conf_oversampling.h File Reference

Configuration file for XMEGA ADC Oversampling Demo Application.

Copyright (c) 2014-2018 Microchip Technology Inc. and its subsidiaries.

Macros
Oversampling configuration
#define	ADC_OVER_SAMPLED_NUMBER   256
	For each additional bit of ADC resolution, n, the signal must be oversampled 4^n times.To achieve 16 signed bit result from 12 bit signed ADC,we are choosing 4 bit additional resolution. More...
#define	ADC_OVER_SAMP_SCALING_FACTOR   4
	The scale factor, sf, given by sf = 2^n, is the factor, which is the sum of 4^n samples should be divided by, to scale the result properly.n is the desired number of extra bit. More...
#define	ADC_OVER_SAMP_MAX_COUNT   32767
	Define the Maximum ADC count with selected ADC resolution. More...
#define	ADC_NO_OVER_SAMP_MAX_COUNT   2047
	Define the maximum ADC count with selected ADC resolution when no oversampling is done. More...
ADC configuration for oversampling
#define	ADC_OVER_SAMP_POSTIVE_PIN   ADCCH_POS_PIN1
	for oversampling, setting up the positive pin. More...
#define	ADC_OVER_SAMP_NEGATIVE_PIN   ADCCH_NEG_PIN2
	for oversampling, setting up the negative pin. More...
#define	ADC_OVER_SAMP_REFSEL   ADC_REFSEL_AREFB_gc
	Select ADCB reference voltage .Here, selected as, external reference voltage at PortB(at PB0 Pin) More...
#define	ADC_OVER_SAMP_REF_VOLT_IN_MICRO   2500000
	Define the value of actual reference voltage.It is used in analog input value.Here, If external 2.5V is selected as ADC Reference, value of this macro should be reference voltage in microvolt. More...
#define	ADC_GAIN_ERROR_FACTOR   (0xFF97)
	Gain error of ADC which has to be calculated statically for each device. More...

#define ADC_GAIN_ERROR_FACTOR   (0xFF97)

Gain error of ADC which has to be calculated statically for each device.

Gain Error is is deviation of the last output steps midpoint from the ideal line.To measure the gain error: -Increase input voltage from 0 until the last output step -The scaling factor for gain compensation equals the ideal output value for the midpoint of the last step divided by the actual value of the step Here ,given value is for a one specific device, it will vary from device to device and has to be calculated statically. It is calculated as

• (Gain error * 2^16), Here it is, (0.9984 * 2^16)

Referenced by adc_oversampled().

#define ADC_NO_OVER_SAMP_MAX_COUNT   2047

Define the maximum ADC count with selected ADC resolution when no oversampling is done.

Here we configured to get 12 bit signed . result.That is 11 bit Result. Hence the value of this macro will be (2^11)-1, which is 2047

Referenced by adc_oversampled().

#define ADC_OVER_SAMP_MAX_COUNT   32767

Define the Maximum ADC count with selected ADC resolution.

Here we are oversampling to get 16 bit signed result.That is 15 bit Result. Hence the value of this macro will be (2^15)-1, which is 32767

Referenced by adc_oversampled().

#define ADC_OVER_SAMP_NEGATIVE_PIN   ADCCH_NEG_PIN2

for oversampling, setting up the negative pin.

Here, selected PIN2 (PB2 for ADCB) as negative input

Referenced by init_adc().

#define ADC_OVER_SAMP_POSTIVE_PIN   ADCCH_POS_PIN1

for oversampling, setting up the positive pin.

Here, selected PIN1 (PB1 for ADCB) as positive input

Referenced by init_adc().

#define ADC_OVER_SAMP_REF_VOLT_IN_MICRO   2500000

Define the value of actual reference voltage.It is used in analog input value.Here, If external 2.5V is selected as ADC Reference, value of this macro should be reference voltage in microvolt.

Referenced by adc_oversampled().

#define ADC_OVER_SAMP_REFSEL   ADC_REFSEL_AREFB_gc

Select ADCB reference voltage .Here, selected as, external reference voltage at PortB(at PB0 Pin)

#define ADC_OVER_SAMP_SCALING_FACTOR   4

The scale factor, sf, given by sf = 2^n, is the factor, which is the sum of 4^n samples should be divided by, to scale the result properly.n is the desired number of extra bit.

In this example we did choose 4 extra bit. Hence the value is 16, i.e. 2^4.Instead of dividing by 16,we can right shift by 4. Hence this Macro is defined as 4.

Referenced by adc_oversampled().

#define ADC_OVER_SAMPLED_NUMBER   256

For each additional bit of ADC resolution, n, the signal must be oversampled 4^n times.To achieve 16 signed bit result from 12 bit signed ADC,we are choosing 4 bit additional resolution.

Hence signal has to be sampled 4^4( 4 to the power 4 ), i.e. 256 times more samples. Define this Macro as per number of additional samples required,here it did choose as 256 in this example

Referenced by adc_handler(), and init_adc().