counters(RTCC_EXT_L_TO_H,RTCC_DIV_2);


#use standard_io(A)
SET_TRIS_A(0x00); //ALL A PINS AS OUTPUTS
OUTPUT_LOW(pin_A0);
OUTPUT_LOW(pin_A1);
OUTPUT_LOW(pin_A2);
OUTPUT_LOW(pin_A3);


#use standard_io(B)
SET_TRIS_B(0x04); //B2 INPUT; B1 OUTPUT;

OUTPUT_B(pin_B1);

OUTPUT_LOW(pin_B0);
OUTPUT_LOW(pin_B3);
OUTPUT_LOW(pin_B4);
OUTPUT_LOW(pin_B5);
OUTPUT_LOW(pin_B6);
OUTPUT_LOW(pin_B7);


disable_interrupts(GLOBAL);
disable_interrupts(INT_RTCC);
disable_interrupts(INT_RB);
disable_interrupts(INT_EEPROM);
disable_interrupts(INT_EXT);

putc(13); //this is where the problem occurs
delay_ms(85);

do{
answer=getch();
}while (answer!=0x6c);



printf("Emergency!... Emergency!... Emergency!... \n");
putc(13);
}
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515188

[PCM programmer]

Do you have a 10K resistor on Pin B2 ? If you're not using
a MAX232 chip, then you need the resistor.

:=#include <16F84A.h>
:=#use delay(clock=20000000)
:=#fuses HS,NOWDT
:=#use rs232(baud=9600,parity=N,xmit=PIN_B1,rcv=PIN_B2, INVERT)
:=
:=
:=void main()
:={
:= byte answer;
:=
:= //setup_counters(RTCC_EXT_L_TO_H,RTCC_DIV_2);
:=
:=
Standard I/O is the default. You don't have to specify it,
unless you're switching to fast_io at some other point
in the program.

:= #use standard_io(A)
:= SET_TRIS_A(0x00); //ALL A PINS AS OUTPUTS
:= OUTPUT_LOW(pin_A0);
:= OUTPUT_LOW(pin_A1);
:= OUTPUT_LOW(pin_A2);
:= OUTPUT_LOW(pin_A3);
:=
:=
:= #use standard_io(B)
:= SET_TRIS_B(0x04); //B2 INPUT; B1 OUTPUT;
:=

This next line is not correct. You're writing the value
for "pin_B1", which is 49 (0x31) to Port B. I doubt that
this is what you intended to do.
:= OUTPUT_B(pin_B1);
:=
:= OUTPUT_LOW(pin_B0);
:= OUTPUT_LOW(pin_B3);
:= OUTPUT_LOW(pin_B4);
:= OUTPUT_LOW(pin_B5);
:= OUTPUT_LOW(pin_B6);
:= OUTPUT_LOW(pin_B7);
:=
:=
These interrupts are disabled upon power-up.
You don't need to turn them off.
:= disable_interrupts(GLOBAL);
:= disable_interrupts(INT_RTCC);
:= disable_interrupts(INT_RB);
:= disable_interrupts(INT_EEPROM);
:= disable_interrupts(INT_EXT);
:=
:= putc(13); //this is where the problem occurs
:= delay_ms(85);
:=
:= do{
:= answer=getch();
:= }while (answer!=0x6c);
:=
:=
:=
:= printf("Emergency!... Emergency!... Emergency!... \n");
:= putc(13);

The PIC will go to sleep right here. Do you want that ?
If not, put this statement here:
while(1);

:=}
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515191

[Milo]

Thanx a lot man, ... The program works perfectly now, ... Milo
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515192