/**
* \brief Initialize ADC
*
* Here the averaging feature is disabled.
*/
static void main_adc_init(void)
{
/* ADC module configuration structure */
struct adc_config adc_conf;
/* ADC channel configuration structure */
struct adc_channel_config adcch_conf;
/* Configure the ADC module:
* - unsigned, more than 12-bit results
* - VCC /2 voltage reference
* - 200 kHz maximum clock rate
* - freerun conversion triggering
* - enabled internal temperature sensor
*/
adc_read_configuration(&ADCA, &adc_conf);
adc_set_conversion_parameters(&adc_conf, ADC_SIGN_OFF, ADC_RES_12,
ADC_REF_VCCDIV2);
adc_set_clock_rate(&adc_conf, 200000UL);
adc_set_conversion_trigger(&adc_conf, ADC_TRIG_FREERUN, 1, 0);
adc_enable_internal_input(&adc_conf, ADC_INT_TEMPSENSE);
adc_write_configuration(&ADCA, &adc_conf);
/* Configure ADC channel 0:
* - single-ended measurement from temperature sensor
* - interrupt flag set on completed conversion
*/
adcch_read_configuration(&ADCA, ADC_CH0, &adcch_conf);
adcch_set_input(&adcch_conf, ADCCH_POS_TEMPSENSE, ADCCH_NEG_NONE, 1);
adcch_set_interrupt_mode(&adcch_conf, ADCCH_MODE_COMPLETE);
adcch_disable_interrupt(&adcch_conf);
adcch_write_configuration(&ADCA, ADC_CH0, &adcch_conf);
/* Enable ADC which starts the freerun conversion.*/
adc_enable(&ADCA);
}
/**
* \brief Callback function for ADCB-CH0 interrupts
* - Interrupt is configured for Conversion Complete Interrupt
* - ADCA CH0 result is accumulated
* - ADC sample count is incremented
* - Check If ADC sample count reached up to number of oversampling required
* - If so, disable ADC interrupt and set flag to start oversampling process
*
* \param adc Pointer to ADC module.
* \param ch_mask ADC channel mask.
* \param result Conversion result from ADC channel.
*/
static void adc_handler(ADC_t *adc, uint8_t ch_mask, adc_result_t result)
{
/* Get Result from ADCB-CH0 Register and Accumulate */
adc_result_accumulator += result;
/* Increment sample count */
adc_samplecount++;
/* Check if sample count has reached oversample count */
if (adc_samplecount >= ADC_OVER_SAMPLED_NUMBER) {
/* Disable ADCB-CHO conversion complete interrupt until stored
* samples are processed
*/
adcch_disable_interrupt(&adc_ch_conf);
adcch_write_configuration(&ADCB, ADC_CH0, &adc_ch_conf);
/* Clear any pending interrupt request by clearing interrupt
* flag
*/
adc_clear_interrupt_flag(&ADCB, ADC_CH0);
/*Set adc_oversampled_flag to start oversampling process from
* main function
*/
adc_oversampled_flag = true;
/* Store single sample ADC result to find analog input without
* oversampling
*/
adc_result_one_sample = result;
}
}
/**
* \brief Callback function that changes ADC settings
*
* This callback function for the ADC driver is used to change the ADC reference
* after the next completed conversion, simulating a problem with the voltage
* reference. It will be triggered after the next completed conversion.
*
* The fault will be detected when the analog IO test is run, i.e., when the
* user turns up the power of the plate from 0.
*/
static void adc_foul_callback(ADC_t *adc, uint8_t ch_mask, adc_result_t res)
{
struct adc_channel_config adcch_conf;
adc->REFCTRL = ADC_REFSEL_INTVCC_gc;
adcch_read_configuration(adc, ch_mask, &adcch_conf);
adcch_disable_interrupt(&adcch_conf);
adcch_write_configuration(adc, ch_mask, &adcch_conf);
}
/**
* \brief Initialize ADC
*/
static void main_adc_init(void)
{
/* ADC module configuration structure */
struct adc_config adc_conf;
/* ADC channel configuration structure */
struct adc_channel_config adcch_conf;
/* Configure the ADC module:
* - signed, 12-bit results
* - voltage reference = VCC / 1.6 = 3.3V / 1.6
* - 200 kHz maximum clock rate
* - manual conversion triggering
*/
adc_read_configuration(&ADCA, &adc_conf); /* Initialize structures. */
adc_set_conversion_parameters(&adc_conf, ADC_SIGN_ON, ADC_RES_12,
ADC_REF_VCC);
adc_set_clock_rate(&adc_conf, 200000UL);
adc_set_conversion_trigger(&adc_conf, ADC_TRIG_MANUAL, 1, 0);
adc_write_configuration(&ADCA, &adc_conf);
/* Configure ADC channel:
* - differential measurement mode
* - Input voltage V+ is ADC2 pin (PA2 pin)
* - Input voltage V- is ADC3 pin (PA3 pin)
* - 1x gain
* - interrupt flag set on completed conversion
*/
adcch_read_configuration(&ADCA, ADC_CH0, &adcch_conf);
adcch_set_input(&adcch_conf, ADCCH_POS_PIN2, ADCCH_NEG_PIN3, 1);
adcch_set_interrupt_mode(&adcch_conf, ADCCH_MODE_COMPLETE);
adcch_disable_interrupt(&adcch_conf);
adcch_write_configuration(&ADCA, ADC_CH0, &adcch_conf);
/* Enable ADC */
adc_enable(&ADCA);
/* Do useful conversion */
adc_start_conversion(&ADCA, ADC_CH0);
adc_wait_for_interrupt_flag(&ADCA, ADC_CH0);
}
/**
* \internal
* \brief Measure differential input MUX combinations on channel
*
* Measures a set of input MUX combinations on a single channel, using averaging
* of the number of samples specified with \ref NUM_AVERAGE_SAMPLES.
*
* \pre This function does not configure the ADC, only the ADC channel, and
* therefore the specified ADC needs to be configured before this function
* is run.
*
* \param adc Pointer to ADC to measure with.
* \param ch_mask Mask for channel to measure with.
* \param mux_pos_inputs Pointer to array of positive input MUX settings.
* \param mux_neg_inputs Pointer to array of negative input MUX settings.
* \param num_inputs Number of input MUX setting pairs.
* \param results Pointer to array to store results in.
* \param gain Gain to use for all measurements.
*
* \note The array which \e results points to must have at least \e num_inputs
* elements.
*/
static void differential_signed_average(ADC_t *adc, uint8_t ch_mask,
const uint8_t *mux_pos_inputs, const uint8_t *mux_neg_inputs,
uint8_t num_inputs, int16_t *results, uint8_t gain)
{
struct adc_channel_config adcch_conf;
uint8_t input;
uint8_t i;
int32_t sum;
memset(&adcch_conf, 0, sizeof(struct adc_channel_config));
// Common configuration
adcch_set_interrupt_mode(&adcch_conf, ADCCH_MODE_COMPLETE);
adcch_disable_interrupt(&adcch_conf);
for (input = 0; input < num_inputs; input++) {
adcch_set_input(&adcch_conf, mux_pos_inputs[input],
mux_neg_inputs[input], gain);
adcch_write_configuration(adc, ch_mask, &adcch_conf);
// Enable and do dummy conversion
adc_enable(adc);
adc_start_conversion(adc, ch_mask);
adc_wait_for_interrupt_flag(adc, ch_mask);
// Read an average
sum = 0;
for (i = 0; i < NUM_AVERAGE_SAMPLES; i++) {
adc_start_conversion(adc, ch_mask);
adc_wait_for_interrupt_flag(adc, ch_mask);
sum += (int16_t)adc_get_result(adc, ch_mask);
}
adc_disable(adc);
results[input] = sum / NUM_AVERAGE_SAMPLES;
}
}
int main(void)
{
struct adc_config adc_conf;
struct adc_channel_config adcch_conf;
board_init();
sysclk_init();
sleepmgr_init();
irq_initialize_vectors();
cpu_irq_enable();
// Initialize configuration structures.
adc_read_configuration(&ADCA, &adc_conf);
adcch_read_configuration(&ADCA, ADC_CH0, &adcch_conf);
/* Configure the ADC module:
* - unsigned, 12-bit results
* - bandgap (1 V) voltage reference
* - 200 kHz maximum clock rate
* - manual conversion triggering
*/
adc_set_conversion_parameters(&adc_conf, ADC_SIGN_OFF, ADC_RES_12,
ADC_REF_BANDGAP);
adc_set_clock_rate(&adc_conf, 200000UL);
adc_set_conversion_trigger(&adc_conf, ADC_TRIG_MANUAL, 1, 0);
adc_write_configuration(&ADCA, &adc_conf);
/* Configure ADC channel 0:
* - single-ended measurement from configured input pin
* - interrupt flag set on completed conversion
*/
adcch_set_input(&adcch_conf, INPUT_PIN, ADCCH_NEG_NONE,
1);
adcch_set_interrupt_mode(&adcch_conf, ADCCH_MODE_COMPLETE);
adcch_disable_interrupt(&adcch_conf);
adcch_write_configuration(&ADCA, ADC_CH0, &adcch_conf);
// Enable the ADC and do one dummy conversion.
adc_enable(&ADCA);
adc_start_conversion(&ADCA, ADC_CH0);
adc_wait_for_interrupt_flag(&ADCA, ADC_CH0);
// Light up LED 1, wait for button press.
ioport_set_pin_low(LED1_PIN);
wait_for_button();
// Perform oversampling of offset.
cal_data.offset = get_mean_sample_value();
// Light up LED 2, wait for button press.
ioport_set_pin_low(LED2_PIN);
wait_for_button();
// Perform oversampling of 0.9 V for gain calibration.
cal_data.gain = get_mean_sample_value() - cal_data.offset;
// Turn off LEDs.
ioport_set_pin_high(LED1_PIN);
ioport_set_pin_high(LED2_PIN);
// Enable interrupts on ADC channel, then trigger first conversion.
adcch_enable_interrupt(&adcch_conf);
adcch_write_configuration(&ADCA, ADC_CH0, &adcch_conf);
adc_start_conversion(&ADCA, ADC_CH0);
do {
// Sleep until ADC interrupt triggers.
sleepmgr_enter_sleep();
} while (1);
}