PSoC™ 4 Forum Discussions

Hello all,

I got a problem with ADC. Here is what I want to do. I want to measure voltage on 4 channels (use differential mode, not single-ended). I want to measure an average value from ADC input based on 10000 samples. I also want to do this inside interrupt - but when I try it all cruches..

Inside ADC_SAR_Seq_1_INT.c I got something like this:

/*******************************************************************************
* File Name: ADC_SAR_Seq_1_INT.c
* Version 2.40
*
*  Description:
*    This file contains the code that operates during the ADC_SAR interrupt
*    service routine.
*
*   Note:
*
********************************************************************************
* Copyright 2008-2015, Cypress Semiconductor Corporation.  All rights reserved.
* You may use this file only in accordance with the license, terms, conditions,
* disclaimers, and limitations in the end user license agreement accompanying
* the software package with which this file was provided.
*******************************************************************************/

#include "ADC_SAR_Seq_1.h"
#include "cyapicallbacks.h"


/******************************************************************************
* Custom Declarations and Variables
* - add user inlcude files, prototypes and variables between the following
*   #START and #END tags
******************************************************************************/
/* `#START ADC_SYS_VAR`  */

#define "adc.h"

extern int16 dataReady;

extern int16 result_0;
extern int16 result_1;
extern int16 result_2;
extern int16 result_3;

/* `#END`  */

#if(ADC_SAR_Seq_1_IRQ_REMOVE == 0u)


    /******************************************************************************
    * Function Name: ADC_SAR_Seq_1_ISR
    *******************************************************************************
    *
    * Summary:
    *  Handle Interrupt Service Routine.
    *
    * Parameters:
    *  None.
    *
    * Return:
    *  None.
    *
    * Reentrant:
    *  No.
    *
    ******************************************************************************/
    CY_ISR( ADC_SAR_Seq_1_ISR )
    {
        uint32 intr_status;

        /* Read interrupt status register */
        intr_status = ADC_SAR_Seq_1_SAR_INTR_REG;

        #ifdef ADC_SAR_Seq_1_ISR_INTERRUPT_CALLBACK
            ADC_SAR_Seq_1_ISR_InterruptCallback();
        #endif /* ADC_SAR_Seq_1_ISR_INTERRUPT_CALLBACK */


        /************************************************************************
        *  Custom Code
        *  - add user ISR code between the following #START and #END tags
        *************************************************************************/
        /* `#START MAIN_ADC_ISR`  */
        
        result_0 = GetADCValue(0);
        result_1 = GetADCValue(1);
        result_2 = GetADCValue(2);
        result_3 = GetADCValue(3);
        //This works!
        //result_0 = ADC_SAR_Seq_1_GetResult16(0);
        //result_1 = ADC_SAR_Seq_1_GetResult16(1);
        //result_2 = ADC_SAR_Seq_1_GetResult16(2);
        //result_3 = ADC_SAR_Seq_1_GetResult16(3);

        dataReady = 1;
        
        /* `#END`  */
        
        /* Clear handled interrupt */
        ADC_SAR_Seq_1_SAR_INTR_REG = intr_status;
    }

#endif   /* End ADC_SAR_Seq_1_IRQ_REMOVE */


/* [] END OF FILE */

My function GetADCValue looks like this:

#define SAMPLES 10000

int GetADCValue(int ChanelNumber)
{
    int loopCtr = 0;
    int sum;
    float adc_0;
    float sum_0 = 0;

    for(loopCtr = 0; loopCtr < SAMPLES; ++loopCtr)
    {
        adc_0 = ADC_SAR_Seq_1_GetResult16(ChanelNumber);
        if (adc_0 > 0)
        {   
            sum_0 = sum_0 + adc_0;
        }
        else
        {
            sum_0 = sum_0 - adc_0;
        }
    }
    sum_0 = sum_0/SAMPLES;
    sum = (int)sum_0;

    return sum;
}

I think that my calculation takes too much time of processor.. I have idea to maybe read one time in interrupt value from ADC - but from which channel should I read? How can I know which channel (0, 1, 2 or 3) causes interrupt?

Here you got my setting of ADC.

ADC_SAR

In the main.c I also call my function ADCInit which looks like this:

void ADCInit(void)
{
    ADC_SAR_Seq_1_Start();
    ADC_SAR_Seq_1_IRQ_Enable();
    ADC_SAR_Seq_1_StartConvert();
}

Thank guys for help and anny suggestions! Wish all of You a Happy New Year :)!