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help request: sending 128 16-bit values with buffered SPI (RM46)

Jan Cumps
Guru 15740 points
Other Parts Discussed in Thread: HALCOGEN

I'm working on a design that matches the Educational BoosterPack MKII display with Hercules microcontrollers.

I am struggling with a particular problem: Sending 128 16-bit  values  with MibSPI in one go.
I am able to send 128 separate 16-bits values with MIBSPI. 

I'm using MIBSPI 3.

I created a data format for 16 bits.

I created a transfer group that uses that group.

When calling the MIBSpi Functions (TXDATA contains 128 16-BIT values)

    mibspiSetData(mibspiREG3, 2, &TXDATA[0]);
    mibspiTransfer(mibspiREG3, 2 );
    while(!(mibspiIsTransferComplete(mibspiREG3, 2))) {
    }

I don't get the expected results.

In the HALCoGen generated mibspiSetData() function , the "start" and "end" variable get value "1" and "2".

I was expecting to have the a value of  0 and 127.

Because the values are 1 and 2, the mibspiSetData() function only copies one value into the MIBSpi Buffers.

  • 0
    TI__Guru**** 183956 points

    Hi Jan,

     What is the buffer length you configure for group0 and group1?

     The "start" should be the PSTART for group2 and the "end" should be the PSTART for group3. I'm seeing 0 and 127 for the start and end.

       uint32 start  = (mibspi->TGCTRL[group] >> 8U) & 0xFFU;

       uint32 end    = (group == 7U) ? (((mibspi->LTGPEND & 0x00007F00U) >> 8U) + 1U) : ((mibspi->TGCTRL[group+1U] >> 8U) & 0xFFU);

    mibspiREG3->TGCTRL[2U] = (uint32)((uint32)0U << 30U) /* oneshot */
    | (uint32)((uint32)1U << 29U) /* pcurrent reset */
    | (uint32)((uint32)TRG_ALWAYS << 20U) /* trigger event */
    | (uint32)((uint32)TRG_DISABLED << 16U) /* trigger source */
    | (uint32)((uint32)(0U+0U) << 8U); /* start buffer */

    mibspiREG3->TGCTRL[3U] = (uint32)((uint32)1U << 30U) /* oneshot */
    | (uint32)((uint32)0U << 29U) /* pcurrent reset */
    | (uint32)((uint32)TRG_ALWAYS << 20U) /* trigger event */
    | (uint32)((uint32)TRG_DISABLED << 16U) /* trigger source */
    | (uint32)((uint32)(0U+0U+127U) << 8U); /* start buffer */

  • 0
    Guru 15740 points

    (if I manipulate the values of start and end in debug mode, mibspi nicely sends my data)

  • 0 in reply to Charles Tsai
    Guru 15740 points

    Group 0 and 1 both have 1;

    I use group0 to send single 8-bit values,

    and group1 to send single 16-bit values.

    Here's the values in the HalCoGen generated init():

        /** - initialize transfer groups */
    mibspiREG3->TGCTRL[0U] = (uint32)((uint32)1U << 30U)  /* oneshot */
                           | (uint32)((uint32)0U << 29U)  /* pcurrent reset */
                           | (uint32)((uint32)TRG_ALWAYS << 20U)  /* trigger event */
                           | (uint32)((uint32)TRG_DISABLED << 16U)  /* trigger source */
                           | (uint32)((uint32)0U << 8U);  /* start buffer */

    mibspiREG3->TGCTRL[1U] = (uint32)((uint32)1U << 30U)  /* oneshot */
                           | (uint32)((uint32)0U << 29U)  /* pcurrent reset */
                           | (uint32)((uint32)TRG_ALWAYS << 20U)  /* trigger event */
                           | (uint32)((uint32)TRG_DISABLED << 16U)  /* trigger source */
                           | (uint32)((uint32)1U << 8U);  /* start buffer */

    mibspiREG3->TGCTRL[2U] = (uint32)((uint32)0U << 30U)  /* oneshot */
                           | (uint32)((uint32)1U << 29U)  /* pcurrent reset */
                           | (uint32)((uint32)TRG_ALWAYS << 20U)  /* trigger event */
                           | (uint32)((uint32)TRG_DISABLED << 16U)  /* trigger source */
                           | (uint32)((uint32)(1U+1U) << 8U);  /* start buffer */

    mibspiREG3->TGCTRL[3U] = (uint32)((uint32)1U << 30U)  /* oneshot */
                           | (uint32)((uint32)0U << 29U)  /* pcurrent reset */
                           | (uint32)((uint32)TRG_ALWAYS << 20U)  /* trigger event */
                           | (uint32)((uint32)TRG_DISABLED << 16U)  /* trigger source */
                           | (uint32)((uint32)(1U+1U+127U) << 8U);  /* start buffer */

  • 0 in reply to Jan Cumps
    Guru 15740 points

    HALCoGen config complete:

  • 0 in reply to Jan Cumps
    TI__Guru**** 183956 points
    Hi Jan,

    I think the reason is that bit15 in the TGCTRL register is reserved. When (1U+1U+127U) << 8U is used the upper bit is chopped off. So what is really stored in the TGCTRL[3U] for the PSTART is only 1.
  • 0 in reply to Charles Tsai
    TI__Guru**** 183956 points
    Hi Jan,
    Also that MibSPI3 only supports 128 buffers. The three transfer groups together exceeds 128.
  • 0 in reply to Charles Tsai
    Guru 15740 points

    Thanks, . I didn't know that the groups add up to the buffer limit.
    I'll restructure my code to get the 3 groups to fit into 128.
    I'll report back...

  • 0 in reply to Jan Cumps
    Guru 15740 points
    Reporting success.
    I have set my buffer for group2 to 64.
    When debugging, start is 2, end is 66. Yes!
    Everything works perfectly. I get 64 16-bit values streamed in one go.

    Thank you very much, .
  • 0 in reply to Jan Cumps
    TI__Guru**** 183956 points
    Hi Jan,
    Glad your problem is resolved.