LPC2148 SPI Problem

Doesn't look readable.

You forgot to tag it as code.

You forgot to use comments, to actually document your code. Magic constants doesn't help you.

I apologize for the inconvenience...here is the code with comments:

The code sends a predefined data and on getting the same data back ,changes the state of its pins .LPC2148 acts as a master to a device which relays the same data sent to it.

#include  <lpc214x.h>              //Includes LPC2148 register definitions


void spi_init();                        //To define SPI
void spi_send(char p);
char spi_receive();

int  main(void)
{
        char p;
        int i=0;
   PINSEL0 = (1<<8)|(1<<10)|(1<<12)|(1<<14);                // Enable MISO MOSI SCK and Slave Select
   PINSEL1 = 0x00000000;
   PINSEL2 = 0x00000000;
         IO0DIR = (1<<14);
         IO0CLR |=(1<<14);                                        //Keep slave select as negetive always
   IO1DIR = (1<<19) | (1<<18) | (1<<17) | (1<<16);
                spi_init();                                     //Initialize spi

        while (1)
        {
                spi_send('0');                                  //Send a character and receive the same character
                while(p!='0')
                {
                        p=spi_receive();
                }

                spi_send('x');
                while(p!='x')
                {
                        p=spi_receive();
                }

                spi_send('f');
                while(p!='f')
                {
                        p=spi_receive();
                }

                spi_send('f');
                while(p!='f')
                {
                        p=spi_receive();
                }
                i+=1;
                p='o';
                switch(i%4)     //change state of pin when the given configuration is sent
                {
                        case 1:
                        IO1CLR=(1<<19)|(1<<18)|(1<<17)|(1<<16);
                        IO1SET=(1<<19);
                        break;
                        case 2:
                        IO1CLR=(1<<19)|(1<<18)|(1<<17)|(1<<16);
                        IO1SET=(1<<18);
                        break;
                        case 3:
                        IO1CLR=(1<<19)|(1<<18)|(1<<17)|(1<<16);
                        IO1SET=(1<<17);
                        break;
                        case 0:
                        IO1CLR=(1<<19)|(1<<18)|(1<<17)|(1<<16);
                        IO1SET=(1<<16);
                        break;

}
}
}
void spi_init()
{
        S0SPCR|=(1<<5);          //Master mode
        S0SPCCR=0x60;            //12500 Hz clock

}
void spi_send(char p)
{
        int value;
        value=(int)p;
        S0SPDR = value;
  while (!(S0SPSR & 0x80));         //checks for data flag to go off
}
char spi_receive()
{
        char p;
  while (!(S0SPSR & 0x80));          //waits till data is received.
        p=(char)S0SPDR;
        return p;
}

----------------------------------
STARTUP CODE (startup_LPC17xx.s)
----------------------------------
Reset_Handler PROC
EXPORT Reset_Handler [WEAK]
IMPORT SystemInit
IMPORT __main
MOV R0,#0
MSR CONTROL, R0
LDR R0, =SystemInit
BLX R0
LDR R0, =__main
BX R0
ENDP

----------------------------
EXECUTE USER CODE FUNCTION
----------------------------
void execUserCode( void )
{ __disable_irq( );
SCB -> VTOR = ( USER_FLASH_START & 0x1FFFFF80 );
bootJump( USER_FLASH_START ); // User Flash start is the position of the vector table for the app }

-----------------------------------
BOOT JUMP TO APPLICATION FUNCTION
-----------------------------------
__asm void bootJump( U32 address )
{ LDR SP, [R0]
LDR PC, [R0, #4]
}

Thank you for your answer

I use flash magic to program the MCU and load the value of the flash start and all...

I haven't used any of the above code for UART and it works.So I feel that is not the solution.
Is there something else wrong with the code?or am i forgetting to initialize something important?

I have tried to loop back MOSI and MISO and test.

The code appears to be working sometimes based on the led signals...
This is what I could infer:

1)code is sending a character
2)Code is receiving a character
3)The received character is not 0xff or the looped back character but something else.

Is there a specific clock i need to use for spi?I use 12Mhz and use 1/8 th for spi.
Should I initialize anything for loopback or receive?

The datasheet says read the S0SPSR to clear register before receiving data...how do I do that?

Here is the code for your reference

#include  <lpc214x.h>              //Includes LPC2148 register definitions


void spi_init();                        //To define SPI
void spi_send(char p);
char spi_receive();

int  main(void)
{

        char p='l';
        int i=0,j=0,k=0;
        for(j=0;j<12000;j++)
                        {
                                        for(k=0;k<1000;k++);
                        }
   PINSEL0 = (1<<8)|(1<<10)|(1<<12)|(1<<14);                // Enable MISO MOSI SCK and Slave Select
   PINSEL1 = 0x00000000;
   PINSEL2 = 0x00000000;
         IO0DIR = (1<<14);
         IO0SET |=(1<<14);                                        //Keep slave select as negetive always
   IO1DIR = (1<<19) | (1<<18) | (1<<17) | (1<<16);
                spi_init();                                     //Initialize spi

        while (1)
        {

                spi_send('0');

        //Send a character and receive the same character
                while(p!='0')
                {

                        p=spi_receive();
                        if(p==(char)0xff)
                        {
                                IO1CLR=(1<<19)|(1<<18)|(1<<17)|(1<<16);                 //to check if no data is received without interrupt flag
                        }
                }
                while(p=='0')
                {
                        IO1CLR=(1<<19)|(1<<18)|(1<<17)|(1<<16);                         //if data is received properly
                        IO1SET=(1<<19)|(1<<17)|(1<<16);
                        while(1);
                }


}
}

void spi_init()
{
        S0SPCR|=0x20;         //Master Mode
        S0SPCCR=0x8;

}
void spi_send(char p)
{
        IO0CLR |=(1<<14);
        S0SPDR = p;
  while ((!S0SPSR & 0x80));
        S0SPSR &=~ 0x80;
        IO0SET |=(1<<14);
}
char spi_receive()
{
        char p;
        IO0CLR |=(1<<14);
        S0SPDR=0xff;
        IO1SET=(1<<18)|(1<<17)|(1<<16);     //to check if function is entered
  while ((!S0SPSR & 0x80));
        p=S0SPDR;
        IO1SET=(1<<19)|(1<<17)|(1<<16);     //to check if data is received
        return p;
        IO0SET |=(1<<14);
}

Any help is gratefully appreciated.

Thank You