DSP Signal Generator Implementation On C6713 DSK - ComLab

3 Implementation
In this section implementation of signal generator on C6713 DSK is discussed. For the ease of
reader different functionalities of signal generator are discussed as independent modules where
later all these modules are incorporated in a single program. To access the source code of this
program, please refer to the file “sine_varFreq.c” which is present in the folder “sine_varFreq”,
included in the attached CD-ROM. It is assumed that the reader has a basic knowledge of C/C++
and has read [4].
3.1 Waveform Generation
The C6713 DSK can be used to generate various types of waveforms which have wide range of
applications in communication systems. In this section generation of periodic waveforms namely
sine wave, square wave, triangular wave, sawtooth wave and multi tone signal generation is
discussed.
3.1.1 Sine Wave Generation
One of the main things to take in account in generating any waveform is writing the sample
values of waveform on the codec at every sampling instant. In the DAC done at the codec these
sample values of the waveform are first oversampled (to smoothen the waveform) and are then
fed to a reconstruction filter (to cut frequencies out of band of interest).
There are two techniques for sending the data to codec namely polling technique and interrupt
technique. Polling technique uses a continuous procedure of testing when the data is ready.
Although it is simpler technique than interrupt technique, it is less efficient since the input and
output data needs to be continuously tested to determine when they are ready to be received or
transmitted. Figure 3.1 shows sine wave generated using interrupts technique, source code is
shown in figure 3.2.
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