[SOLVED] PIC18F4520 UART interfacing using C18

Code C - [expand]
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#include "p18f4520.h"
#include "usart.h"
 
/*------------------------------------------------------------
            SETTING MICROCONTROLLER CONFIGURATION BITS
------------------------------------------------------------*/
#pragma config OSC = HS
#pragma config WDT = OFF
#pragma config LVP =OFF
 
/*------------------------------------------------------------
                    DEFINE Rx and Tx PORTS
-------------------------------------------------------------*/
#define Tx_port                     TRISCbits.TRISC6
#define Rx_port                     TRISCbits.TRISC7
 
/*------------------------------------------------------------
         DEFINE USART STATUS AND CONTROL REGISTER BITS
-------------------------------------------------------------*/
#define Serial_port_enable                  RCSTAbits.SPEN //serial port enable or disable bit in RCSTA register
#define Transmission_mode                   TXSTAbits.SYNC //transmission mode selection bit (synchronous or Asynchronous) in TXSTA register
#define Tx_enable                           TXSTAbits.TXEN //Tx enable or disable bit in TXSTA register
#define Continious_Rx_enable                RCSTAbits.CREN //continous recieption enable or disable bit in RCSTA register
#define Baud_rate_generator_speed           TXSTAbits.BRGH //baud rate generator speed (high or low) selection bit in TXSTA register
#define Baud_rate_generator_bits            BAUDCONbits.BRG16 //buad rate generator no. or bits selection bit (8 or 16 bits)in BAUDCON register
#define Baud_rate_generator_factor_lowByte  SPBRG //register to hold the serial port baud rate generator calculated baud factor LOW BYTE
#define Baud_rate_generator_factor_highByte SPBRGH //register to hold the serial port baud rate generator calculated baud factor HIGH BYTE 
 
/*---------------------------------------------------------------
            DEFINE USART RELATED INTERRUPT REGISTER BITS
----------------------------------------------------------------*/
#define Global_interrupt_enable     INTCONbits.GIEH //to enable or disable all interrupts (onchip and external)
#define Peripheral_interrupt_enable INTCONbits.GIEL //to enable or disable onchip peripheral interrupts
#define Tx_interrupt                PIE1bits.TXIE //to anable or disable transmitter interrupts
#define Rx_interrupt                PIE1bits.RCIE //to enable or disable reciever interrupts
#define Interrupt_priority_enable   RCONbits.IPEN //to enable or disable the priority level function on all interrupts
#define Tx_interrupt_priority       IPR1bits.TXIP //to change the priority level of the Tx interrupt (1=high,0=low)
#define Rx_interrupt_priority       IPR1bits.RCIP //to change the priority level of the Rx interrupt (1=high,0=low)
 
/*-----------------------------------------------------------------
                    USART RELATED FUNCTION DECLERATIONS
------------------------------------------------------------------*/
void Initialize_USART(void);
void Tx_char(unsigned char);
void InterruptHandlerLow();
 
/*-----------------------------------------------------------------
                        GLOBAL VARIABLE DECLERATIONS
------------------------------------------------------------------*/
unsigned char cUART_char;
unsigned char cUART_data_flg;
 
/*-------------------------------------------------------------------
                INTERRUPT HANDER CALL
-------------------------------------------------------------------*/
 
#pragma code InterruptVectorLow = 0x18
void InterruptVectorLow()
{
    _asm
    goto InterruptHandlerLow //jump to interrupt routine
    _endasm
 
}
#pragma code //End of pragma code
 
/*-------------------------------------------------------------------
                        INTERRUPT HANDLER ROUTINE
-------------------------------------------------------------------*/
 
void InterruptHandlerLow()
{
 
    if (PIR1bits.RCIF==1)//is interrupt occured by EUSART receive?, 
    //then RCREG is full we have new data (cleared when RCREG is read)
    { 
        if(RCSTA&0x06) //more efficient way than following commented method to check for reception error 
        //if(RCSTAbits.FERR==1 || RCSTAbits.OERR==1 )
        {
        RCSTAbits.CREN=0; //Overrun error (can be cleared by clearing bit CREN)
        cUART_char=getcUSART(); //clear Framing error 
        while(BusyUSART());
        RCSTAbits.CREN=1;
        cUART_data_flg = 1;
        PIR1bits.RCIF==0;
        }
        else
        {
        cUART_char = getcUSART(); // read new data into variable
        while(BusyUSART());
        cUART_data_flg = 1; // new data received. so enable flg
        PIR1bits.RCIF==0;
        }
    }
 
}
/*-------------------------------------------------------------------
                            MAIN FUNCTION
--------------------------------------------------------------------*/
 
void main(void)
{//start if main()
 
    //ADCON = 0; //all pins digital I/O
    Initialize_USART(); // init UART module
 
    while (1) // infinite loop which handles ncoming data as they arrive
    {
        if (cUART_data_flg==1)// if new data available, send it back through USART tx line (echo it)
        {
            Tx_char(cUART_char); 
            cUART_data_flg=0; // clear new data flag so one charactor will echoed once
        }
    }
 
}//end of main()
 
/*---------------------END OF MAIN FUNCTION-------------------------*/
/*--------------------------------------------------------------------
                    USART INITIALIZATION FUNCTION
---------------------------------------------------------------------*/
 
void Initialize_USART()
{
cUART_data_flg=0;
Tx_port = 0; //make C6 pin of port C as output pin for Tx
Rx_port =1; //make C7 pin of port C as input pin for Rx
 
    /*---------------------------------------------------------
            STATUS & CONTROL REGISTER BITS CONFIGURATION
    ----------------------------------------------------------*/
    Serial_port_enable =1; // Enable serial port
    Transmission_mode = 0; // Asynchronous transmission
    Tx_enable = 1; //Enable transmitter
    Continious_Rx_enable = 1; //Enable continous recieption on reciever
    Baud_rate_generator_speed = 1; //High speed
    Baud_rate_generator_bits = 0; //8bits
    Baud_rate_generator_factor_lowByte = 25; //Buad rate = 9600 for FOSC = 4MHz (See page 207 of PIC18F4520 datasheet)
    Baud_rate_generator_factor_highByte = 0;
 
    /*---------------------------------------------------------
            INTERRUPT REGISTER BITS CONFIGURATION
    ----------------------------------------------------------*/
 
    Global_interrupt_enable = 1; //enable all interrupts (onchip and external)
    Peripheral_interrupt_enable = 1; //enable onchip peripheral interrupts
    Tx_interrupt = 0; //disable Tx interrupt for start
    Rx_interrupt = 1; //enable Rx interrupt
    Interrupt_priority_enable = 1; //enable interrupt priorities
    Tx_interrupt_priority = 0; //low interrupt periority
    Rx_interrupt_priority = 0; //low interrupt periority
    
    /*----------------------------------------------------------*/
    
} //END OF INITIALIZATION FUNCTION
 
/*--------------------------END OF INITIALIZATION FUNCTION --------------*/
 
/*-----------------------------------------------------------------------
                            Tx CHARACTER FUNCTION
------------------------------------------------------------------------*/
void Tx_char(unsigned char c)
{
 
//putcUSART(c);
//TXSTAbits.TXEN=0;// disable transmission
//TXREG=c; // load txreg with data
putcUSART(c);
//TXSTAbits.TXEN=1; // enable transmission
//while(TXSTAbits.TRMT==1) // wait here till transmit complete
//{
//Nop();
//}
}