There are different cheap but powerful Chinese development boards with different STM32H7 chips from DevEBox and WeAct. STM32H750VBT6 – 128K flash STM32H743VIT6 – 2048K flash I recommend to use the STM32H743VIT6 with the 2MB of flash memory. Please note that this is still only half of what you get with an ESP32 but you get an SD drive and 8MB SPI/QSPI Flash! The STM32H7XX processors are based on the 32-bit Arm Cortex®-M7 core, running at Read more…
Currently it is already possible in the Arduino AudioTools Library to define some processing chains: Audio Objects are connected to other objects e.g. by adding the dependent object as parameter in the constructor. Since the very beginning of the library, I planned to have some Pipeline class that would help to define such chains in a more intuitive way. I finally committed this functionality to the Github. Further information can be found in the Wiki
I am providing a Bluetooth A2DP audio library for the ESP32, which can receive audio from a Bluetooth Source (e.g. a mobile phone) and play it via the I2S API provided by the IDF framework. Unfortunately Espressif has decided to go for a completely new I2S API which means that my integration needs to be rewritten. For quite some time now, I am supporting this new API via my AudioTools library, and I was considering Read more…
So far I have always used the Arduino loop to do the audio processing with the hint, that there must not be any longer delay added to the processing. If you have some blocking functions in the loop, the solution is to run the audio in a separate task. I have added some nice concurrency C++ classes to my framework which help that we can keep the sketch quite short. Arduino Example Sketch I am Read more…
I am providing an Arduino MP3 and AAC decoder library for Arduino which is based on libhelix. In this library I added a simple Arduino inspired C++ API. This was one of my first libraries and I found my implementation quite confusing. So it was time to do some refactoring to clean things up. After all, the C API should be quite easy to use and there must be some reason why I ended up Read more…
There are some DACs out there that only support 32 bits: E.g the ES9018K2M module which is sold as high end HIFI DAC. Therefore sometimes it is necessary to change the sample size e.g. from 16 to 32 bits when your codec produces 16 bits. This can be easily done with the help of the NumberFormatConverterStream class of the Arduino Audio Tools library: I2SStream i2s; // final output of decoded stream NumberFormatConverterStream fc(i2s); // write Read more…
Mozzi brings your Arduino to life by allowing it to produce much more complex and interesting growls, sweeps and chorusing atmospherics. These sounds can be quickly and easily constructed from familiar synthesis units like oscillators, delays, filters and envelopes. One of the strong points of my AudioTools library is, that we also support extensive communication scenarios. In this example we show how we can output the sound generated by Mozzi to a Bluetooth Speaker using Read more…
Recently there was a discussion on how to output more then 2 channels via I2S. I2S is limited to 2 channels, but the ESP32 has 2 I2S ports, so we can output a maximum of 4 channels! Arduino Sketch I have added a small example that shows how this can be done using my AudioTools library: #include <SPI.h> #include <SD.h> #include “AudioTools.h” #include “AudioCodecs/CodecMP3Helix.h” const int chipSelect=10; AudioInfo info(44100, 2, 16); I2SStream i2s_1; // final Read more…
Mozzi brings your Arduino to life by allowing it to produce much more complex and interesting growls, sweeps and chorusing atmospherics. These sounds can be quickly and easily constructed from familiar synthesis units like oscillators, delays, filters and envelopes. Mozzi supports quite a lot of different Micro controllers, but it does not have any output method that would let you capture the audio to a stream of data, so I have added some simple integration Read more…
Arrays The best way to allocate an Array of data in the AudioTools is by using a Vector. E.g. Vector<int16_t> vector{100000}; is allocating a vector of 100’000 2 byte signed integers. RAM and PSRAM The ESP32 has a few hundred kilobytes of internal RAM, residing on the same die as the rest of the chip components. It can be insufficient for audio, so it has the ability to use up to 4 MB of external Read more…