How to configure ADC in single end mode and also how to control my samplerate using local timer?

[vishal]

Hello, I am using nRF52832 DK, and implement my software using eclipse with ARM GCC complier sdk12.1. I have interface accelerometer sensor with this board. I have read SAADC and send adc value to android apps. I am using 12 bit ADC, But problem is for calibrating acceleration analog value. So I want to use single ended mode for ADC and how to select mode for control the sample rate using CC. I read data sheet for controlling sample rate, but unable to understand what's I need to change in my program. nRF52832 data sheet is in given like this (Capture and compare value. Sample rate is 16 MHz/CC). So please help me for how to configure my program with above changes let me know., or can you give me some reference link tutorial.......

Thanks in Advanced......

[vishal]

Thank you sir for giving me reply. let me explain what actually I have faing problem. I have using ADXL335 accelerometer sensor and I have successfully read three axis X Y Z by 12 bit SAADC and also send this to BLE. Actual sensor data is coming but sir I need to increase sampling rate upto 24575 point for each analog channel. my ADC is in scan mode I have use only three channel for X y and z axis. When I increase sampling rate and covert to micro second BLE is not connect with my apps. Please sir how to solved this problem. and one if the another problem is I am not able to send 12 bit value for the range of 0-4095. Its only 8 bit data send not see properly my three axis value. Please tell me sir how to convert uint_8 array into uint16_t bit array. I am search lots of tutorial and community it said it say like this --> value[i2] = adc_value; value[(i2)+1] = adc_value >> 8; why need to right shift by 8 bit. for sending data data over ble. please sir let me know. And I know your support is very good and quick response with question.. My ADC code is

void saadc_sampling_event_enable(void)
{
    ret_code_t err_code = nrf_drv_ppi_channel_enable(m_ppi_channel);
    APP_ERROR_CHECK(err_code);
}

void saadc_callback(nrf_drv_saadc_evt_t const * p_event)
{
    if (p_event->type == NRF_DRV_SAADC_EVT_DONE)
    {
        ret_code_t err_code;
        uint16_t adc_value;
      //  uint16_t value1[SAADC_SAMPLES_IN_BUFFER*2];
        uint8_t value[SAADC_SAMPLES_IN_BUFFER*2]; // own change uint8_t
        uint8_t bytes_to_send;
//        uint16_t data[3];
     
        // set buffers
        err_code = nrf_drv_saadc_buffer_convert(p_event->data.done.p_buffer, SAADC_SAMPLES_IN_BUFFER);
        APP_ERROR_CHECK(err_code);

        // print samples on hardware UART and parse data for BLE transmission
        printf("ADC event number: %d\r\n",(int)m_adc_evt_counter);
        for (int i = 0; i < SAADC_SAMPLES_IN_BUFFER; i++)
        {
            printf("%d\r\n", p_event->data.done.p_buffer[i]);
             adc_value = p_event->data.done.p_buffer[i];
//             for (int j = 0; j <24576; j++)
//             {
//            	 data = adc_value;
//             }
//            adc_value = 4095;
            value[i*2] = adc_value;
            value[(i*2)+1] = adc_value >> 8;

        }
				
        // Send data over BLE via NUS service. Makes sure not to send more than 20 bytes.
        if((SAADC_SAMPLES_IN_BUFFER*2) <= 20)
        {
            bytes_to_send = (SAADC_SAMPLES_IN_BUFFER*2);
        }
        else 
        {
            bytes_to_send = 20;
        }


        err_code = ble_nus_string_send(&m_nus, value, bytes_to_send);
        if (err_code != NRF_ERROR_INVALID_STATE) 
        {
            APP_ERROR_CHECK(err_code);
        }
						
        m_adc_evt_counter++;
    }
}

void saadc_init(void)
{
    ret_code_t err_code;
	
    nrf_drv_saadc_config_t saadc_config = NRF_DRV_SAADC_DEFAULT_CONFIG;
    saadc_config.resolution = NRF_SAADC_RESOLUTION_12BIT;
	
    nrf_saadc_channel_config_t channel_0_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN4);
    channel_0_config.gain = NRF_SAADC_GAIN1_4;
    channel_0_config.reference = NRF_SAADC_REFERENCE_VDD4;
	
    nrf_saadc_channel_config_t channel_1_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN5);
    channel_1_config.gain = NRF_SAADC_GAIN1_4;
    channel_1_config.reference = NRF_SAADC_REFERENCE_VDD4;

    nrf_saadc_channel_config_t channel_2_config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN6);
    channel_2_config.gain = NRF_SAADC_GAIN1_4;
    channel_2_config.reference = NRF_SAADC_REFERENCE_VDD4;
	
//    nrf_saadc_channel_config_t channel_3_config =
//        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN7);
//    channel_3_config.gain = NRF_SAADC_GAIN1_4;
//    channel_3_config.reference = NRF_SAADC_REFERENCE_VDD4;

    err_code = nrf_drv_saadc_init(&saadc_config, saadc_callback);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_channel_init(0, &channel_0_config);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_saadc_channel_init(1, &channel_1_config);
    APP_ERROR_CHECK(err_code);
    err_code = nrf_drv_saadc_channel_init(2, &channel_2_config);
    APP_ERROR_CHECK(err_code);
//    err_code = nrf_drv_saadc_channel_init(3, &channel_3_config);
//    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[0],SAADC_SAMPLES_IN_BUFFER);
    APP_ERROR_CHECK(err_code);   
    err_code = nrf_drv_saadc_buffer_convert(m_buffer_pool[1],SAADC_SAMPLES_IN_BUFFER);
    APP_ERROR_CHECK(err_code);
}