Simultaneous implementation of AD conversion

RE: Simultaneous implementation of AD conversion

LemonCake — Wed, 19 Apr 2023 08:53:03 GMT

Thank you for your assistance.
Thank you very much for taking the time for me.
I proceeded with the coding based on the advice you gave me, and was able to successfully complete the simultaneous implementation.
Thank you very much.

RE: Simultaneous implementation of AD conversion

Jørgen Holmefjord — Tue, 18 Apr 2023 15:48:49 GMT

Hi,

You should not call nrf_drv_saadc_init() twice, with different event handlers. The driver only needs to be initialized once, unless you uninitialized the driver to stop using it at some point. Both channels will be sampled and accessible in the buffer pointed at in the common event handler, through p_evt->data.done.p_buffer[0] and p_evt->data.done.p_buffer[1].

In the code you posted, both channels are set to NRF_SAADC_INPUT_AIN5. Also make sure that adc_buf is declared with space for two SAADC samples.

Best regards,
Jørgen

RE: Simultaneous implementation of AD conversion

LemonCake — Tue, 18 Apr 2023 04:54:52 GMT

Thank you very much for your reply.
Regarding the content of the error, if you set two programs of the same type in es_battery_voltage_saadc.c as shown below and execute them in main (), both the battery voltage and the LED connection voltage will be output as 0. increase.
Thank you very much.

static void saadc_event_handler(nrf_drv_saadc_evt_t const * p_evt)
{
    if (p_evt->type == NRF_DRV_SAADC_EVT_DONE)
    {
        nrf_saadc_value_t adc_result;

        adc_result = p_evt->data.done.p_buffer[0];

        m_batt_lvl_in_milli_volts =
            ADC_RESULT_IN_MILLI_VOLTS(adc_result) + DIODE_FWD_VOLT_DROP_MILLIVOLTS;
    }
}

static void saadc_event_handler2(nrf_drv_saadc_evt_t const * p_evt)
{
    if (p_evt->type == NRF_DRV_SAADC_EVT_DONE)
    {
        nrf_saadc_value_t adc_result;

        adc_result = p_evt->data.done.p_buffer[0];

        m_batt_lvl_in_milli_volts2 =
            ADC_RESULT_IN_MILLI_VOLTS(adc_result) + DIODE_FWD_VOLT_DROP_MILLIVOLTS;
    }
}


void es_battery_voltage_init(void)
{
    ret_code_t err_code = nrf_drv_saadc_init(NULL, saadc_event_handler);

    APP_ERROR_CHECK(err_code);

    nrf_saadc_channel_config_t config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN5);
    err_code = nrf_drv_saadc_channel_init(0, &config);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_buffer_convert(&adc_buf, 2);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_sample();
    APP_ERROR_CHECK(err_code);
}


void es_battery_voltage_get(uint16_t * p_vbatt)
{
    VERIFY_PARAM_NOT_NULL_VOID(p_vbatt);

    *p_vbatt = m_batt_lvl_in_milli_volts;
    if (!nrf_drv_saadc_is_busy())
    {
        ret_code_t err_code = nrf_drv_saadc_buffer_convert(&adc_buf, 2);
        APP_ERROR_CHECK(err_code);

        err_code = nrf_drv_saadc_sample();
        APP_ERROR_CHECK(err_code);
    }
}

void led_monitor_init(void)
{
    ret_code_t err_code = nrf_drv_saadc_init(NULL, saadc_event_handler2);

    APP_ERROR_CHECK(err_code);

    nrf_saadc_channel_config_t config =
        NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_AIN5);
    err_code = nrf_drv_saadc_channel_init(1, &config);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_buffer_convert(&adc_buf, 2);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_drv_saadc_sample();
    APP_ERROR_CHECK(err_code);
}

void led_monitor_get(uint16_t * p_vbatt)
{
    VERIFY_PARAM_NOT_NULL_VOID(p_vbatt);

    *p_vbatt = m_batt_lvl_in_milli_volts2;
    if (!nrf_drv_saadc_is_busy())
    {
        ret_code_t err_code = nrf_drv_saadc_buffer_convert(&adc_buf, 2);
        APP_ERROR_CHECK(err_code);

        err_code = nrf_drv_saadc_sample();
        APP_ERROR_CHECK(err_code);
    }
}

RE: Simultaneous implementation of AD conversion

Jørgen Holmefjord — Mon, 17 Apr 2023 13:43:34 GMT

Hi,

Can you elaborate on what is not working with the code you tested?

Once you have two channels enabled at the same time, the SAADC peripheral will enter scan mode, where each enabled channel is sampled consecutively each time you trigger the sample task. The samples will be stored in the buffer as shown in the peripheral documentation. You need to increase the buffer size passed to nrf_drv_saadc_buffer_convert() if you want to have two channels enabled at the same time.

Best regards,
Jørgen