nrf: Add i2s audio output #2127
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Testing performed: I used a Particle Xenon with a HDA1334 I2S DAC. I played a variety of mono 16-bit samples at 11025 and 22050Hz nominal bit rates. With this setup, all the 11025Hz samples sound good. I tested play, pause, and loop functionality. During some runs with 22050Hz samples, there were glitches. However, these may have only occurred during runs where I had set breakpoints and watchpoints in gdb. I also tested with a MAX98357A I2S amplifier. On this device, everything sounded "scratchy". I was powering it from 5V and the 5V rail seemed steady, so I don't have an explanation for this. However, I haven't tried it with a SAMD board.
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I had used those MAX98357A amplifiers at work and had problems with them at the beginning, by any chance did you captured the I2S traffic with a logic analyzer? My problem was because I didn't removed the bit clock before removing the LRClock (WSCLK). |
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@C47D the "scratchy" audio with MAX is while a sample is playing, so I don't think this is the cause. However, I'll attempt to capture a scope trace of the end of playing and look for problems. |
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@jepler Noted, I did work with an STM32 microcontroller on that project and had to use double buffers to play the audio, didn't took a look at your implementation, maybe it's different for the Nordic device, which I'm not (yet) very familiar with the I2S and DMA peripherals. |
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@jepler what's it look like with a sine wave playing? you can put an RC filter on the speaker outputs to scope it - also maybe post a pic of your setup? |
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Overall nice work! I tested it using the UDA1443 and the nrF52840 FeatherWing with the sine sample: https://learn.adafruit.com/adafruit-i2s-stereo-decoder-uda1334a/circuitpython-wiring-test
I did the same test to compare with the Feather M4 and it did way worse. I could hear the tone but it wasn't as loud or as clear as the nRF. So hopefully you don't mind working on I2S. :-)
Just a couple code comments and then it should be good to merge. Thanks!
.. based on some tasks I found that caused stuttering:
# Test SD and printing
while True: os.listdir('.')
# Test bulk I/O
while True: len(open('somefile.wav', 'rb').read())
Each of these tasks *WAS* worse and I am improving them in a separate
PR by adding RUN_BACKGROUND_TASKS to them.
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@tannewt I have attempted to address your review comments. Thank you! |
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I've been having problems with I2S on the Feather nRF52840 Express running CircuitPython 5.0.0-alpha.4-260-g2b02750f1 (2019-10-26.)
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Testing performed: I used a Particle Xenon with a HDA1334 I2S DAC. I played a variety of mono 16-bit samples at 11025 and 22050Hz nominal bit rates. With this setup, all the 11025Hz samples sound good. I tested play, pause, and loop functionality.
During some runs with 22050Hz samples, there were glitches. However, these may have only occurred during runs where I had set breakpoints and watchpoints in gdb.
I also tested with a MAX98357A I2S amplifier. On this device, everything sounded "scratchy". I was powering it from 5V and the 5V rail seemed steady, so I don't have an explanation for this. However, I haven't tried it with a SAMD board.