An analog-to-digital converter is a device which converts continuous signals to discrete digital numbers. Typically, an ADC is an electronic device that converts an input analog voltage or current to a digital number proportional to the magnitude of the voltage or current. The output is taken on the LED s. This is an intermediate circuit, which finds lot of applications. ADC needs an external clock to run. The circuit describes how a D-flip flop can be used to provide the external clock.
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This tutorial will provide you basic information regarding this ADC, testing in free run mode and interfacing example with with sample program in C and assembly. This part of the tutorial was written by Chinmay Das. Normally analogue-to-digital converter ADC needs interfacing through a microprocessor to convert analogue data into digital format.
This requires hardware and necessary software, resulting in increased complexity and hence the total cost. The circuit of A-to-D converter shown here is configured around ADC , avoiding the use of a microprocessor.
It works on the principle of successive approximation. It has a total of eight analogue input channels, out of which any one can be selected using address lines A, B and C. However, the circuit shown here is built to operate in its continuous mode without using any microprocessor. The input control signal SC, being active-low, initiates start of conversion at falling edge of the pulse, whereas the output signal EOC becomes high after completion of digitization.
As the conversion starts, EOC signal goes high. Thus, it provides continuous 8-bit digital output corresponding to instantaneous value of analogue input. The ADC IC requires clock signal of typically kHz, which can be easily derived from an Astable multi-vibrator constructed using inverter gates.
Since ADC works in the continuous mode, it displays digital output as soon as analogue input is applied. The decimal equivalent digital output value D for a given analogue input voltage Vin can be calculated from the relationship.
If you have any queries, doubts or feedback on this tutorial please share in our discussion forum. If you want us to write tutorial for more devices please let us know in the forum. Rickey's World Toggle sidebar.
Table of Content. Note: Reset and oscillator circuit is not shown in above circuit, But its needed for Hidden category: RW Templates.
8051 – ADC0808 Interfacing
ADC is the Analog to Digital converter , which converts analog data into digital format; usually it is used to convert analog voltage into digital format. Analog signal has infinite no of values like a sine wave or our speech, ADC converts them into particular levels or states, which can be measured in numbers as a physical quantity. Instead of continuous conversion, ADC converts data periodically, which is usually known as sampling rate. Telephone modem is one of the examples of ADC, which is used for internet, it converts analog data into digital data, so that computer can understand, because computer can only understand Digital data. The major advantage, of using ADC is that, we noise can be efficiently eliminated from the original signal and digital signal can travel more efficiently than analog one. In present time there are lots of microcontrollers in market which has inbuilt ADC with one or more channels. And by using their ADC register we can interface.
Interfacing ADC to 8051
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Interfacing ADC0808 To 8051
Samsung ICRJ 2. In lot of embedded systems microcontrollers needs to take analog input. For interfacing these sensors to microcontrollers we require to convert the analog output of these sensors to digital so that the controller can read it. ADC is a Successive approximation type with 8 channels i. The device contains 8-channels.
ADC Interfacing with 8051
The data we process in a microcontroller normally deals with digital signals. But there may a situation where we have to deal with external inputs such as analog signals. All most all the input signals from physical sensors are of analog signals. In such cases, we can interface the microcontroller with an external device such as an ADC to convert the analog signal to a digital signal. Because our microcontrollers can only understand 0 and 1.