I am currently following this tutorial on building a Simple Audio Player for the Arduino. I was about to finish the circuit only to realize that the required board is an Arduino Due and I have the Uno.
Because the Uno does not have its own DAC port, I was wondering what other options are available for me to accomplish the same thing while keeping the circuit as similar to the one listed in the tutorial.
Thanks
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What's a Duo? Never heard of an Arduino called a Duo before...Majenko– Majenko2017年03月16日 20:49:28 +00:00Commented Mar 16, 2017 at 20:49
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My bad. I fixed it.User 5842– User 58422017年03月16日 20:51:39 +00:00Commented Mar 16, 2017 at 20:51
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Ah, that makes more sense.Majenko– Majenko2017年03月16日 20:52:01 +00:00Commented Mar 16, 2017 at 20:52
3 Answers 3
There are three basic ways of creating a DAC.
The simplest, though roughest, is to use PWM, then low-pass filter it. Not perfect, but rough and ready. Only needs a resistor and a capacitor.
The highest quality way, though slowest for interfacing, is to use an external DAC chip. Fine for low frequency response reproduction, and the linearity is second to none. The MCP4821/2 is a popular choice (SPI connected).
The third option is to build your own DAC using an R-2R ladder. You can make an 8-bit DAC with very fast response by using all 8 pins of a single IO port (such as pins 0-7 on the Uno are bits 0-7 of port D). However the linearity of an R-2R ladder very much depends on how well matched your resistors are.
The R-2R ladder should be buffered with an amplifier of some form before driving a low impedance device like a speaker.
None of them are really great for audio work - for that you need a chip with much more processing power and memory, and a high speed digital audio interface, such as I2S, to interface a proper audio CODEC chip. Personally I use PIC32MZ chips for audio work.
The major problem you have is that the Audio library functions are specifically written for the ARM based Due.
You could certainly add an I2C 10 bit (Mono or Stereo) DAC chip to an Arduino Uno capable of producing stereo signals through an LM386, but you would have to re-write the Audio library to support that functionality on the Uno.
You can probably use the same circuit and the PWM "Analog" output of the Duo (after adding a low pass filter) to play simple tones, and maybe do something on the input side to allow you to change the frequency in response to some user input.
I don't think you'll get the Duo to read from the SD Card and play the audio simultaneously.