2.8.2.1.3 Workflow

Create a module software instance structure for the ADC module to store the ADC driver state while in use.
```
struct adc_module adc_instance;
```
Note: This should never go out of scope as long as the module is in use. In most cases, this should be global.
Create a buffer for the ADC samples to be stored in by the driver asynchronously.
```
#define ADC_SAMPLES 128
uint16_t adc_result_buffer[ADC_SAMPLES];
```

Create a callback function that will be called each time the ADC completes an asynchronous read job.

volatile bool adc_read_done = false;

void adc_complete_callback(
        struct adc_module *const module)
{
    adc_read_done = true;
}

Configure the ADC module.

Create an ADC module configuration struct, which can be filled out to adjust the configuration of a physical ADC peripheral.
```
struct adc_config config_adc;
```
Initialize the ADC configuration struct with the module's default values.
```
adc_get_config_defaults(&config_adc);
```
Note: This should always be performed before using the configuration struct to ensure that all values are initialized to known default settings.

Change the ADC module configuration to suit the application.

#if (!SAML21) && (!SAML22) && (!SAMC21)
    config_adc.gain_factor     = ADC_GAIN_FACTOR_DIV2;
#endif
    config_adc.clock_prescaler = ADC_CLOCK_PRESCALER_DIV8;
    config_adc.reference       = ADC_REFERENCE_INTVCC1;
#if (SAMC21)
    config_adc.positive_input  = ADC_POSITIVE_INPUT_PIN5;
#else
    config_adc.positive_input  = ADC_POSITIVE_INPUT_PIN6;
#endif
    config_adc.resolution      = ADC_RESOLUTION_12BIT;

Set ADC configurations.

#if (SAMC21)
    adc_init(&adc_instance, ADC1, &config_adc);
#else
    adc_init(&adc_instance, ADC, &config_adc);
#endif

Enable the ADC module so that conversions can be made.
```
adc_enable(&adc_instance);
```

Register and enable the ADC Read Buffer Complete callback handler.
1. Register the user-provided Read Buffer Complete callback function with the driver, so that it will be run when an asynchronous buffer read job completes.
```
adc_register_callback(&adc_instance,
        adc_complete_callback, ADC_CALLBACK_READ_BUFFER);
```
2. Enable the Read Buffer Complete callback so that it will generate callbacks.
```
adc_enable_callback(&adc_instance, ADC_CALLBACK_READ_BUFFER);
```

SMART ARM-based Microcontrollers

2.8.2.1.3 Workflow