Implementation of enhancing ADC resolution by oversampling - Revision history

Admin: /* Author */

2013-03-28T11:52:45Z

Author

2013-03-28T10:31:52Z

Test Schematic

2013-03-28T10:31:07Z

Description

2013-03-28T10:30:31Z

Author

2013-03-28T10:30:01Z

Example - 15bit

2013-03-28T10:29:27Z

Example - 14bit

2013-03-28T10:28:44Z

2013-03-28T10:06:35Z

2013-03-28T10:06:20Z

2013-03-28T10:05:53Z

← Older revision		Revision as of 11:52, 28 March 2013
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	'''Email Address:''' Dalvand@ut.ac.ir		'''Email Address:''' Dalvand@ut.ac.ir
		+
		+	[[Category:Projects]]

← Older revision		Revision as of 10:31, 28 March 2013
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−	[[File:Enhadc sch.jpg\|center]]	+	[[File:Enhadc sch.jpg\|center\|700px\|Schematic]]

	== Example - 13bit ==		== Example - 13bit ==

@@ Line 5: / Line 5: @@
 The ADCs reference voltage and the ADCs resolution define the ADC step size. The ADC’s reference voltage, VREF, may be selected to AVCC, an internal 2.56V / 1.1V reference, or a reference voltage at the AREF pin. A lower VREF provides a higher voltage precision but minimizes the dynamic range of the input signal. If the 2.56V VREF is selected, this will give the user ~2.5mV accuracy on the conversion result, and the highest input voltage that is measured is 2.56V. Alternatively one could consider using the ADC input channels with gain stage. This will give the user the possibility of measuring an analog signal with better voltage precision, at the expense of the ADCs dynamic range. If it is not acceptable to trade dynamic range for better voltage resolution, one could choose to trade oversampling of the signal for improved resolution. This method is however limited by the characteristic of the ADC: Using oversampling and decimation will only lower the ADCs quantization error, it does not compensate for the ADCs integral non-linearity.
 <p style="text-align: center;"><br/>'''Table: Resolution option'''</p>
-<br/>[[File:Enhadc table1.jpg|center|Enhadc table1.jpg]]
+<br/>[[File:Enhadc table1.jpg|center|400px|Enhadc table1.jpg]]
 <br/>This method is based on Nyquist theorem that provide in Atmel AVR site

@@ Line 200: / Line 200: @@
 == Author ==
-Written by: Mohammad Jafar Dalvand, University of Tehran, Iran
+'''Written by:''' Mohammad Jafar Dalvand, University of Tehran, Iran
-Email Address: Dalvand@ut.ac.ir
+'''Email Address:''' Dalvand@ut.ac.ir

← Older revision		Revision as of 10:30, 28 March 2013
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	== Example - 15bit ==		== Example - 15bit ==

		+	<source lang="bascomavr">
		+	$regfile = "m16def.dat"
		+	$crystal = 8000000
		+
		+	'$lib "mcsbyte.lbx" ' for smaller code
		+
		+
		+	Config Lcdbus = 4
		+	Config Lcdpin = Pin , Db4 = Portb.3 , Db5 = Portb.2 , Db6 = Portb.1 , Db7 = Portb.0 , E = Portb.4 , Rs = Portb.5
		+	Config Lcd = 16 * 2
		+
		+
		+	Config Adc = Single , Prescaler = Auto , Reference = Avcc
		+	Stop Adc
		+	Dim X As Word , Y As Word , C(2) As Single , N As Word , Sumx As Long , Sumy As Long
		+	Dim Sy As String * 22 , Sx As String * 22 , Vx As String * 22 , Vy As String * 22
		+	Cursor Off
		+	Cls
		+
		+	Start Adc
		+	Do
		+	Sumy = 0
		+	Sumx = 0
		+	For N = 1 To 1024
		+	X = Getadc(0)
		+	'Power Adcnoise
		+	Y = Getadc(1)
		+	'Power Adcnoise
		+	Sumy = Sumy + Y
		+	Sumx = Sumx + X
		+	Next A
		+
		+	'Sy = Bin(sumy)
		+	'Sx = Bin(sumx)
		+	'Vy = Right(sy , 5)
		+	'Vx = Right(sx , 5)
		+	'C(1) = Val(vy)
		+	'C(2) = Val(vx)
		+	C(1) = Sumx / 32.0
		+	C(2) = Sumy / 32.0
		+	C(1) = C(1) - 14339
		+	C(2) = C(2) - 14339
		+	C(1) = C(1) * 0.0440
		+	C(1) = C(1) + 14 'callibration value
		+	C(2) = C(2) * 0.0440
		+	C(2) = C(2) - 14 'callibration value
		+	Locate 1 , 1
		+	Lcd "X=" ; Fusing(c(1) , "#.###")
		+	'Lcd Sy
		+	Locate 2 , 1
		+	Lcd "Y=" ; Fusing(c(2) , "#.###")
		+	'Lcd Sx
		+	Loop
		+
		+	End 'end program
		+	</source>

	== Author ==		== Author ==

← Older revision		Revision as of 10:29, 28 March 2013
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	== Example - 14bit ==		== Example - 14bit ==

		+	<source lang="bascomavr">
		+	$regfile = "m16def.dat"
		+	$crystal = 8000000
		+
		+	'$lib "mcsbyte.lbx" ' for smaller code
		+
		+
		+	Config Lcdbus = 4
		+	Config Lcdpin = Pin , Db4 = Portb.3 , Db5 = Portb.2 , Db6 = Portb.1 , Db7 = Portb.0 , E = Portb.4 , Rs = Portb.5
		+	Config Lcd = 16 * 2
		+
		+
		+	Config Adc = Single , Prescaler = Auto , Reference = Avcc
		+	Stop Adc
		+	Dim X As Word , Y As Word , C(2) As Single , N As Word , Sumx As Long , Sumy As Long
		+	Dim Sy As String * 18 , Sx As String * 18 , Vx As String * 14 , Vy As String * 14
		+	Cursor Off
		+	Cls
		+
		+	Start Adc
		+	Do
		+	Sumy = 0
		+	Sumx = 0
		+	For N = 1 To 256
		+	X = Getadc(0)
		+	'Power Adcnoise
		+	Y = Getadc(1)
		+	'Power Adcnoise
		+	Sumy = Sumy + Y
		+	Sumx = Sumx + X
		+	Next A
		+
		+	'Sy = Bin(sumy)
		+	'Sx = Bin(sumx)
		+	'Vy = Right(sy , 4)
		+	'Vx = Right(sx , 4)
		+	'C(1) = Val(vy)
		+	'C(2) = Val(vx)
		+	C(1) = Sumx / 16.0
		+	C(2) = Sumy / 16.0
		+	C(1) = C(1) - 7169
		+	C(2) = C(2) - 7169
		+	C(1) = C(1) * 0.0880
		+	'C(1) = C(1) + 14 'callibration value
		+	C(2) = C(2) * 0.0880
		+	'C(2) = C(2) - 14 'callibration value
		+	Locate 1 , 1
		+	Lcd "X=" ; Fusing(c(1) , "#.##")
		+	'Lcd Sy
		+	Locate 2 , 1
		+	Lcd "Y=" ; Fusing(c(2) , "#.##")
		+	'Lcd Sx
		+	Loop
		+
		+	End 'end program
		+	</source>

	== Example - 15bit ==		== Example - 15bit ==

← Older revision		Revision as of 10:28, 28 March 2013
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	== Example - 13bit ==		== Example - 13bit ==

		+
		+	<source lang="bascomavr">
		+	$regfile = "m16def.dat"
		+	$crystal = 8000000
		+
		+	'$lib "mcsbyte.lbx" ' for smaller code
		+
		+
		+	Config Lcdbus = 4
		+	Config Lcdpin = Pin , Db4 = Portb.3 , Db5 = Portb.2 , Db6 = Portb.1 , Db7 = Portb.0 , E = Portb.4 , Rs = Portb.5
		+	Config Lcd = 16 * 2
		+
		+
		+	Config Adc = Single , Prescaler = Auto , Reference = Avcc
		+	Stop Adc
		+	Dim X As Word , Y As Word , C(2) As Single , N As Word , Sumx As Long , Sumy As Long
		+	Dim Sy As String * 18 , Sx As String * 18 , Vx As String * 14 , Vy As String * 14
		+	Cursor Off
		+	Cls
		+
		+	Start Adc
		+	Do
		+	Sumy = 0
		+	Sumx = 0
		+	For N = 1 To 64
		+	Y = Getadc(0)
		+	'Power Adcnoise
		+	X = Getadc(1)
		+	'Power Adcnoise
		+	Sumy = Sumy + Y
		+	Sumx = Sumx + X
		+	Next A
		+
		+	'Sy = Bin(sumy)
		+	'Sx = Bin(sumx)
		+	'Vy = Right(sy , 3)
		+	'Vx = Right(sx , 3)
		+	'C(1) = Val(vy)
		+	'C(2) = Val(vx)
		+	C(1) = Sumy / 8
		+	C(2) = Sumx / 8
		+	C(1) = C(1) - 3584
		+	C(2) = C(2) - 3584
		+	C(1) = C(1) * 0.175
		+	C(2) = C(2) * 0.175
		+
		+	Locate 1 , 1
		+	Lcd "X=" ; Fusing(c(2) , "#.##")
		+	'Lcd Sy
		+	Locate 2 , 1
		+	Lcd "Y=" ; Fusing(c(1) , "#.##")
		+	'Lcd Sx
		+	Loop
		+
		+	End 'end program
		+	</source>

	== Example - 14bit ==		== Example - 14bit ==

@@ Line 12: / Line 12: @@
 One of the most popular applications of the ADXL202E is tilt measurement. An accelerometer uses the force of gravity as an input vector to determine orientation of an object in space. An accelerometer is most sensitive to tilt when its sensitive axis is perpendicular to the force of gravity, i.e., parallel to the earth’s surface. At this orientation its sensitivity to changes in tilt is highest. When the accelerometer is oriented on axis to gravity, i.e., near its +1 g or –1 g reading, the change in output acceleration per degree of tilt is negligible. When the accelerometer is perpendicular to gravity, its output will change nearly 17.5 mg per degree of tilt, but at 45° degrees it is changing only at 12.2 mg per Degree and resolution declines. The following table illustrates the changes in the X and Y axes as the device is tilted ± 90° through gravity.
+<p style="text-align: center;"><br/>'''Table: How the X and Y axes respond to changes in tilt'''</p>
-<br/>Table: How the X and Y axes respond to changes in tilt
+<br/>[[File:Enhadc table2.jpg|center|Enhadc table2.jpg]]
-−
 <br/>[[File:Enhadc table2.jpg|center]]
 == Test Schematic ==