Maker Pro
Maker Pro

UART problem for PIC microcontroller

saur

Sep 28, 2010
8
Joined
Sep 28, 2010
Messages
8
I am using pic24fj64ga002 controller UART. I am able to communicate with PC when I transmit/receive one character to PC. But my intention is to get a string from PC and process it in microcontroller. However, I am getting a weird problem. When I am sending more than 5 characters, eg. abcdefg, I am able to store 'ab' but I get some special character out of cdefg might be like $ or (.
similarly if i enter "i am a microcontroller", i am able to store "i am a microcontr" followed by some special character.
If the number of characters is less than 5, eg abcd, i am getting a special character or null value.



#include <p24FJ64GA002.h>
#define FCY 16000000UL // instruction cycle rate (ignore)
#include <libpic30.h> // __delay32
// __delay_ms and __delay_us
// note: use only small values
#include <stdio.h>
#define USE_AND_OR // enable AND_OR mask setting
#include <string.h>

#define BAUD_19200 51 // brg for low-speed, 32 MHz clock
#define TotalCharacters 50 //total number of characters to be entered
//-----------------------------------------------------------------------------
// Subroutines
//-----------------------------------------------------------------------------

// Initialize Hardware
void init_hw()
{
LATBbits.LATB3 = 0; // write 0 into output latches
LATBbits.LATB5 = 0;
TRISBbits.TRISB3 = 0; // make green led pin an output
TRISBbits.TRISB5 = 0; // make red led pin an output
AD1PCFGbits.PCFG9 = 1; // make push button a digital input
CNPU1bits.CN11PUE = 1; // enable pull-up for push button
RPINR18bits.U1RXR = 11; // assign U1RX to RP11
RPOR5bits.RP10R = 3; // assign U1TX to RP10
}

void serial_init(int baud_rate)
{
// set baud rate
U1BRG = baud_rate;
// enable uarts, 8N1, low speed brg
U1MODE = 0x8000;
// enable tx and rx
U1STA = 0x0400;
}

void serial_puts(char str[])
{
int i;
for (i = 0; i < strlen(str); i++)
{
// make sure buffer is empty
while(U1STAbits.UTXBF);
// write character
U1TXREG = str;
}
}

char serial_getc()
{
// clear out any overflow error condition
if (U1STAbits.OERR == 1)
U1STAbits.OERR = 0;
// wait until character is ready
while(!U1STAbits.URXDA);
return U1RXREG;
}

// Wait for PB Press
void wait_pb()
{
while (PORTBbits.RB15 == 1); // wait until pb pressed
}

//-----------------------------------------------------------------------------
// Main
//-----------------------------------------------------------------------------

int c;
char gReceivedData,gReceivedString4mPC[TotalCharacters];


int gParameterTypes[10][5];
int main(void)
{

init_hw(); // initialize hardware
serial_init(BAUD_19200); // configure uart
//step 1
LATBbits.LATB3 = 1; // blink green LED for 500ms
__delay32(8000000);
LATBbits.LATB3 = 0;
/*
wait_pb(); // wait for pb press
*/
serial_puts("Enter command "); // print greeting


//step 2
checkReceivedDataForCRnBS();
//step 2.5
// testStorageOf1DArray();


//flush global variables
flushGlobalVariables();


return 0;
}
/*
This function gets characters entered by user using PC and reads it in microcontroller. Then, it checks for carrage return,backspace, and a valid character. It forms
a string and stores it in global variable gReceivedString4mPC.

*/
void checkReceivedDataForCRnBS(){

//step 2 start
int lCounterNumberOfCharactersReceived = 0;
//receiving character from UART
while(1){
gReceivedData = serial_getc();
if(gReceivedData == 13){ break; }
//checking for backspace
if(gReceivedData == 8 ){
if(lCounterNumberOfCharactersReceived>0){
lCounterNumberOfCharactersReceived--;
}
}else{
//if character is greater than or equal to ''(ascii 32) then, its alphabet or number or
// special character such as space , comma, colon. Store it in array.
if(gReceivedData >=32){
gReceivedString4mPC[lCounterNumberOfCharactersReceived] = gReceivedData;
//serial_puts(gReceivedString4mPC[lCounterNumberOfCharactersReceived]);
lCounterNumberOfCharactersReceived++;
}

}

}
// if it is carrage return, add a null terminator
gReceivedString4mPC[lCounterNumberOfCharactersReceived] = 0;


}
 
Top