void initAdc (ADC_t * adc) {
ADC_CalibrationValues_Load (adc);
ADC_ConvMode_and_Resolution_Config (adc, ADC_ConvMode_Unsigned, ADC_RESOLUTION_8BIT_gc);
ADC_Prescaler_Config (adc, ADC_PRESCALER_DIV16_gc); // Fadc = 250khz
ADC_Reference_Config (adc, ADC_REFSEL_INT1V_gc); // vref = internal 1v
/* Setup channel 0, 1, 2 and 3 to have single ended input and 1x gain. */
ADC_Ch_InputMode_and_Gain_Config (&(adc->CH0),
ADC_CH_INPUTMODE_SINGLEENDED_gc,
ADC_CH_GAIN_1X_gc);
ADC_Ch_InputMode_and_Gain_Config (&(adc->CH1),
ADC_CH_INPUTMODE_SINGLEENDED_gc,
ADC_CH_GAIN_1X_gc);
ADC_Ch_InputMode_and_Gain_Config (&(adc->CH2),
ADC_CH_INPUTMODE_SINGLEENDED_gc,
ADC_CH_GAIN_1X_gc);
ADC_Ch_InputMode_and_Gain_Config (&(adc->CH3),
ADC_CH_INPUTMODE_SINGLEENDED_gc,
ADC_CH_GAIN_1X_gc);
/* Enable high level sample complete interrupt for channel 3 */
ADC_Ch_Interrupts_Config (&(adc->CH0), ADC_CH_INTMODE_COMPLETE_gc, ADC_CH_INTLVL_LO_gc);
ADC_Ch_Interrupts_Config (&(adc->CH1), ADC_CH_INTMODE_COMPLETE_gc, ADC_CH_INTLVL_LO_gc);
ADC_Ch_Interrupts_Config (&(adc->CH2), ADC_CH_INTMODE_COMPLETE_gc, ADC_CH_INTLVL_LO_gc);
ADC_Ch_Interrupts_Config (&(adc->CH3), ADC_CH_INTMODE_COMPLETE_gc, ADC_CH_INTLVL_LO_gc);
PMIC.CTRL |= PMIC_HILVLEN_bm; // Enable low level interrupts
ADC_Enable (adc); // Enable ADC A with free running mode
ADC_Wait_32MHz (adc); // Wait until common mode voltage is stable
}
/* This function get the offset of the ADC
*
* This function makes an internal coupling to the same pin and calculate
* the internal offset in the ADC.
*
* \note This function only return the low byte of the 12-bit convertion,
* because the offset should never be more than +-8 LSB off.
*
* \param adc Pointer to the ADC to calculate offset from.
*
* \return Offset on the selected ADC
*/
uint8_t ADC_Offset_Get(ADC_t * adc)
{
uint8_t offset;
// Set up ADC to get offset.
ADC_ConvMode_and_Resolution_Config(adc, true, ADC_RESOLUTION_12BIT_gc);
ADC_Prescaler_Config(adc , ADC_PRESCALER_DIV8_gc);
ADC_Referance_Config(adc , ADC_REFSEL_INT1V_gc);
ADC_Ch_InputMode_and_Gain_Config(&(adc->CH0),
ADC_CH_INPUTMODE_DIFF_gc,
ADC_CH_GAIN_1X_gc);
ADC_Ch_InputMux_Config(&(adc->CH0), ADC_CH_MUXPOS_PIN0_gc, ADC_CH_MUXNEG_PIN0_gc);
// Enable ADC.
ADC_Enable(adc);
// Wait until ADC is ready.
ADC_Wait_32MHz(adc);
// Do one conversion to find offset.
ADC_Ch_Conversion_Start(&(adc->CH0));
do{
}while(!ADC_Ch_Conversion_Complete(&(adc->CH0)));
offset = ADC_ResultCh_GetLowByte(&(adc->CH0), 0x00);
// Disable ADC.
ADC_Disable(adc);
return offset;
}
uint16_t readADC(){
uint16_t ADC_result = 0;
int8_t offset;
/* Move stored calibration values to ADC B */
ADC_CalibrationValues_Load(&ADCA);
/* Set up ADC B to have signed conversion mode and 12 bit resolution. */
ADC_ConvMode_and_Resolution_Config(&ADCA, true, ADC_RESOLUTION_12BIT_gc);
// The ADC has different voltage reference options, controlled by the REFSEL bits in the
// REFCTRL register. Here the internal reference is selected
ADC_Reference_Config(&ADCA, ADC_REFSEL_VCC_gc);
// The clock into the ADC decide the maximum sample rate and the conversion time, and
// this is controlled by the PRESCALER bits in the PRESCALER register. Here, the
// Peripheral Clock is divided by 8 ( gives 250 KSPS with 2Mhz clock )
ADC_Prescaler_Config(&ADCA, ADC_PRESCALER_DIV8_gc);
// The used Virtual Channel (CH0) must be set in the correct mode
// In this task we will use single ended input, so this mode is selected
/* Setup channel 0 to have single ended input. */
ADC_Ch_InputMode_and_Gain_Config(&ADCA.CH0,
ADC_CH_INPUTMODE_DIFF_gc,
ADC_CH_GAIN_1X_gc);
// Setting up the which pins to convert.
// Note that the negative pin is internally connected to ground
ADC_Ch_InputMux_Config(&ADCA.CH0, ADC_CH_MUXPOS_PIN0_gc, ADC_CH_MUXNEG_PIN1_gc);
// Before the ADC can be used it must be enabled
ADC_Enable(&ADCA);
// Wait until the ADC is ready
ADC_Wait_32MHz(&ADCA);
// In the while(1) loop, a conversion is started on CH0 and the 8 MSB of the result is
// ouput on the LEDPORT when the conversion is done
/* Get offset value for ADC B. */
offset = ADC_Offset_Get_Unsigned(&ADCA, &(ADCA.CH0), true);
for(int i = 0; i<5; i++){
ADC_Ch_Conversion_Start(&ADCA.CH0);
while(!ADC_Ch_Conversion_Complete(&ADCA.CH0));
//ADCB.INTFLAGS = ADC_CH0IF_bm; // Clear CH0IF by writing a one to it
ADC_result += ADCA.CH0RES;// - offset;
}
return ADC_result/5;
}
//-----------------------------------------------------------------------------
// functions
//-----------------------------------------------------------------------------
void adc_init(void) {
/*
Note: port_init() must be run before this function, so that the inputs are
set correctly.
We are using both ADCs. So everything will be set up for ADCA && ADCB.
*/
// Load the production calibration data into each ADC.
// This data was taken by Atmel and is stored in the micro.
// This function takes care of the whole process for you.
ADC_CalibrationValues_Load(&ADCA);
ADC_CalibrationValues_Load(&ADCB);
// Set the mode of operation for each ADC
// Signed operation mode is required for the differential configuration.
ADC_ConvMode_and_Resolution_Config(&ADCA,signed_y,ADC_RESOLUTION_12BIT_gc);
ADC_ConvMode_and_Resolution_Config(&ADCB,signed_y,ADC_RESOLUTION_12BIT_gc);
// Set ADC clocks
// 32MHz / 128 = 250KHz
// I currently have no explanation for this choice
// Atmel documentation states that you need to stay within the recommended
// ADC frequencies, but I cannot find the specific numbers.
ADC_Prescaler_Config(&ADCA, ADC_PRESCALER_DIV128_gc);
ADC_Prescaler_Config(&ADCB, ADC_PRESCALER_DIV128_gc);
// Select reference to be external reference on PIN0 for A and B
ADC_Reference_Config(&ADCA, ADC_REFSEL_AREFA_gc);
ADC_Reference_Config(&ADCB, ADC_REFSEL_AREFB_gc);
// Setup all channels to have differential input and 1X gain
ADC_Ch_InputMode_and_Gain_Config(&ADCA.CH0,ADC_CH_INPUTMODE_DIFF_gc,
ADC_CH_GAIN_1X_gc); // V1
ADC_Ch_InputMode_and_Gain_Config(&ADCA.CH1,ADC_CH_INPUTMODE_DIFF_gc,
ADC_CH_GAIN_1X_gc); // V2
ADC_Ch_InputMode_and_Gain_Config(&ADCA.CH2,ADC_CH_INPUTMODE_DIFF_gc,
ADC_CH_GAIN_1X_gc); // reference
ADC_Ch_InputMode_and_Gain_Config(&ADCB.CH0,ADC_CH_INPUTMODE_DIFF_gc,
ADC_CH_GAIN_1X_gc); // I1
ADC_Ch_InputMode_and_Gain_Config(&ADCB.CH1,ADC_CH_INPUTMODE_DIFF_gc,
ADC_CH_GAIN_1X_gc); // I2
ADC_Ch_InputMode_and_Gain_Config(&ADCB.CH2,ADC_CH_INPUTMODE_DIFF_gc,
ADC_CH_GAIN_1X_gc); // reference
// Select the input pins for each ADC.
/*
See AnodV2.1.sch eagle file:
V1 - A1
V2 - A2
I1 - B1
I2 - B2
Ref - A0,A3,B0,B3
*/
ADC_Ch_InputMux_Config(&ADCA.CH0, ADC_CH_MUXPOS_PIN1_gc, \
ADC_CH_MUXNEG_PIN3_gc); // V1
ADC_Ch_InputMux_Config(&ADCA.CH1, ADC_CH_MUXPOS_PIN2_gc, \
ADC_CH_MUXNEG_PIN3_gc); // V2
ADC_Ch_InputMux_Config(&ADCA.CH2, ADC_CH_MUXPOS_PIN3_gc, \
ADC_CH_MUXNEG_PIN3_gc); // Offset calib
ADC_Ch_InputMux_Config(&ADCB.CH0, ADC_CH_MUXPOS_PIN1_gc, \
ADC_CH_MUXNEG_PIN3_gc); // V1
ADC_Ch_InputMux_Config(&ADCB.CH1, ADC_CH_MUXPOS_PIN2_gc,
ADC_CH_MUXNEG_PIN3_gc); // V2
ADC_Ch_InputMux_Config(&ADCB.CH2, ADC_CH_MUXPOS_PIN3_gc,
ADC_CH_MUXNEG_PIN3_gc); // Offset calib
// Configure the ADCA.CH2 interrupt.
// This will trip once a reading on channel 2 has been completely resolved.
// I am assuming the chan 0 and 1 of both ADCs will have their results completed
// when chan 2 is done. This is based from the Xmega A manual (sect 25)
ADC_Ch_Interrupts_Config(&ADCA.CH1, ADC_CH_INTMODE_COMPLETE_gc, \
ADC_CH_INTLVL_LO_gc);
//Enable ADCs
ADC_Enable(&ADCA);
ADC_Enable(&ADCB);
// Wait until common mode voltage is stable so tha bypass transients are not passed.
// What is the difference between the 32 and 8 MHz versions,
// and which one do I want?
ADC_Wait_32MHz(&ADCA);
ADC_Wait_32MHz(&ADCB);
// The TCD0 timer will periodically trigger an event that will create an event
// on channel 0. (Xmega A manual sect 6)
eflags.setEventSource = EVSYS_SetEventSource(0, EVSYS_CHMUX_TCD0_OVF_gc);
TC0_ConfigClockSource(&TCD0, TC_CLKSEL_DIV8_gc);
TCD0.PER = 200; // 1/f = 1/(32MHz/DIVx/PER) --- 200---50us---20KHz
// This is moved to the adc_test() fun. May want to enable it here later.
// enable timer overflow int and set priority to low.
//TCD0.INTCTRLA = TC_OVFINTLVL_LO_gc;
// An event on eventChan 0 will trigger a sweep of chan 0,1 in ADCA && ADCB.
// I do not know what would happen if an event happened on eventChan 1,2,3.
ADC_Events_Config(&ADCA, ADC_EVSEL_0123_gc, ADC_EVACT_SWEEP_gc);
ADC_Events_Config(&ADCB, ADC_EVSEL_0123_gc, ADC_EVACT_SWEEP_gc);
ADC_SweepChannels_Config(&ADCA, ADC_SWEEP_01_gc);
ADC_SweepChannels_Config(&ADCB, ADC_SWEEP_01_gc);
// Calibration routine for the ADCs
// Find offset with two pins shorted together.
// Steve also found the offset for the current with 0 current flowing into them,
// but did not do an equivalent for voltage. I will leave this out for now.
offset_A = ADC_Offset_Get_Signed(&ADCA, &(ADCA.CH2), true);
offset_B = ADC_Offset_Get_Signed(&ADCB, &(ADCB.CH2), true);
}
