void InitADC( ADC_t *ADC_Pointer )
{
// Initialize sweep for channel 0, 1, 2 and 3
ADC_SweepChannels_Config( ADC_Pointer, ADC_SWEEP_0123_gc );
// Setup event to start synchronized sweep
ADC_Events_Config( ADC_Pointer, ADC_EVSEL_0123_gc, ADC_EVACT_SYNCHSWEEP_gc );
// Initialize the four channels to convert in single ended mode
ADC_Ch_InputMode_and_Gain_Config( &ADC_Pointer->CH0, ADC_CH_INPUTMODE_SINGLEENDED_gc, ADC_CH_GAIN_1X_gc );
ADC_Ch_InputMode_and_Gain_Config( &ADC_Pointer->CH1, ADC_CH_INPUTMODE_SINGLEENDED_gc, ADC_CH_GAIN_1X_gc );
ADC_Ch_InputMode_and_Gain_Config( &ADC_Pointer->CH2, ADC_CH_INPUTMODE_SINGLEENDED_gc, ADC_CH_GAIN_1X_gc );
ADC_Ch_InputMode_and_Gain_Config( &ADC_Pointer->CH3, ADC_CH_INPUTMODE_SINGLEENDED_gc, ADC_CH_GAIN_1X_gc );
// Route the channels to different pins
// Note that in Single Ended Mode, there is no negative input
ADC_Ch_InputMux_Config( &ADC_Pointer->CH0, ADC_CH_MUXPOS_PIN1_gc, 0 );
ADC_Ch_InputMux_Config( &ADC_Pointer->CH1, ADC_CH_MUXPOS_PIN2_gc, 0 );
ADC_Ch_InputMux_Config( &ADC_Pointer->CH2, ADC_CH_MUXPOS_PIN3_gc, 0 );
ADC_Ch_InputMux_Config( &ADC_Pointer->CH3, ADC_CH_MUXPOS_PIN4_gc, 0 );
// Sample rate is CPUFREQ / 32. @ 2 MHz this equals 62,5ksps
ADC_Prescaler_Config( ADC_Pointer, ADC_PRESCALER_DIV32_gc);
// Set up ADCx to have unsigned conversion mode and 8 bit resolution
ADC_ConvMode_and_Resolution_Config( ADC_Pointer, false, ADC_RESOLUTION_8BIT_gc );
// Set reference voltage on ADCx to be VCC/1.6 V
ADC_Reference_Config( ADC_Pointer, ADC_REFSEL_VCC_gc );
// Enable the ADC
ADC_Enable( ADC_Pointer );
// Wait until common mode voltage is stable. Default clk is 2MHz and
// therefore within the maximum frequency to use this function.
ADC_Wait_8MHz( ADC_Pointer );
}
//-----------------------------------------------------------------------------
// 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);
}
