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Category Archives for Firmware / embedded
An earlier play-v6 version
I started working on play-v6 in the first days of December 2013 and in about three weeks I could play “Jingle Bells”: in time for Christmas :-) That early version (450 git commits ago) had lots of limitations but reproduced … Continue reading
New toy
It is programmable but it does not (usually) run a program: it is an FPGA evaluation and learning board. For lazy designers like myself, it beats building circuit prototypes the way I used to… ‘some’ time ago: This video card … Continue reading
Bit depth, PWM and frequency
I have briefly shown how to resample a digital audio recording to play it out at a different pitch (i.e. at a different frequency). Using PWM (pulse-width modulation) as a form of DAC (digital to analog converter) introduces some additional … Continue reading
Resampling digitized audio
We have seen how to reduce the size of the digitized guitar string sound, to make it fit into the microcontroller Flash memory. Reproducing the original sound at the same frequency is easy: it just requires feeding the digitized values … Continue reading
Squeezing audio samples into Arduino memory
I digitized 6 seconds of a guitar string sound, on a single channel (i.e. monophonic) using a 44.1 kHz sampling rate, so the digitized sound contained: 44100 samples/s * 6 s = 264600 samples Each sample from my PC audio … Continue reading
How a PWM DAC works
We have seen that a sound is digitized using a microphone to transform it into an electric signal, then by reading the istantaneous voltage of that signal at regular intervals with an Analog to Digital Converter (ADC), getting a series … Continue reading
Digitizing a guitar string
When I bought an 8-bit Arduino Uno, my first idea was to make a guitar simulator, just for fun (and, to be honest, also to see if I still remembered those skills after so many years). A guitar has six … Continue reading
8-bit Arduino music synthesis
This series of posts will be both an introduction to (a type of) digital music and a description of the techniques and tricks I used in my play-v6 software music synthesizer. It will not be a planned route, but rather … Continue reading
Don’t stop at the Arduino libraries
A manager at an electronics company once told me: “Many job seekers come here thinking they are embedded programmers, just because they can program an Arduino“. What did he mean? Was he referring to the limited capabilities of the 8-bit … Continue reading
play-v6: ‘real’ music from Arduino Uno
With a little bit of C optimization: http://www.erix.it/play-v6