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Multichannel use of ADC in NRF51822

I want to measure voltages at all 8 channels but when I am enabling all channels its sending the values once only and after that its not sending anything, my requirement is i don't want to use any handler,i am using polling method simultaneously to sample ADC,please suggest if any code available or any support message for the same.

Parents
  • Yes I want to sample all 8 channels, continuously without using  handler,I want to prefer sampleconvert() func because there is need afterwards, ii am not using any timer and don't want use it. I just want to sample all ADC pins continuously.

  • Akshay Khairkar said:
    Yes I want to sample all 8 channels, continuously without using  handler,I want to prefer sampleconvert() func because there is need afterwards, ii am not using any timer and don't want use it. I just want to sample all ADC pins continuously.

    This means that you will have to reconfigure for every channel, and call the sample function in a loop.
    Which SDK version are you using?

    I understand that you do not want to use a handler or a timer, but is there a particular reason for this? Your general application performance might be considerably worse if you do nothing to time or otherwise control when and how fast the samplings happen - but you are of course free to do so.

    Best regards,
    Karl

  • I have BLE 400 Waveshare board i am connecting to AN0 pin and AN1 pin and giving 3.3v on that and also for checking connecting it to ground using 10 bit ADC which can give o/p as 2^10 i.e. upto 1024 certainly with or without i/p its giving same value, there is no formula i am using right now i just want some o/p but its giving the o/p as mentioned above queries.

  • Please verify that you are using the correct pins on the Waveshare board. Could you share with me the pinout of the waveshare board you are using, and how you are testing it?

    Akshay Khairkar said:
    i am connecting to AN0 pin and AN1 pin

    I assume you then have changed the code I provided earlier, to reflect this?
    Please share with me the code you are currently running.

    Akshay Khairkar said:
    10 bit ADC which can give o/p as 2^10 i.e. upto 1024 certainly with or without i/p its giving same value, there is no formula i am using right now i just want some o/p but its giving the o/p as mentioned above queries.

    I do not know what you mean by "o/p", but I agree that reading values in the 500 range using the 10-bit ADC configuration sounds strange.

    Best regards,
    Karl

  • Output (O/p) is nothing but value i am getting after reading ADC, I just want ADC to give me some values according to my input to AN0 or AN1 pin still i am not getting any values.Please suggest me if any other ways if available to read multichannel ADC values or tell me if it is hardware restriction

  • Akshay Khairkar said:
    value i am getting after reading ADC, I just want ADC to give me some values according to my input to AN0 or AN1 pin still i am not getting any values

    You are not giving me a lot to work with here, since you are not answering my questions.
    Please, take a look at what I asked about in my previous reply, and answer the questions I wrote you.
    I require more information in order to help you resolve this issue.

    Akshay Khairkar said:
    or tell me if it is hardware restriction

    I assure you there are no hardware restrictions on reading multiple channels of the ADC. Do not worry, the issue here is not hardware restrictions.

    Best regards,
    Karl

  • static nrf_drv_adc_channel_t m_channel_config_0 = NRF_DRV_ADC_DEFAULT_CHANNEL(NRF_ADC_CONFIG_INPUT_0);
    static nrf_drv_adc_channel_t m_channel_config_1 = NRF_DRV_ADC_DEFAULT_CHANNEL(NRF_ADC_CONFIG_INPUT_1);
    
    static  nrf_adc_value_t sample_channel_0 = 0;
    static  nrf_adc_value_t sample_channel_1 = 0;
    
    static void adc_init(void)
    {
        ret_code_t err_code;
        nrf_drv_adc_config_t config = NRF_DRV_ADC_DEFAULT_CONFIG;
        
        err_code = nrf_drv_adc_init(&config, NULL);
        APP_ERROR_CHECK(err_code);
    }
    
    //Error Code:H1600
    void user_adc_init0(){
             nrf_drv_adc_sample_convert(&m_channel_config_0, &sample_channel_0);
      
             nrf_delay_ms(1000);
    
             printf("\r\n  0 :%d\r\n",sample_channel_0);
       
    }
    //Error Code:H1700
    void user_adc_init1(){
       
       
          nrf_drv_adc_sample_convert(&m_channel_config_1, &sample_channel_1);
       
            printf("\r\n  1 : %d\r\n",sample_channel_1);
    }
    int main(void)
    {
    
    adc_init();
    for (;;)
        {
          printf("\r\n for Start!\r\n");
          user_adc_init0();
          nrf_delay_ms(100);
          user_adc_init1();
          nrf_delay_ms(100);
          nrf_delay_ms(2000);
          printf("\r\nADC fin!\r\n");
          
          printf("\r\n  0 :%d\r\n",sample_channel_0);
          printf("\r\n  1 : %d\r\n",sample_channel_1);
          
         }
    }
    
    

Reply
  • static nrf_drv_adc_channel_t m_channel_config_0 = NRF_DRV_ADC_DEFAULT_CHANNEL(NRF_ADC_CONFIG_INPUT_0);
    static nrf_drv_adc_channel_t m_channel_config_1 = NRF_DRV_ADC_DEFAULT_CHANNEL(NRF_ADC_CONFIG_INPUT_1);
    
    static  nrf_adc_value_t sample_channel_0 = 0;
    static  nrf_adc_value_t sample_channel_1 = 0;
    
    static void adc_init(void)
    {
        ret_code_t err_code;
        nrf_drv_adc_config_t config = NRF_DRV_ADC_DEFAULT_CONFIG;
        
        err_code = nrf_drv_adc_init(&config, NULL);
        APP_ERROR_CHECK(err_code);
    }
    
    //Error Code:H1600
    void user_adc_init0(){
             nrf_drv_adc_sample_convert(&m_channel_config_0, &sample_channel_0);
      
             nrf_delay_ms(1000);
    
             printf("\r\n  0 :%d\r\n",sample_channel_0);
       
    }
    //Error Code:H1700
    void user_adc_init1(){
       
       
          nrf_drv_adc_sample_convert(&m_channel_config_1, &sample_channel_1);
       
            printf("\r\n  1 : %d\r\n",sample_channel_1);
    }
    int main(void)
    {
    
    adc_init();
    for (;;)
        {
          printf("\r\n for Start!\r\n");
          user_adc_init0();
          nrf_delay_ms(100);
          user_adc_init1();
          nrf_delay_ms(100);
          nrf_delay_ms(2000);
          printf("\r\nADC fin!\r\n");
          
          printf("\r\n  0 :%d\r\n",sample_channel_0);
          printf("\r\n  1 : %d\r\n",sample_channel_1);
          
         }
    }
    
    

Children
  • So here is my code for sampling 2 ADC channels and just printing the values of ADC, i just want ADC to give me values in printf statement according to the i/p like if i am giving  some voltages over this maybe between 1.0V to 3.3v so i should get the values according to voltage i.e.in between 0 - 1024 , but the values  i am getting are not changing i.e with or without input i am getting same values.

  • Akshay Khairkar said:
    i.e with or without input i am getting same values.

    And what values are these? What is this program outputting? You need to tell me what is happening.
    You need to give me all the available information, so that I may best help you.

    I see from your code that you have changed the sample_channel_* variable types from static volatile in the code I provided you earlier. Why have you done this?
    If they are not declared as volatile then the compiler will optimize them to a constant value of 0.

    By omitting such details, or making changes without telling me, you are making it very hard to help you.

    In the future, please write out your problem description, symptoms and goals as clearly as possible in order for others to be able to help you.
    This will reduce the time it takes for you to receive help, and the time it takes to give this help.

    Please try to change the samples' type back to static volatile, and let me know what you observe when running the program.

    Best regards,
    Karl

  • Values i am getting 528 or 536 in printf statement as already told to you in the conversation.

    Yeah, in future i will do so I thought that was sufficient to be understandable.

    If i am making it volatile compiler giving me error which is as below

    error: passing argument 2 of 'nrf_drv_adc_sample_convert' discards 'volatile' qualifier from pointer target type [-Werror=discarded-qualifiers]
    644 | nrf_drv_adc_sample_convert(&m_channel_config_0, &sample_channel_0);
    | ^~~~~~~~~~~~~~~~~
    In file included from main.c:68:
    components/drivers_nrf/adc/nrf_drv_adc.h:234:57: note: expected 'nrf_adc_value_t *' {aka 'short int *'} but argument is of type 'volatile nrf_adc_value_t *' {aka 'volatile short int *'}
    234 | nrf_adc_value_t * p_value);
    | ~~~~~~~~~~~~~~~~~~^~~~~~~
    cc1: all warnings being treated as errors
    make: *** [components/toolchain/gcc/Makefile.common:135: _build/nrf51422_xxac_main.c.o] Error 1

    I am using visual studio for programming

  • Akshay Khairkar said:
    Values i am getting 528 or 536 in printf statement as already told to you in the conversation.

    Thank you for clarifying, this is hard for me to know when you are not being specific and saying things like "not getting any values".

    I would not expect values in the 500 range when the pins are connected to either ground or VDD, I therefore suspect that these pins either is used for something else on the waveboard, or that you are connecting the wrong pins.

    Could you please share the datasheet and pinout of the waveboard device you are working with?
    Please also specify exactly which pins you are using on the board - do not say AIN0 and AIN1, unless they are marked as such on the board itself.

    Akshay Khairkar said:
    Yeah, in future i will do so I thought that was sufficient to be understandable.

    Thank you, I appreciate it.

    Looking forward to resolving this issue together,

    Best regards,
    Karl

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