ocrdu / arduino_samd21_audio_player

Simple audio player library for SAMD21G-based Arduinos. Sends an array of samples to the DAC on A0, with optional extrapolation aka oversampling. Intended for playing short sound bites without the need for an external audio player.

A simple (but oversampling) audio player for SAMD21G-based Arduinos

Basically, this library lets you send an array of 8-bit samples to the DAC on pin A0, with optional extrapolation aka oversampling.

I have connected the output pin through a 2.2μF capacitor and a 1kΩ resistor in series to a small and cheap active speaker set like you would use for a computer. It also seems to work fine when I connect it to the AUX input of the sound thingy on my computer.

Notes:

• Plays 8-bit samples in mono only. Extrapolation aka oversampling can be used to improve the output.

• Uses GCLK3 and TC4, affects TC5.

• The values of the capacitor and resistor I use have not been calculated; they just happened to be the ones lying around within reach and their values seemed close enough for this.

• Sound quality may improve a bit if you add a low-pass filter to get rid of the "steps" in the output. Extrapolation does make them smaller, but they are still there.

• If you have an Arduino 33 IoT, playing the sound with the example will start when you tap your breadboard, or hit your table (Tilt!). Other Arduinos will just loop the sample with a short pause inbetween (I hope).

• The example will load very slowly in the Arduino IDE, because there is a large sample array in it, and the Arduino IDE isn't very good at loading large programs quickly.

• Only tested on the Arduino Nano 33 IoT, and this is an early version; YMMV.

Thanks:

Thanks go to Martin L. for explaining timer-related esoteric and dark stuff on the forums.

Usage:

Include: #include <AudioPlayer.h>

In setup: DACSetup(f, n); for f Hz playback with n times oversampling (n = 1, 2 or 4).

To play audio: playSample(arrayname, arraysize);

Also see the code.

If you feel like donating for this, you can do so here: http://ocrdu.nl/donations .

arduino_samd21_audio_player's Issues

Adafruit Trinket M0 plays sine1kHz but not other examples

Using an Trinket M0 (which is an SAMD21) I can play the sine1kHz array just fine.

However, neither HAL nor Eurythmics plays.

I tried truncating HAL to be the same size as sine1kHz, but that doesn't work either.

Looking at the oscilliscope I also don't see anything resembling a waveform. Pin A0 appears to either be in HIGH or LOW, nothing in between (as you would expect for DAC).

Not sure what else I can do to troubleshoot. Thoughts?

Play samples from SPI Flash memory ?

Is it possible to recover samples from data structures other than const uint8_t ?
Because it tries to play samples from Flash memory on XIAO's SPI interface but it doesn't work.
You wrote a very nice library.
Sorry for my English.
Regards Jan Czereśnia.