TNS310f2812 and ADC7734

Hi,

I would like to use a DAC 7734 with the 2812 DSP. The DAC uses a 24 bit register. The DSP SPI Register are 16 bits.

I do not manage to program the 2812 SPI protocole  to send words of 24 bits.

The programme of spi configuration :

void InitSpi(void)
{
        EALLOW;
    GpioDataRegs.GPFDAT.bit.GPIOF6 = 1;       //desactivation /CS du DAC
     GpioDataRegs.GPBDAT.bit.GPIOB1 = 1;    // tous les dac reg latched
    GpioDataRegs.GPBDAT.bit.GPIOB3 = 1;    // input reg sel latched
    GpioDataRegs.GPDDAT.bit.GPIOD0 = 1;    // resetsel high
    GpioDataRegs.GPBDAT.bit.GPIOB5 = 0;    // reset de toutes les sorties
   
 
    SpiaRegs.SPICCR.all = 0x000F;   
    // Bit 7 , Reset = 0 :
    // Bit 6 , Clock Polarity = 1 : data output on falling edge of CLK
    //       , together with CLOCK PHASE = 1 : data output is one half cycle before
    //       , falling edge pf SPICLK
    // Bit 5 , reserved
    // Bit 4 , SPILBK = 0 : no loopback mode
    // Bit 3-0 , Chars = 1111 : 16 bit data transfer

    SpiaRegs.SPICTL.all =0x000E;
    // Bit 7-5 : reserved
    // Bit 4 , Overrun INT Enable = 0 : Disable Receiver Overrun Interrupt
    // Bit 3 , Clock-Phase = 1 , one half clock delay
    // Bit 2 , Master/Slave = 1 ,  MASTER
    // Bit 1 , Talk = 1 ,  Enable Transmission
    // Bit 0 , SPI INT ENA = 0 , No SPI - Interrupts
       
    SpiaRegs.SPIBRR = 0x7F;  //11 minimum a ne pas depasser
    // SPI Baud Rate =  LSPCLK / ( SPIBRR + 1)
    //                 =  37,5 MHz / ( 124 + 1 )
    //                 =  300 kHz (3.125Mhz si 11)

    SpiaRegs.SPICCR.bit.RESET = 1; // relinquish SPI from reset
   // SpiaRegs.SPIFFTX.bit.TXFIFORESET=1;        // SPI FIFO out of reset
    GpioDataRegs.GPBDAT.bit.GPIOB5 = 1;      // fin reset DAC
    EDIS;
   
}

In the main loop :

  GpioDataRegs.GPFDAT.bit.GPIOF6 = 0;  // activation du chip avec /cs
    SpiaRegs.SPITXBUF = 0x8888;
   
    while (SpiaRegs.SPISTS.bit.INT_FLAG == 0) ;
    dummy=SpiaRegs.SPIRXBUF;     clear 'SPI INT FLAG' by reading SPIBRXUF
 
    SpiaRegs.SPITXBUF = 0x5555;    
    while (SpiaRegs.SPISTS.bit.INT_FLAG == 0) ;
     dummy=SpiaRegs.SPIRXBUF;    clear 'SPI INT FLAG' by reading SPIBRXUF

With this code, there is a delay between both words of 16 bits. This delay depends on the period of sampling. I shall like sending a word of 24 bits without delay after the first 16 bits.

Can you help me please ?