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Audio spectrum analyzer without DSP processor

When dealing with signals, probably the best way is to leave the task for DSP processor as they are optimised to do DSP calculations like FFT, filtering and other digital signal manipulation. But not always a DSP processor is an only solution, especially if you want a low cost and non-critical performance application like an audio spectrum analyser. In this project, an ARM7 (LPC2138) microcontroller is used to do an FFT algorithm. The tricky part about FFT on such microcontrollers is dealing with complex numbers that are also real. The project description shows the whole process of how these problems are solved. Project is set up on ZL6ARM prototype board, which is equipped with all necessary peripherals like LCD, MAX232 converter. The program is developed for ARM-GCC compiler. An audio signal is sampled by LPC2138 internal ADC with the selected sampling frequency of 40 kHz. An FFT algorithm calculates the chunks of 256 samples and produces the spectrum graphs on the PC screen. This is a great project and nice tutorial to get into DSP world. [source] Continue reading