vb.net barcode reader USING ANALOG-TO-DIGITAL CONVERSION in Software

Generation Data Matrix ECC200 in Software USING ANALOG-TO-DIGITAL CONVERSION

USING ANALOG-TO-DIGITAL CONVERSION
DataMatrix Reader In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
ECC200 Creator In None
Using Barcode maker for Software Control to generate, create Data Matrix 2d barcode image in Software applications.
2 R1 Input 3 + IC1 741
Data Matrix ECC200 Recognizer In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
Paint Data Matrix ECC200 In Visual C#.NET
Using Barcode creator for .NET Control to generate, create ECC200 image in .NET applications.
7 6 4 Output
Printing Data Matrix 2d Barcode In VS .NET
Using Barcode printer for ASP.NET Control to generate, create DataMatrix image in ASP.NET applications.
Printing Data Matrix ECC200 In .NET Framework
Using Barcode creator for .NET Control to generate, create Data Matrix 2d barcode image in Visual Studio .NET applications.
FIGURE 29.17 Op-amp buffer.
Data Matrix Maker In Visual Basic .NET
Using Barcode creation for .NET framework Control to generate, create DataMatrix image in VS .NET applications.
Encoding Data Matrix 2d Barcode In None
Using Barcode encoder for Software Control to generate, create DataMatrix image in Software applications.
Light-dependent resistor (CdS cell) Output
EAN / UCC - 13 Printer In None
Using Barcode generator for Software Control to generate, create EAN-13 Supplement 5 image in Software applications.
Encoding Code-39 In None
Using Barcode creator for Software Control to generate, create Code 39 image in Software applications.
FIGURE 29.18 Voltage divider.
Code 128 Code Set C Maker In None
Using Barcode drawer for Software Control to generate, create ANSI/AIM Code 128 image in Software applications.
Drawing Bar Code In None
Using Barcode drawer for Software Control to generate, create bar code image in Software applications.
Potentiometer
Drawing Identcode In None
Using Barcode generator for Software Control to generate, create Identcode image in Software applications.
Drawing EAN13 In VB.NET
Using Barcode generation for Visual Studio .NET Control to generate, create EAN-13 Supplement 5 image in VS .NET applications.
Output
Decoding Bar Code In VS .NET
Using Barcode Control SDK for ASP.NET Control to generate, create, read, scan barcode image in ASP.NET applications.
Decode Data Matrix 2d Barcode In Visual Basic .NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in VS .NET applications.
FIGURE 29.19 Potentiometer. I Like a phototransistor, the output of a photodiode is a varying current. This output can
Decoding UCC-128 In VB.NET
Using Barcode recognizer for VS .NET Control to read, scan read, scan image in .NET framework applications.
Encode Barcode In C#
Using Barcode creation for VS .NET Control to generate, create barcode image in Visual Studio .NET applications.
also be converted into a voltage by using a resistor (see Fig. 29.18). (The higher the resistance, the higher the sensitivity of the device.) This output tends to be fairly weak on the order of millivolts instead of volts. Therefore, amplification is usually required.
Barcode Maker In Java
Using Barcode generator for BIRT Control to generate, create bar code image in Eclipse BIRT applications.
UPC A Creation In Java
Using Barcode creator for Java Control to generate, create UCC - 12 image in Java applications.
Using Analog-to-Digital Conversion
Computers are binary devices: their digital data is composed of strings of 0s and 1s, strung together to construct meaningful information. But the real world is analog, where data can be most any value, with literally millions of values between none and lots ! Analog-to-digital conversion is a system that takes analog information and translates it into a digital, or more precisely binary, format suitable for your robot. Many of the sensors
448 INTERFACING WITH COMPUTERS AND MICROCONTROLLERS
you will connect to the robot are analog in nature. These include temperature sensors, microphones and other audio transducers, variable output tactile feedback (touch) sensors, position potentiometers (the angle of an elbow joint, for example), light detectors, and more. With analog-to-digital conversion you can connect any of them to your robot.
HOW ANALOG-TO-DIGITAL CONVERSION WORKS
Analog-to-digital conversion (ADC) works by converting analog values into their binary equivalents. In most cases, low analog values (like a weak light striking a photodetector) might have a low binary equivalent, such as 1 or 2. But a high analog value might have a high binary equivalent, such as 255 or even higher. The ADC circuit will convert small changes in analog values into slightly different binary numbers. The smaller the change in the analog signal required to produce a different binary number, the higher the resolution of the ADC circuit. The resolution of the conversion depends on both the voltage span (0 5 volts is most common) and the number of bits used for the binary value. Suppose the signal spans 10 volts and 8 bits (or a byte) are used to represent various levels of that voltage. There are 256 possible combinations of 8 bits, which means the span of 10 volts will be represented by 256 different values. Given 10 volts and 8 bits of conversion, the ADC system will have a resolution of 0.039 volts (39 millivolts) per step. Obviously, the resolution of the conversion will be finer the smaller the span or the higher the number of bits. With a 10-bit conversion, for instance, there are 1024 possible combination of bits, or roughly 0.009 volts (9 millivolts) per step.
INSIDE THE SUCCESSIVE APPROXIMATION ADC
There are a number of ways to construct an analog-to-digital converter, including successive approximation, single slope, delta-sigma, and flash. Perhaps the most commonly used is the successive approximation approach, which is a form of systematized 20 questions. The ADC arrives at the digital equivalent of any input voltage within the expected range by successively dividing the voltage ranges by two, narrowing the possible result each time. Comparator circuits within the ADC determine if the input value is higher or lower than a built-in reference value. If higher, the ADC branches toward one set of binary values; if lower, the ADC branches to another set. While this sounds like a roundabout way, the entire process takes just a few microseconds. One disadvantage of successive approximation (and some other ADC schemes) is that the result may be inaccurate if the input value changes before the conversion is complete. For this reason, most modern analog-to-digital converters employ a built-in sample and hold circuit (usually a precision capacitor and resistor) that temporarily stores the value until conversion is complete.
ANALOG-TO-DIGITAL CONVERSION ICS
You can construct analog-to-digital converter circuits using discrete logic chips basically a string of comparators strung together. But an easier approach is a special-purpose ADC integrated circuit. These chips come in a variety of forms besides conversion method (e.g., successive approximation, discussed in the last section):
Copyright © OnBarcode.com . All rights reserved.