Tag Archives: PIC18F4550


PIC microcontroller based audio spectrum analyzer

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This project introduces a real-time audio spectrum analyzer based on a PIC18F4550 microcontroller. The spectrum frequency analysis is done with a 16-bit Fast Fourier Transformation (FFT) routine coded in C. It uses a 128×64 GLCD to display the FFT waveform of a live audio signal.

“In order to perform a FFT calculation on an audio signal it is necessary to prepare the audio so the PIC18F4550 can sample the signal. The PIC18F4550 provides several analogue to digital converters (ADCs) which can be used to measure a voltage from 0V to 5V with 10-bit accuracy (0-1023). A typical audio line-out signal is an analogue wave with a peak-to-peak intensity of 1V centred around 0V (i.e. it is an AC signal) as shown by the following oscilloscope trace (from pin W2 of the demo board): Read more

USB Development Board for PIC18F4550

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This article shows how to make a low cost USB development board for PIC18F4550 similar to Microchip’s PICDEM USB FS board. The Microchip’s USB stack examples can be compiled and loaded directly without altering the code. Access to each of the 40 pins is provided through female headers so that the connections could be extended to a breadboard easily during prototyping.

The board has got a LM7805 voltage regulator with a polarity protection. This board will be very helpful in prototyping PIC based USB projects.

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