ADC
The easiest way to do analog to digital conversion is to use an IC such as the ADC0804 that does the work for us.
Analog to digital conversion is the process by which an analog quantity is converted to digital form. It is necessary when measured quantities must be in digital form for processing in a computer or for display or storage. Several types of ADC’S are available.The most widely used method of A/D conversion is successive approximation. It has much faster conversion time than the other methods. It also has a fixed conversion time that is the same for any value of the analog input.
To be able to implement analog to digital conversion using the ADC0804LCN 8-bit A/D converter. We have designed a circuit and program the chip so that when an analog signal is given as input, the equivalent digital voltage is displayed on an LCD display. Thus, in effect, our circuit should function like a simple voltmeter.
The ability to convert analog signals to digital and vice-versa is very important in signal processing. The objective of an A/D converter is to determine the output digital word corresponding to an analog input signal.
The A/D converter operates on the successive approximation principle. Analog switches are closed sequentially by successive-approximation logic until the analog differential input voltage [Vin(+) - Vin(-)] matches a voltage derived from a tapped resistor string across the reference voltage.
The normal operation proceeds as follows. On the high-to-low transition of the WR input, the internal SAR latches and the shift-register stages are reset, and the INTR output will be set high. As long as the CS input and WR input remain low, the A/D will remain in a reset state. Conversion will start from 1 to 8 clock periods after at least one of these inputs makes a low-to-high transition. After the requisite number of clock pulses to complete the conversion, the INTR pin will make a high-to-low transition. This can be used to interrupt a processor, or otherwise signal the availability of a new conversion. A RD operation (with CS low) will clear the INTR line high again. The device may be operated in the free-running mode by connecting INTR to the WR input with CS=0.
Since this is an 8-bit A/D converter, a voltage from 0-5V. O will be represented as 0000 0000 (0 in decimal) and 5V is represented as 1111 1111 (256 in decimal). To convert a value X volt to decimal, use the following formula:
X * 5.0
-------
256
To get a better resolution, and display the value as a floating-point number, we can multiply the numerator by a factor of 100, 1000 etc. and then print the voltage accordingly.
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The easiest way to do analog to digital conversion is to use an IC such as the ADC0804 that does the work for us.
Analog to digital conversion is the process by which an analog quantity is converted to digital form. It is necessary when measured quantities must be in digital form for processing in a computer or for display or storage. Several types of ADC’S are available.The most widely used method of A/D conversion is successive approximation. It has much faster conversion time than the other methods. It also has a fixed conversion time that is the same for any value of the analog input.
To be able to implement analog to digital conversion using the ADC0804LCN 8-bit A/D converter. We have designed a circuit and program the chip so that when an analog signal is given as input, the equivalent digital voltage is displayed on an LCD display. Thus, in effect, our circuit should function like a simple voltmeter.
The ability to convert analog signals to digital and vice-versa is very important in signal processing. The objective of an A/D converter is to determine the output digital word corresponding to an analog input signal.
The A/D converter operates on the successive approximation principle. Analog switches are closed sequentially by successive-approximation logic until the analog differential input voltage [Vin(+) - Vin(-)] matches a voltage derived from a tapped resistor string across the reference voltage.
The normal operation proceeds as follows. On the high-to-low transition of the WR input, the internal SAR latches and the shift-register stages are reset, and the INTR output will be set high. As long as the CS input and WR input remain low, the A/D will remain in a reset state. Conversion will start from 1 to 8 clock periods after at least one of these inputs makes a low-to-high transition. After the requisite number of clock pulses to complete the conversion, the INTR pin will make a high-to-low transition. This can be used to interrupt a processor, or otherwise signal the availability of a new conversion. A RD operation (with CS low) will clear the INTR line high again. The device may be operated in the free-running mode by connecting INTR to the WR input with CS=0.
Since this is an 8-bit A/D converter, a voltage from 0-5V. O will be represented as 0000 0000 (0 in decimal) and 5V is represented as 1111 1111 (256 in decimal). To convert a value X volt to decimal, use the following formula:
X * 5.0
-------
256
To get a better resolution, and display the value as a floating-point number, we can multiply the numerator by a factor of 100, 1000 etc. and then print the voltage accordingly.
BACK to Content Page
. Next Page
. Previous Page
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