/* 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;
}
void adc_temp_init(void)
{
// enable 1V reference and temperature modules
ADC_BandgapReference_Enable(&ADCB);
ADC_TempReference_Enable(&ADCB);
// load calibration from signature bytes
ADC_CalibrationValues_Load(&ADCB);
// Conversion mode and resolution (12 bit right-aligned)
ADC_ConvMode_and_Resolution_Config(&ADCB,
ADC_ConvMode_Unsigned, ADC_RESOLUTION_12BIT_gc);
// prescaler from system clock (fastest)
ADC_Prescaler_Config(&ADCB, ADC_PRESCALER_DIV4_gc);
// internal 1V reference
ADC_Reference_Config(&ADCB, ADC_REFSEL_INT1V_gc);
// channel 0 for temperature
ADC_Ch_InputMode_and_Gain_Config(&ADCB.CH0,
ADC_CH_INPUTMODE_INTERNAL_gc,
ADC_CH_GAIN_1X_gc);
ADC_Ch_InputMux_Config(&ADCB.CH0, ADC_CH_MUXINT_TEMP_gc, ADC_CH_MUXNEG_PIN0_gc);
// channel 1 for VCC/10
ADC_Ch_InputMode_and_Gain_Config(&ADCB.CH1,
ADC_CH_INPUTMODE_INTERNAL_gc,
ADC_CH_GAIN_1X_gc);
ADC_Ch_InputMux_Config(&ADCB.CH1, ADC_CH_MUXINT_SCALEDVCC_gc, ADC_CH_MUXNEG_PIN0_gc);
ADC_Enable(&ADCB);
ADC_Wait_8MHz(&ADCB);
}
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 );
}
int main(void){
char xbeebuffer[100];
int adcSample;
/**Setup Xbee*/
PORTD.DIR = 0b00001000;
PORTF.DIR = 3;
/**Setup interrupts*/
PMIC.CTRL |= PMIC_LOLVLEX_bm | PMIC_MEDLVLEX_bm | PMIC_HILVLEX_bm |
PMIC_LOLVLEN_bm | PMIC_MEDLVLEN_bm | PMIC_HILVLEN_bm;
sei();
USART_InterruptDriver_Initialize(&xbee, &USARTD0, USART_DREINTLVL_LO_gc);
USART_Format_Set(xbee.usart, USART_CHSIZE_8BIT_gc, USART_PMODE_DISABLED_gc, false);
USART_RxdInterruptLevel_Set(xbee.usart, USART_RXCINTLVL_HI_gc);
USART_Baudrate_Set(&USARTD0, 12 , 0);
USART_Rx_Enable(xbee.usart);
USART_Tx_Enable(xbee.usart);
ADC_Ch_InputMode_and_Gain_Config(&ADC_BK.CH0, ADC_CH_INPUTMODE_DIFF_gc, ADC_DRIVER_CH_GAIN_NONE); // differential mode, no gain
ADC_Ch_InputMux_Config(&ADC_BK.CH0, pin, ADC_CH_MUXNEG_PIN1_gc);
ADC_Reference_Config(&ADC_BK, ADC_REFSEL_VCC_gc); // use Vcc/1.6 as ADC reference
ADC_ConvMode_and_Resolution_Config(&ADC_BK, ADC_ConvMode_Signed, ADC_RESOLUTION_12BIT_gc);
ADC_Prescaler_Config(&ADC_BK, ADC_PRESCALER_DIV32_gc);
while(1){
if(readdata){
readdata = 0;
if(input == 'r'){
adc_start_conversion(&ADCA, ADC_CH0);
adc_wait_for_interrupt_flag(&ADCA, ADC_CH0);
adcSample = adcch_get_signed_result(&ADCA, 0);
sprintf(xbeebuffer, " %d\n\r", adcSample);
sendstring(&xbee, xbeebuffer);
}
}
}
}
void adc_init(void)
{
ADC_CalibrationValues_Load(&ADCA);
ADC_ConvMode_and_Resolution_Config(&ADCA,
ADC_ConvMode_Unsigned, ADC_RESOLUTION_12BIT_gc);
ADC_Prescaler_Config(&ADCA, ADC_PRESCALER_DIV16_gc);
ADC_Reference_Config(&ADCA, ADC_REFSEL_VCC_gc);
ADC_Ch_InputMode_and_Gain_Config(&ADCA.CH0,
ADC_CH_INPUTMODE_SINGLEENDED_gc,
ADC_CH_GAIN_1X_gc);
ADC_Ch_InputMux_Config(&ADCA.CH0, ADC_CH_MUXPOS_PIN7_gc, ADC_CH_MUXNEG_PIN0_gc);
ADC_Enable(&ADCA);
ADC_Wait_8MHz(&ADCA);
}
int main(void)
{
// Add code to sweep CH0 and CH1 in free running mode
// Use the function call in the adc_driver.h
ADC_SweepChannels_Config( &ADCB, ADC_SWEEP_01_gc);
//Enable internal temperature sensor, to be used by CH1
ADC_TempReference_Enable(&ADCB);
// Setup CH1 to have single ended input as in task1 and task2
ADC_Ch_InputMode_and_Gain_Config(&ADCB.CH0,
ADC_CH_INPUTMODE_SINGLEENDED_gc,
ADC_CH_GAIN_1X_gc);
// Set input to CH0 in ADC B to be PIN 1
ADC_Ch_InputMux_Config(&ADCB.CH0,
ADC_CH_MUXPOS_PIN1_gc,
0);
// Setup CH1 to read internal signal
ADC_Ch_InputMode_and_Gain_Config(&ADCB.CH1,
ADC_CH_INPUTMODE_INTERNAL_gc,
ADC_CH_GAIN_1X_gc);
// CH1 is set up to measure the internal temperature sensor
ADC_Ch_InputMux_Config(&ADCB.CH1,
ADC_CH_MUXINT_TEMP_gc,
0);
// Set up ADC B to have unsigned conversion mode and 12 bit resolution
ADC_ConvMode_and_Resolution_Config(&ADCB, false, ADC_RESOLUTION_12BIT_gc);
// Set reference voltage on ADC B to be VCC/1.6 V
ADC_Reference_Config(&ADCB, ADC_REFSEL_VCC_gc);
// Sample rate is CPUFREQ/16.
ADC_Prescaler_Config(&ADCB, ADC_PRESCALER_DIV16_gc);
// Enable ADC B
ADC_Enable(&ADCB);
// Wait until common mode voltage is stable. Default clk is 2MHz and
// therefore within the maximum frequency to use this function.
ADC_Wait_8MHz(&ADCB);
// Enable ADC B free running mode
ADC_FreeRunning_Enable(&ADCB);
// Set the LEDPORT as output
LEDPORT.DIR = 0xFF;
while(1) {
// When CH1IF is set, both conversions are done since CH0 is started first
// Wait for CH1IF to be set
do {
} while ((ADCB.INTFLAGS & ADC_CH1IF_bm) != ADC_CH1IF_bm);
// Clear CH1 Interrupt Flag
ADCB.INTFLAGS |= ADC_CH1IF_bm;
// Read the CH0 result register, 12 bit unsigned (0-4095)
ADC_result_CH0 = ADCB.CH0RES;
// Read the CH1 result register
ADC_result_CH1 = ADCB.CH1RES;
// Shift CH0 result to get the 4 MSB of the input signal on the 4 LSB of the LEDs
ADC_result_CH0 >>= 8;
// Shift CH1 result to get the 4 MSB of the temperature on the 4 MSB of the LEDs
// Also downscale it to 4 bit. Try touching the Xmega to warm it up.
ADC_result_CH1 = ((ADC_result_CH1 - 1) / 16);
ADC_result_CH1 <<= 4;
// Output on the LEDs, the 4 MSB is the internal temperature reading,
// and the 4 LSB is the single ended input reading,
LEDPORT.OUT = ~( (ADC_result_CH1 & 0x00F0) | (ADC_result_CH0 & 0x000F));
}
}
//-----------------------------------------------------------------------------
// 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);
}
