Tag Archives: audio processing


Digital voice recorder design using C8051F411

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Designing a digital voice recorder requires sampling the audio channel, compress and decompress the signal, and store and retrieve the samples. Silicon Labs provides a reference for designing a digital voice recorder using their C8051F411 microcontroller, which has a 12-bit ADC, and a 12-bit DAC, available on chip. The ‘F411 samples the voice signal using the ADC, compresses the sample using DPCM (Differential Pulse Code Modulation), and sends the sample to the external Flash using the SPI. Later, the microcontroller retrieves the samples from the external Flash, decompresses them, and sends them to the speaker through the DAC. This reference design can record up to 87 seconds of audio.

Voice recorder design reference

Voice recorder design reference

Tutorial on Advanced Arduino Sound Synthesis

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The easiest way of producing a sound using an Arduino board is by bit-banging its I/O pin driving a buzzer or speaker. However, if you want to go beyond simple beeps and synthesis complex and more interesting sounds, you need a better understanding of the Arduino hardware as well as the theory behind wave synthesis. Here’s a wonderful tutorial from Makezine that describes the fundamental concept of synthesizing waveform and how to manipulate it in real time.

Arduino sound synthesis

Arduino sound synthesis

Build an electric guitar tuner using Arduino

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Check this latest instructable on making an Arduino guitar tuner. The audio signal from an electric guitar is amplified and fed to an ADC channel of Arduino, which further processes the signal to extract the major frequency component in the audio. Based on the detected frequency, an LED lights up to show the note of the audio. Besides, it also indicates whether the string being played is sharp, flat, or in tune.

Arduino guitar tuner