Auto Analog Audio & NRF52840: Now working on non-Mbed cores
Playing around with the AAAudio library
So I finally decided to make the necessary purchase and get myself a relatively cheap oscilloscope, and with that play around more with the AAAudio library. Even with the added view into the output signal and what is going on using the scope, I still haven't been able to figure out what I'm doing wrong with the I2S interface, so for now the audio is not of the highest quality, which is relatively good for voice, but not so good for higher frequency audio signals.
I have, however, made progress on using the non-MBED core for both input and output of audio using the PDM (microphone) and PWM (amp/speaker) interfaces, which opens up more of the capabilities of this device! In the end, once I actually quit working with the I2S interface, it wasn't that difficult getting the non-MBED core to work. This means that AAAudio should work on other devices like the Feather 52840 Express etc, but it hasn't been fully tested yet. The PWM interface can handle ~10-bit audio at 16Khz, and lower at higher sample rates.
It also allows users to adjust between 20khz and 16khz PDM samples now as well!
Users can specify which pins to use for PWM by editing the library src/NRF52840/AutoAnalogAudio.cpp file and specifying the GPIO pin and port numbers, else it defaults to GPIO #5, port 0 for output.
As of this writing, users would need to download and install the library from ZIP directly from here because I will not do a new release for a while. (Still testing and potentially updating the new capabilities)
