KL27 Adc locked

[attiliorossi321]

I'd like to use the internal AD converter. But it doesn't work correctly.

I connected a continue voltage on PTB 0 labeled as ADC0/SE8 adc channel.(using FRDMKL27)

I follow the data sheet just to start the module but the register R it is always at the value of 65535.

If I break at ADC0 interrupr handler I see this.

The ADc is triggered from a timer every 500 ms.

What's miss on my code ?

Any suggestion ?

Thanks in advance.

Attilio

void ADC0_IRQHandler(void)
{
    static UINT32 value = 0;

    value = ADC0->R[0];
}

BOOL Adc_Calibration(void)
{
    UINT16         cal_data;
    ADC_Type    *adc;

    adc = ADC0;                              // just to see the register in the debug window

    adc->CFG1 |= ADC_CFG1_ADICLK(0x01)  +    // adc input clock = busclk/ 2 --> (24 Mhz / 2) = 12 Mhz
                 ADC_CFG1_ADIV(2)       +    // adc division = 8 --> adc clock = 12 Mz / 8 = 1Mhz
                 ADC_CFG1_ADLPC(0)      +    // no low power
                 ADC_CFG1_ADLSMP(0x01)  +   // long sample time
                 ADC_CFG1_MODE(0x03);       // with DIFF = 0 --> 16 bit single ended

    adc->SC2 = 0x00;                        // software trigger selected
                                            // compare function disabled
                                            // DMA transfert disabled
                                            // voltage ref is default ref (vrefh / vrefl)

    adc->SC3 |= ADC_SC3_AVGE_MASK +        // enable hw average
                ADC_SC3_AVGS(3)   +        // set for 32 samples
                ADC_SC3_CAL_MASK;          // start calibration

    while(adc->SC3 & ADC_SC3_CAL_MASK);   // wait for calibration end

    if(adc->SC3 & ADC_SC3_CALF_MASK)      // check calibration success ?
        return FALSE;                     // calibration was fault

// compute & store calibration data
    cal_data  = 0;
    cal_data += adc->CLPS + adc->CLP4 + adc->CLP3 +    
                adc->CLP2 + adc->CLP1 + adc->CLP0;

    cal_data >>= 1;
    cal_data |= 0x8000;
    adc->PG = cal_data;

    cal_data  = 0;
    cal_data += adc->CLMS + adc->CLM4 + adc->CLM3 +
                adc->CLM2 + adc->CLM1 + adc->CLM0;

    cal_data >>= 1;
    cal_data |= 0x8000;
    adc->MG = cal_data;

    adc->SC3 &= ~ADC_SC3_CAL_MASK;                                            // clear CAL bit

    return TRUE;
}

void InitAdc(void)
{
    SIM->SCGC6 |= SIM_SCGC6_ADC0_MASK;              // adc0 clock gating

    if(Adc_Calibration() == FALSE)
    {
        ErrorTrap();                               // just for debug
    }

    // change adc config after calibration
    ADC0->CFG1 |= ADC_CFG1_ADICLK(0x01) +         // adc input clock = busclock --> 24 Mhz
                  ADC_CFG1_ADIV(0)      +         // adc division = 1 --> adc clock = 24 Mz
                  ADC_CFG1_ADLPC(0)     +        // no low power
                  ADC_CFG1_ADLSMP(0x01) +         // long sample time
                  ADC_CFG1_MODE(0x03);            // with DIFF = 0 --> 16 bit single ended

    ADC0->SC1[0] |= ADC_SC1_ADCH(0x1F);             // disable ADC module

    ConnectInterruptToCortex(ADC0_IRQn);            // set ADC0 interrupts
}

void TriggerAdc(void)
{
    ADC0->SC1[0] = ADC_SC1_ADCH(8) | ADC_SC1_AIEN_MASK;
}

void main(void)
{
  InitAdc();
 
  ENABLE_INTERRUPTS;
  while(1)
  {
 
  }
}

[nxf58474]

Hello Attilio,

Hope you are going well. We have drivers examples in the SDK. You can download it here: SDK Builder. To see all driver examples you need to select the FRDM-KL27Z board. I recommend consulting the adc16_interrupt example, it does the ADC initialization and calibration. Try this example and, if it works, I can help you to modify your initialization function, or you can take the example and adapt it to your desired configuration.

Let me know your results and if you have further questions.

Best Regards,

Ricardo

[attiliorossi321]

Hi Ricardo.

Thanks for your answer.

I'm looking for adc driver examples as you told me. To be onest about my problem, I just found out an hardware problem too.

In my think, the sdk are very useful but I can prefer to write the driver. But now seem to work properly. I have to adjust the adc hardware interrupt and remove the PRINTF console debug. It is a useful function but very very slow.

Best regards.

Attilio

[nxf58474]

Hello Attilio,

I'm glad you were able to solve this. The printf function should only be used for debugging, however, for the actual implementation of your application, minimal or no use should be made, since you mention that it slows down the application, since it takes time to perform the printing routine and return to the application.

If you have any questions please don't hesitate to ask.

Best Regards,

Ricardo