Hi am Ravi. I would like to know about sine wave generation using 8051 microcontroller and 0808 DAC. My friend Tejas said that the program am looking for will be available here.I want the assembly program made with the help of keil. at present am living at Vadodara. and am pursuing my BE in Elecgrical engineering. now am doing my project on microcontroller so i need help. please help me.
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This section will show how to interface a DAC (digital-to-analog converter) to the 8051. Then we demonstrate how to generate a sine wave on the scope using the DAC.
The digital-to-analog converter (DAC) is a device widely used to convert digital pulses to analog signals. In this section we discuss the basics of interfacing a DAC to the 8051.
Recall from your digital electronics book the two methods of creating a DAC: binary weighted and R/2R ladder. The vast majority of integrated circuit DACs, including the MC1408 (DAC0808) used in this section, use the R/2R method since it can achieve a much higher degree of precision. The first criterion for judging a DAC is its resolution, which is a function of the number of binary inputs. The common ones are 8, 10, and 12 bits. The number of data bit inputs decides the resolution of the DAC since the number of analog output levels is equal to 2″, where n is the number of data bit inputs. Therefore, an 8-input DAC
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Sine wave can be generated using a Microcontroller by sending amplitude values of sine wave from microcontroller to a Digital to Analog Converter(DAC), then passing the output of DAC through a op-amp to get voltage signal and finally filtering the op-amp output voltage to get smooth sine wave. This method can be used with any microcontroller such as 8051, PIC, AVR etc.
The microcontroller stores the amplitude values corresponding to the sine wave. This discrete amplitude value are sent in parallel to a DAC. If for example 8 bit microcontroller is used then the amplitude are represented in 8 bits which are sent in parallel to a 8 bit DAC. The DAC converts the amplitude to analog signal. This is then passed into the Op-Amp. The function of the Op-Amp is to convert the current input from DAC to corresponding voltage output. That is Op-Amp is used as current to voltage converter. The output from the Op-Amp is sine wave with discrete increase in the curve. This is because the sine wave from op-amp contains required sine wave of desired frequency plus other harmonic frequencies. The LPF is therefore used at the end to filter out the harmonic frequencies.
Simulation Illustration
We will illustrate this using Proteus simulation. We will use 8051 microcontroller here but any microcontroller such as PIC, AVR etc can be used. For the DAC we will use the DAC0808. For Op-Amp the LF351 is used. The LPF is a simple RC LPF.
reference;
http://appliedelectronicsengineering.blo...-from.html