dear all,
m trying to make a project on interfacing rs232 with pic18f4550. m new to rs232 .cananybody please help me with some examples based on rs232 communication with pic18f.

 

Here's some code I wrote when I was learning to do RS232 on the 18F1320. It's just simple polled RS232. I have some 4550 code, but I don't know if it works. This 1320 code definitely does.

__________________
=========================
Futz's Microcontrollers & Robotics
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Hi

I would recommend these projects:

http://www.sixca.com/eng/articles/usbdaq/index.html
http://www.embedds.com/simple-usb-to...on-pic18f2455/
http://www.piccoder.co.uk/content/view/42/26/http://www.piccoder.co.uk/content/view/42/26/

Good luck,

Ferenc

 

Dear frnds

this code i tried out for usart with pic18f4550 but m geeting the error which i have decribed below ..please help out.m using mplabc18 compiler



#include <p18f4550.h>

#include <usart.h>

void rx_handler (void);
#define BUF_SIZE 25

#pragma idata bigdata
char data[11][BUF_SIZE+1] = {
{ "String #0\n\r" },
{ "String #1\n\r" },
{ "String #2\n\r" },
{ "String #3\n\r" },
{ "String #4\n\r" },
{ "String #5\n\r" },
{ "String #6\n\r" },
{ "String #7\n\r" },
{ "String #8\n\r" },
{ "String #9\n\r" },
{ "Invalid key (0-9 only)\n\r" }
};
#pragma idata
#pragma code rx_interrupt = 0x8
void rx_int (void)
{
_asm goto rx_handler _endasm
}
#pragma code
#pragma interrupt rx_handler
void rx_handler (void)
{
unsigned char c;
/* Get the character received from the USART */
c = ReadUSART();
if (c >= '0' && c <= '9')
{
c -= '0'; /* Display value received on LEDs */
PORTB = c;

putsUSART (data[c]);
}
else
{

putsUSART (data[10]); /* Display value received on LEDs */
PORTB = c;
}
/* Clear the interrupt flag */
PIR1bits.RCIF = 0;
}
void main (void)
{
/* Configure all PORTB pins for output */
TRISB = 0;

OpenUSART (USART_TX_INT_OFF &
USART_RX_INT_ON &
USART_ASYNCH_MODE &
USART_EIGHT_BIT &
USART_CONT_RX &
USART_BRGH_HIGH, 103);

putrsUSART (
(const far rom char *)"\n\rEnter a digit 0-9!\n\r");

RCONbits.IPEN = 1;

IPR1bits.RCIP = 1;

INTCONbits.GIEH = 1;

while (1)
;
}

the linker file added is


// File: 18f4550.lkr
// Sample linker script for the PIC18F4550 processor

LIBPATH .

FILES c018i.o
FILES clib.lib
FILES p18f4550.lib

CODEPAGE NAME=vectors START=0x0 END=0x29 PROTECTED
CODEPAGE NAME=page START=0x2A END=0x7FFF
CODEPAGE NAME=idlocs START=0x200000 END=0x200007 PROTECTED
CODEPAGE NAME=config START=0x300000 END=0x30000D PROTECTED
CODEPAGE NAME=devid START=0x3FFFFE END=0x3FFFFF PROTECTED
CODEPAGE NAME=eedata START=0xF00000 END=0xF000FF PROTECTED

ACCESSBANK NAME=accessram START=0x0 END=0x5F
DATABANK NAME=gpr0 START=0x60 END=0xFF
DATABANK NAME=gpr1 START=0x100 END=0x1FF
DATABANK NAME=gpr2 START=0x200 END=0x2FF
DATABANK NAME=gpr3 START=0x300 END=0x3FF
DATABANK NAME=usb4 START=0x400 END=0x4FF PROTECTED
DATABANK NAME=usb5 START=0x500 END=0x5FF PROTECTED
DATABANK NAME=usb6 START=0x600 END=0x6FF PROTECTED
DATABANK NAME=usb7 START=0x700 END=0x7FF PROTECTED
ACCESSBANK NAME=accesssfr START=0xF60 END=0xFFF PROTECTED

SECTION NAME=CONFIG ROM=config

STACK SIZE=0x100 RAM=gpr3




error which m getting while complilation is

Error - section 'bigdata' can not fit the section. Section 'bigdata' length=0x0000011e
Errors : 1

 

Getting back to basics, if you need to hook the 4550 up to a PC make sure you are using a level shifter such as a MAX232 or similar.