#SYNCHRONIZED TONEGENERATOR HOW TO#
#SYNCHRONIZED TONEGENERATOR SOFTWARE#
#SYNCHRONIZED TONEGENERATOR CODE#

So far the only event defined is playback presentation complete but more events and synchronized Unhide MediaSyncEvent class and AudioRecord.startRecording() method with synchronizationĮvent allowing to start audio capture upon occurence of a specific event. Unhide API for synchronous audio capture. More details on how compile this project is here.A46f7680f159571a3ca9fa5928cae2fa6309ee3a

#SYNCHRONIZED TONEGENERATOR CODE#

This code is written in C and can be compiled using the avr-gcc.

LED1, LED2, LED3 – red, green and blue (or other colours of your preference) LEDs.

R1, R2, R3 – resistor 560Ω, see LED Resistor Calculator.

In result program size is ~464 bytes (45.3%). Solution was, combaine some features of naive version – it is DFT with precalculated twiddle factors using in FFT algorithms and do calculation for only real part of complex numbers what is good enough, as for this project. However, it require ~20% more program space and >50% more RAM. It’s worth to note, that originally, algorithm was designed to do calculation for both parts of complex numbers and calculate a signal power as a product for next phase. Popular implementations of FFT (Fast Fourier Transformation) require more program space then offers ATtiny13. FFT algorithms require more space than offers ATtiny13 Accessing data from RAM is a bit faster as it takes extra steps to get data from PROGMEM. In result 31 bytes (48.4%) of RAM has been reserved for arrays and 33 bytes (51.6%) was left to use by program.įor some smartasses that are interested in why twiddle factors are stored not in PROGMEM but in RAM. Solution was, adding precalculated twiddle factors for 6-point DFT, using array of short integers and focusing on calculations only for real part of complex numbers (sic!). FFT algorithms require a lot of RAM, more than offers ATtiny13Įliminations of real numbers was a good optimization trick but still, It was not possible to implement efficient algorithm. Solution was to make it possible to replace all real numbers by integers. It was a critical issue for the project realization. DSP calculations require real numbers what consumes a lot of ATtiny13 resourcesĬalculations on float/double take much of RAM, CPU time and FLASH space.

#SYNCHRONIZED TONEGENERATOR SOFTWARE#

MCU checks all frequency amplitudes, and by toggling LEDs It simulates Software PWM, what in result gives quite good control of LED brightness. Each LED represents a frequency bandwidth. LEDs Visualization (PWM)Īt last, MCU put some visualisation based on information from previous phase. Please note, that to simplify algorithm complexity, only a real part of complex numbers has been used. Because of the Nyquist frequency rule, which is a property of a discrete-time system, we can use only N/2 of samples for further signal analysis. The product of that phase is N values that represents amplitudes of N frequencies, where particular frequency is, F(n) = FS/N. Next, signals are converted from time domain form to the frequency domain using a DFT algorithm. This phase produces N signal samples – discrete signal in the time domain. MCU uses ADC to read analog signal (signal acquisition) with required FS ( Sampling Frequency). The input signal source can be any audio signal. Audio Signal Acquisition (ADC, Signal Sampling) Simplified block diagram is presented bellow. In this project ATtiny13 has a three major tasks: read audio signal, process signal and visualize frequency bands using LEDs.

Project doesn’t require any specific equipment and the parts costs are below 3$. This project also proves that real-time DFT ( Discrete Fourier Transformation) is possible on such small MCU like ATtiny13, which offers only 64B of RAM and 1024B of FLASH. Project uses single ADC ( Analog to Digital Converter) channel for signal acquisition and some DSP ( Digital Signal Processing) calculations that in real-time separate three frequency bands and make the LEDs dance in sync with the music.

#SYNCHRONIZED TONEGENERATOR HOW TO#

This experimental project shows how to use ATtiny13 to synchronize live music and lights with only a few additional components required.

Synchronized tonegenerator