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How To: Analog/Digital Converter

Analog to digital converter can measure the voltage on one of the six inputs A0 to A5 and return the measured value. The result can be a 16-bit value or float number in volts.

References​

Sampling Types​

Each channel can be configured to a different resolution and oversampling.

No matter what resolution you choose (6, 8, 10, 12) the result is always scaled to a 16-bit value of 0-65535. In asynchronous mode, you can also get the value directly in volts in the float data type.

Sampling can be synchronous and asynchronous.

Synchronous Sampling​

info

During the synchronous measurement, the code is blocked until the measurement is over.

Synchronous Sampling Code Example

#include <application.h>

void application_init(void)
{
    twr_log_init(TWR_LOG_LEVEL_DEBUG, TWR_LOG_TIMESTAMP_OFF);

    twr_adc_init();
}

void application_task()
{
    uint16_t adc;

    twr_adc_get_value(TWR_ADC_CHANNEL_A2, &adc);
    twr_log_debug("%d", adc);

    twr_scheduler_plan_current_relative(200);
}

Asynchronous Sampling​

info

Asynchronous sampling is not blocked and is running in the background.

When the result is ready, your callback function is called. It is possible to start multiple channels, the scheduler samples each channel and calls the callback for each channel separately.

Asynchronous Sampling Code Example

#include <application.h>

static void _adc_event_handler(twr_adc_channel_t channel, twr_adc_event_t event, void *param)
{
    (void) channel;
    (void) param;

    if (event == TWR_ADC_EVENT_DONE)
    {
        uint16_t adc;
        twr_adc_async_get_value(TWR_ADC_CHANNEL_A2, &adc);
        twr_log_debug("%d", adc);

        float voltage;
        twr_adc_get_result_voltage(TWR_ADC_CHANNEL_A2, &voltage);
        twr_log_debug("%f", voltage);
    }
}

void application_init(void)
{
    twr_log_init(TWR_LOG_LEVEL_DEBUG, TWR_LOG_TIMESTAMP_OFF);

    twr_adc_init();
    twr_adc_set_event_handler(TWR_ADC_CHANNEL_A2, _adc_event_handler, NULL);
    twr_adc_resolution_set(TWR_ADC_CHANNEL_A2, TWR_ADC_RESOLUTION_12_BIT);
    twr_adc_oversampling_set(TWR_ADC_CHANNEL_A2, TWR_ADC_OVERSAMPLING_256);
}

void application_task()
{
    twr_adc_async_measure(TWR_ADC_CHANNEL_A2);

    twr_scheduler_plan_current_relative(200);
}