We will also see the sinewave generation using DAC. The Digital to Analog converter DAC is a device, that is widely used for converting digital pulses to analog signals. There are two methods of converting digital signals to analog signals. This method can achieve a much higher degree of precision.
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ADC Free running Circuit 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. ADC Clock input.
Interfacing DAC with 8051 Microcontroller