MSP432P401R: Launchpad uses SPI problem

Part Number: MSP432P401R

Hi ,

I use the spi of the Launchpad to connect to the MAX7219.

This is my hardware connection:

I am using three pins p9.4, p9.5 and p9.7.

Below is my source code.

#include "msp.h"

#include <stdint.h>

#include "Clock.h"

#include "string.h"

#include "driverlib.h"

void SPI_INIT(void)

{

    EUSCI_A3->CTLW0 = 0x0001;             // hold the eUSCI module in reset mode

    EUSCI_A3->CTLW0 = 0xAD83;  //a

    EUSCI_A3->BRW = 120;

     // modulation is not used in SPI mode, so clear UCA3MCTLW

    EUSCI_A3->MCTLW = 0;

    P9->SEL0 |= 0xB0;

    P9->SEL1 &= ~0xB0;// configure P9.7, P9.5, and P9.4 as primary module function

   EUSCI_A3->CTLW0 &= ~0x0001;           // enable eUSCI module

    EUSCI_A3->IE &= ~0x0003;              // disable interrupts

}

void Write_Max7219_byte(uchar DATA)

{

    while(EUSCI_A3->STATW & 0x01); 

    while((EUSCI_A3->IFG & 0x02))

    EUSCI_A3->TXBUF = DATA;

}

void Write_Max7219(uchar address,uchar dat)

{

    Write_Max7219_byte(address);           

    Write_Max7219_byte(dat);               

}

void Init_MAX7219(void)

{

    Write_Max7219(0x09, 0x00);      

    Write_Max7219(0x0a, 0x03);      

    Write_Max7219(0x0b, 0x07);      

    Write_Max7219(0x0c, 0x01);       

}

void clear(void)

{

    Write_Max7219(0x01,0x00);

    Write_Max7219(0x02,0x00);

    Write_Max7219(0x03,0x00);

    Write_Max7219(0x04,0x00);

    Write_Max7219(0x05,0x00);

    Write_Max7219(0x06,0x00);

    Write_Max7219(0x07,0x00);

    Write_Max7219(0x08,0x00);

}

/**

 * main.c

 */

void main(void)

{

    unsigned char test_buf[]={0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01};

    WDT_A_holdTimer();

    Clock_Init48MHz();

    SPI_INIT();

    uint i,j;

    Clock_Delay1ms(50);

    Write_Max7219(0x0f,0x01);

    Clock_Delay1ms(1000);

    Write_Max7219(0x0f,0x00);

    Clock_Delay1ms(50);

    Init_MAX7219();

    Clock_Delay1ms(50);

    clear();

    Clock_Delay1ms(1000);

    while(1){

    for(i = 0;i < 8;i++){

        Write_Max7219(i+1,test_buf[i]);

    }

    if(i == 8)

        i = 0;

    }

}

I do not use interrupts, directly manipulate registers to control data transmission.

But when I send the character array "test_buf", the first five data are ok, and the last three send past results errors.

When I execute to Write_Max7219 (6,0x04), the result from the digital tube is the execution of Write_Max7219 (6,0x04) and Write_Max7219 (8,0x06).

I suspect that after the TXBUF data is transferred to the transmit shift register, the shift register is not cleared when the next data is sent.

Because I used CCS debugging to see that the value of the TXBUF register is the same as what I wrote.

How can I tell if something is causing this error, or can I manually clear the transmit shift register to eliminate the effects of the shift register?

Thanks,

Better