Mini receiver/CD player thing using ESP32 and Arduino Audio Tools

[vladkorotnev]

OK, I think this is ready to show off despite some minor issues for the time being :P

This is an internet radio receiver + CD player + bluetooth receiver thing based around an ESP32, using Arduino Audio Tools in some modes!

Many of you may know the cheap IDE CD drive control boards sold on Taobao et al, as well as the countless projects accomplishing the same task — starting with the infamous ATAPIduino, and a handful of PIC-based projects just among those that I've seen.

Back in my childhood I had a crazy dream of building my own CD player, but a CD drive cost a fortune, and a microcontroller development environment a hundred times more. But in this day and age, after getting somewhat hooked on developing for ESP32 I decided to try my hand on a similar project, and crank it up to 11.

Demo video: https://www.youtube.com/watch?v=To1woYCxPkw

What it can do:

• Read the CD Audio TOC from the drive (I tried making an ISO9660 VFS driver too, but because I copied the I2C schematic from ATAPIDuino, the speed is too low, so it's useless)
• Request the drive to play/pause/seek/etc — either in sequential or shuffle mode (no program playback yet). The audio is then fed to a Wolfson WM8805 and a PCM5102 DAC with a DC-coupled output. I don't believe in differences in digital audio gear sound, but it does sure sound fancier than my Sony CDP-790 :P
• If the drive is a changer (e.g. Nakamichi MJ-4.4, or TEAC CD-C68E) it can also ask it to change discs, and once a disc finishes playing it will start the next one in the stack. Albeit my C68E has been acting up so this is glitchy/untested for the time being.
• Fetch metadata for the track names and artists using CD TEXT (if the drive supports it), or MusicBrainz, or CDDB (yes, I used the real libcddb from 2005 lol)
• Cache that metadata in flash with compression, so you can probably fit your whole collection (or remainder thereof) in the littlefs partition
• Display karaoke lyrics from multiple different repositories in sync with the music playing and with auto font sizes (latin/cyrillic: 16 and 8 px tall, japanese: 16/12/8px tall)
• Send now-playing status and scrobble the playing tracks to Last.FM (using login+password auth)
  
• Receive internet radio stations in MP3 and AAC formats, with up to 6 presets
• Receive music from a cellphone over Bluetooth (SBC only) and control it (play/pause/stop/volume)
• All of this is controlled either from a 8-button front panel, or from a Playstation 2 DVD remote (chosen because I find a whole bin of them in every HardOff I go to, and they feel nicer than the "card remotes" you can buy cheaply online while being useless for 99% of people)

Also someday I wish ("plan" would too tough of a word in the current state of me) to:

• Do a new board revision with an IDE bus that's faster than an average FDD back in the day :P maybe using an SPI based bus expander rather than I2C
• Consequentially, reading MOD/XM/S3M/IT music, and maybe MP3/M4A/FLAC too, as well as omitting the requirement for a digital output on the drive itself (and maybe being able to use SATA/SCSI drives through an interface adapter, huh!)
• While revising the board also slap a chip that does analog radio (AM/FM+RDS)
• ... and a hardware MP3/AAC codec just to make things easier down the line
• then maybe an amp module et voila, an opensource stereo system from the 90s but in 2020s!
• and maybe find out why some drives work worse than the others... I mean, they all work equally well in a PC, right! And look what a pile I had to try to make it work, a completely sane person's desk indeed:

Audio Tools is used for the internet-radio and bluetooth side of things. While in theory the circuit also allows for capturing the CD sound into the ESP32, I haven't yet found a use for that.

Many thanks to Phil for bearing with me during debugging the internet radio side of things, it was a bit of a nightmare for both of us figuring out why things aren't going as smooth as they should in theory.

You can find the source code here: https://github.com/vladkorotnev/cd-player/tree/master/firm