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Just an example about using SPI

Dear All,

I'm working on SPI communication on two LPC2138. I prepared a board based on MCB2130 and just want that first LPC2138 works as Master and second works as Slave. I want to make them communicate as bi-directional and via interrupt. Could you please give me an example works on Realview Compiler? I couldn't make work the example spi file in lpc21xx_insidersguide.zip
I also couldn't make work which is listed in philips LPC2138 pages.

Opti

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0 Opti Zyme over 16 years ago in reply to Andy Neil

Hellow,

I took your advice and started to debug example code. I realized that spi startup code is a little problem. Here is my code and schematic :

#include <LPC21xx.H>                            /* LPC21xx definitions */
#include <string.h>                            /* LPC21xx definitions */
#define SPI_OK 0
#define SPI_ERROR 1
#define SPI_BUSY 2


static unsigned char   state;      // State of SPI driver
//static unsigned char   msg[5];       // pointer to SPI data buffer
static unsigned char   msg[5];       // pointer to SPI data buffer
static unsigned char   count;      // nr of bytes send/received
long timeval;

void wait (void)  {                             /* wait function */
  unsigned long i;

  i = timeval;
  while ((i + 10) != timeval);                  /* wait 100ms */
}

/* Timer Counter 0 Interrupt executes each 10ms @ 60 MHz CPU Clock */
void tc0 (void) __irq  {
  ++timeval;
  T0IR        = 1;                            // Clear interrupt flag
  VICVectAddr = 0;                            // Acknowledge Interrupt
}

/* Setup the Timer Counter 0 Interrupt */
void init_timer (void) {
  T0MR0 = 149999;                             // 10mSec = 150.000-1 counts
  T0MCR = 3;                                  // Interrupt and Reset on MR0
  T0TCR = 1;                                  // Timer0 Enable
  VICVectAddr0 = (unsigned long)tc0;          // set interrupt vector in 0
  VICVectCntl0 = 0x20 | 4;                    // use it for Timer 0 Interrupt
  VICIntEnable = 0x00000010;                  // Enable Timer0 Interrupt
}

void vSPI0_ISR(void) __irq
{
    if ((S0SPSR & 0xF8) == 0x80)
    {
        ++count;
                if (count < 40)
            S0SPDR = msg[count-1];         // sent next byte
        else
            state = SPI_OK;        // transfer completed
    }
    else                           // SPI error
    {
        *msg = S0SPDR;             // dummy read to clear flags
        state = SPI_ERROR;
    }
    S0SPINT = 0x01;                // reset interrupt flag
    VICVectAddr = 0;               // reset VIC
}

static void SPI_Init(void)
{

        VICVectAddr2 = ( unsigned long ) vSPI0_ISR;
        VICVectCntl2 = 0x02A;
        VICIntEnable |= 0x0400;

        PINSEL0=0x5500;   // Configure Pin Connect Block
        VPBDIV=0x01;      // Set pclk to same as cclk
        S0SPCCR=0x08;     // Set to highest speed for SPI at 60 MHz -> 7.5 MHz
        VICIntSelect &= ~( 0x0400 );
        S0SPINT=0x01;     // Device selected as master
        S0SPCR=0xA0;
}

int main (void)  {
  unsigned int j;                               /* LED var */
  unsigned long volatile start;  // volatile avoids loop optimization

/*
  for (start = 0; start < 10000000; start++) {
    ;    // wait for debugger connection (about 0.3 sec)
  }
*/

        SPI_Init();

        IODIR1 = 0xFF0000;                            /* P1.16..23 defined as Outputs */
        init_timer();

        S0SPDR=0x42;
        strcpy(msg, "OPTIZ");

        count = 0;

        while (1)  {
    for (j = 0x010000; j < 0x800000; j <<= 1) { /* Blink LED 0,1,2,3,4,5,6 */
      IOSET1 = j;                               /* Turn on LED */
      wait ();                                  /* call wait function */
      IOCLR1 = j;                               /* Turn off LED */
    }
    for (j = 0x800000; j > 0x010000; j >>=1 ) { /* Blink LED 7,6,5,4,3,2,1 */
      IOSET1 = j;                               /* Turn on LED */
      wait ();                                  /* call wait function */
      IOCLR1 = j;                               /* Turn off LED */
    }
  }
}

img155.imageshack.us/.../spi.jpg
img195.imageshack.us/.../osc.jpg

I couldnt fix "count" variable. If i decrease count value, it stops.. What do you say about this?

Optizyme

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