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ADC_inputvoltage

Hi, I m using intel quark d2000, for adc if i apply the voltage from the board(D2000 board) it giving correct digital value but if i give the analog value from outside power supply then it is showing incorrect digital value.i am using this program .

/*

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# include "qm_adc.h"

# include "qm_interrupt.h"

# include "qm_scss.h"

# include "qm_pinmux.h"

/* QMSI ADC app example

*

*/

# define NUM_CHANNELS (2)

# define NUM_SAMPLES_POLLED (10)

# define NUM_SAMPLES_INTERRUPT (50)

int main(void)

{

# if (QUARK_D2000)

int i;

qm_adc_config_t cfg;

qm_adc_xfer_t xfer;

qm_adc_channel_t channels[] = {QM_ADC_CH_8, QM_ADC_CH_9};

uint32_t samples_polled[NUM_SAMPLES_POLLED] = {0};

QM_PUTS("\nADC example app start");

/* Enable the ADC and set the clock divisor */

clk_periph_enable(CLK_PERIPH_CLK | CLK_PERIPH_ADC |CLK_PERIPH_ADC_REGISTER);

clk_adc_set_div(100); /* ADC clock is 320KHz @ 32MHz */

/* Set up pinmux */

qm_pmux_select(QM_PIN_ID_8, QM_PMUX_FN_1);

qm_pmux_select(QM_PIN_ID_9, QM_PMUX_FN_1);

qm_pmux_input_en(QM_PIN_ID_8, true);

qm_pmux_input_en(QM_PIN_ID_9, true);

/* Set the mode and calibrate */

qm_adc_set_mode(QM_ADC_0, QM_ADC_MODE_NORM_CAL);

qm_adc_calibrate(QM_ADC_0);

/* Set up config */

cfg.window = 2; /* Clock cycles between the start of each sample */

cfg.resolution = QM_ADC_RES_12_BITS;

qm_adc_set_config(QM_ADC_0, &cfg);

/*******************************

* ADC polled mode example

******************************/

QM_PUTS("ADC polled mode");

/* Set up xfer */

xfer.ch = channels;

xfer.ch_len = NUM_CHANNELS;

xfer.samples = samples_polled;

xfer.samples_len = NUM_SAMPLES_POLLED;

/* Run the conversion */

if (qm_adc_convert(QM_ADC_0, &xfer))

{

QM_PUTS("ERROR: qm_adc_convert failed");

return 1;

}

/* Print the values of the samples */

for (i = 0; i < NUM_SAMPLES_POLLED; i++)

{

QM_PRINTF("%d:%d ", i, (unsigned int)samples_polled[i]);

}

QM_PUTS("\n\rADC example app complete");

# endif /* QUARK_D2000 */

return 0;

}

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2 Replies
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Employee
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Hi mailto:pavankumartadas1989@gmail.com pavankumartadas1989@gmail.com,

Thank you for contacting us.

So the ADC is giving different output values even though you're providing the same input on the same port? First, I'd check that the signal given from the board and the one from the external power supply are exactly the same. Could you post a picture of the output of the readings of the oscilloscope on both these signals?

We'll be waiting for your response.

Regards,

-Pablo

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Employee
16 Views

Hi mailto:pavankumartadas1989@gmail.com pavankumartadas1989@gmail.com,

Do you still need assistance with this thread? Did you check our latest suggestion?

-Sergio

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