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CCS/TMS320F28069: F28069 SCI communication problem

WANG NING
Intellectual 490 points
Part Number: TMS320F28069

Tool/software: Code Composer Studio

Hello,

I am programming F28069 device to transfer a block (256 words) of data to PC through Serial Communication Interface.

Looks like I have to put a delay between every two words as below:

            for(index=0;index<256;index++)
            {
                SciaRegs.SCITXBUF = block_0[index] ;
                DELAY_US(800);
            }

otherwise there are always some data missing,  less delay causes more data miss. without a delay, there are only 5 words transferred.

I wonder if this is correct. Because with fifo enabled, I don't think a delay is needed here. Plus, the baudrate setup matches between PC and the device. And the fifo is configured as follows,

void scia_init(void)
{
    //fifo init
    SciaRegs.SCIFFTX.all=0xE040;  //SCI Reset,SCI FIFO enable,TXFIFO int clr
    SciaRegs.SCIFFRX.all=0x2062;  //RXFIFO int clr, RXFIFO int enable
    SciaRegs.SCIFFCT.all=0x0;

    //sci init
    SciaRegs.SCICCR.all =0x0007;   // 1 stop bit,  No loopback
                                   // No parity,8 char bits,
                                   // async mode, idle-line protocol
    SciaRegs.SCICTL1.all =0x0003;  // enable TX, RX, internal SCICLK,
                                   // Disable RX ERR, SLEEP, TXWAKE
    SciaRegs.SCICTL2.all =0x0003;
    SciaRegs.SCICTL2.bit.RXBKINTENA =1;
    // Baud Rate ~=14400
    SciaRegs.SCIHBAUD    =0x0000;
    SciaRegs.SCILBAUD    =0x00C2;

    SciaRegs.SCICTL1.all =0x0023;     // Relinquish SCI from Reset
}

Can someone point out if I get anything wrong?

Thanks

Ning

  • 0
    TI__Mastermind 32995 points
    The F2806x only has a FIFO which is 4 bytes deep. It is quite possible that you are overflowing the FIFO.

    Instead of using a delay, before writing to TXBUF, wait until the TXFFST is less than 4, and then write the data to TXBUF.

    sal
  • 0 in reply to Sal Pezzino
    Intellectual 490 points
    ok thanks. So, just to confirm, if I want to send data as fast as possible, I should set TXFFIL4-0 = 3, that is whenever there is a space in the FIFO, transfer a byte to TXBUF. is it correct?
  • 0 in reply to WANG NING
    TI__Mastermind 32995 points
    Yes, that is correct.... if you are using interrupts. TXFFIL is the FIFO interrupt level. If there are three elements in the FIFO or less, the SCI will generate a TX interrupt, in which you would send data by writing it to the TXBUF.

    sal