Improving ESP32 LyraT

Improving ESP32 LyraT
Sorry about the dust

That's a hell of a clickbaity title innit?

I picked up an ESP32 LyraT v4.3 board some time back. It's a dev board from Espressif for developing things like smart speakers which marries up their ESP32 WROVER module with audio DACs and ADCs and that. I never got around to using it for what I'd intended though (someone was using GitHub purely for distributing their proprietary binaries without source code, build/installation instructions, etc) so it's been sat knocking around looking for a purpose.

Recently I discovered the Arduino Audio Tools project via my favourite top-hatted, Swiss-accented hardware chap. The quality of the code, documentation and examples is really good and developer Phil Schatzmann has been incredibly helpful with getting me up and running on a different, problematic board. His library will also handle the LyraT board so I got it out and plugged it in, and was reminded straight away about two annoyances:

  • a green power LED bright enough to burn through steel
  • a requirement to provide power via a second micro USB connector when developing

So I improved the board. The first one was easy, the green LED now has copious amounts of Sharpie across it which brings down the brightness to the point where it's not painful to look at it. (Yes, the current limiting resistor could've been replaced but we're looking at 0402 packaged components and I'm not going there.)

Looking around for a way to fix the second issue, I had a sniff around the schematics and found an unpopulated zero ohm resistor in the power section, bridging between the data USB port and VBUS...

Now, the components on the board aren't labelled with only a few exceptions, so knowing it was R226 wasn't as helpful as knowing I'd be looking for unpopulated pads somewhere, most likely, very close to the connector. In case the photo at the top of this post doesn't give the game away, I found it and, one solder bridge later, I've now got it all working off the one USB lead.