TMS570LS1224: ADC FIFO access

Varban Metodiev

Part Number: TMS570LS1224
Other Parts Discussed in Thread: HALCOGEN

Tool/software:

Hi (Jagadish),

I noticed that no matter what FIFO size of the ADC is configured (in HALCoGen), the generated code will always read the value of BUF0 (GxBUF[x].BUF0). For example, the adcGetData() function:

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uint32 adcGetData(adcBASE_t *adc, uint32 group, adcData_t * data)
{
    uint32  i;
    uint32  buf;
    uint32  mode;    
    uint32  index = (adc == adcREG1) ? 0U : 1U;
    uint32  intcr_reg = adc->GxINTCR[group];
    uint32  count = (intcr_reg >= 256U) ? s_adcFiFoSize[index][group] : (s_adcFiFoSize[index][group] - (uint32)(intcr_reg & 0xFFU));
    adcData_t *ptr = data; 
/* USER CODE BEGIN (16) */
/* USER CODE END */
    mode = (adc->OPMODECR & ADC_12_BIT_MODE);
    if(mode == ADC_12_BIT_MODE)
      {
        /** -  Get conversion data and channel/pin id */
        for (i = 0U; i < count; i++)
        {
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uint32 adcGetData(adcBASE_t *adc, uint32 group, adcData_t * data)
{
    uint32  i;
    uint32  buf;
    uint32  mode;    
    uint32  index = (adc == adcREG1) ? 0U : 1U;

	uint32  intcr_reg = adc->GxINTCR[group];
    uint32  count = (intcr_reg >= 256U) ? s_adcFiFoSize[index][group] : (s_adcFiFoSize[index][group] - (uint32)(intcr_reg & 0xFFU));
    adcData_t *ptr = data; 

/* USER CODE BEGIN (16) */
/* USER CODE END */

    mode = (adc->OPMODECR & ADC_12_BIT_MODE);

    if(mode == ADC_12_BIT_MODE)
      {
        /** -  Get conversion data and channel/pin id */
        for (i = 0U; i < count; i++)
        {
          buf        = adc->GxBUF[group].BUF0;
		  /*SAFETYMCUSW 45 D MR:21.1 <APPROVED> "Valid non NULL input parameters are only allowed in this driver" */
          ptr->value = (uint16)(buf & 0xFFFU);
          ptr->id    = (uint32)((buf >> 16U) & 0x1FU);
          /*SAFETYMCUSW 567 S MR:17.1,17.4 <APPROVED> "Pointer increment needed" */
		  ptr++;
        }
      }
      else
      {
        /** -  Get conversion data and channel/pin id */
        for (i = 0U; i < count; i++)
        {
          buf        = adc->GxBUF[group].BUF0;
		  /*SAFETYMCUSW 45 D MR:21.1 <APPROVED> "Valid non NULL input parameters are only allowed in this driver" */
          ptr->value = (uint16)(buf & 0x3FFU);
          ptr->id    = (uint32)((buf >> 10U) & 0x1FU);
          /*SAFETYMCUSW 567 S MR:17.1,17.4 <APPROVED> "Pointer increment needed" */
		  ptr++;
        }
      }


    adc->GxINTFLG[group] = 9U;

    /**   @note The function adcInit has to be called before this function can be used.\n
    *           The user is responsible to initialize the message box.
    */

/* USER CODE BEGIN (17) */
/* USER CODE END */

    return count;
}

And inside adcBase_t, it looks like this:

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    struct
    {
        uint32 BUF0;           /**< 0x0090,0x00B0,0x00D0: Group 0-2 result buffer 1 register    */
        uint32 BUF1;           /**< 0x0094,0x00B4,0x00D4: Group 0-2 result buffer 1 register    */
        uint32 BUF2;           /**< 0x0098,0x00B8,0x00D8: Group 0-2 result buffer 2 register    */
        uint32 BUF3;           /**< 0x009C,0x00BC,0x00DC: Group 0-2 result buffer 3 register    */
        uint32 BUF4;           /**< 0x00A0,0x00C0,0x00E0: Group 0-2 result buffer 4 register    */
        uint32 BUF5;           /**< 0x00A4,0x00C4,0x00E4: Group 0-2 result buffer 5 register    */
        uint32 BUF6;           /**< 0x00A8,0x00C8,0x00E8: Group 0-2 result buffer 6 register    */
        uint32 BUF7;           /**< 0x00AC,0x00CC,0x00EC: Group 0-2 result buffer 7 register    */
    } GxBUF[3U];                                                                               
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    struct
    {
        uint32 BUF0;           /**< 0x0090,0x00B0,0x00D0: Group 0-2 result buffer 1 register    */
        uint32 BUF1;           /**< 0x0094,0x00B4,0x00D4: Group 0-2 result buffer 1 register    */
        uint32 BUF2;           /**< 0x0098,0x00B8,0x00D8: Group 0-2 result buffer 2 register    */
        uint32 BUF3;           /**< 0x009C,0x00BC,0x00DC: Group 0-2 result buffer 3 register    */
        uint32 BUF4;           /**< 0x00A0,0x00C0,0x00E0: Group 0-2 result buffer 4 register    */
        uint32 BUF5;           /**< 0x00A4,0x00C4,0x00E4: Group 0-2 result buffer 5 register    */
        uint32 BUF6;           /**< 0x00A8,0x00C8,0x00E8: Group 0-2 result buffer 6 register    */
        uint32 BUF7;           /**< 0x00AC,0x00CC,0x00EC: Group 0-2 result buffer 7 register    */
    } GxBUF[3U];

I am still wondering how the FIFO works under the hood, and more specifically:

1. Where are BUF1 to BUF7 used (what is their purpose)?

2. Does a read over one of that memory locations (for example, BUF0) will automatically rotate the hardware FIFO (move the tail)?

Thanks and regards,

Varban

4 months ago

+1 jagadish gundavarapu 4 months ago

TI__Guru 62570 points

Hi Varban,

There are couple of ways in ADC results(i mean converted data) reading:

One is FIFO based method and other one is directly accessing the memory.

Here adcGetData using FIFO based method only. I mean BUF0 is a FIFO only.

We can read any of the buffer from BUF0 to BUF7 because they are all will hold same converted results only. For the first time these FIFO Queue will hold the first converted data, and if we read this data then the FIFO will get update with the other data in the ADC RAM which is converted right after the first converted data and this process will continue.

Please refer TRM once for more details.

--
Thanks & regards,
Jagadish.

0 Varban Metodiev 4 months ago in reply to jagadish gundavarapu

Intellectual 690 points

Hi Jagadish,

Thank you for the clear explanation!

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TMS570LS1224: ADC FIFO access