/** * \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); }