Loud ESP

Portable, open-source, ESP32-powered audio-development platform with a touchscreen and support for Bluetooth & Wi-Fi connectivity

Jun 28, 2023

Project update 6 of 7

Working on a New Revision

by Andriy

While waiting for funds

While waiting for funds transfer, I took some time to review few remaining issues with Loud-ESP boards. In this new revision, are not talking anything too major of course in terms of changes, just some small improvements.

Touch IRQ pin out, Battery charging status in

I was cruising through Hackaday pages when one article by Dmitry Greenberg caught my eye. He did extensive writeup on the TFT screen, just like the ones that I use. One important observation that he captured, is that IRQ pin on these touch screens is quite useless due to a noise it produces. Since I’ve used all the pins the ESP32 had, and still have a few ideas I’d like to implement, I happily sacrificed IRQ to add battery charging state input. So now it is not only possible to monitor battery voltage using built-in ADC, but you can also monitor if it is charging or not. Code has been updated accordingly. {loud-esp-post-update}

DAC configuration changes

Another change that I’ve decided to incorporate came out of a few small projects that I did in the meantime. What I found is that most of the time audio output is too loud, when it comes to making notification-like sounds. Alternatively, when dealing with music audio, it’s better to vary volume of course depending on the conditions and the mood. The latter had to be addressed in software volume control, but for more generic use cases I decided to lower down the default gain to a reasonable +9 Db, while jumpers on the back allows you to change that if you need to in the range of +3 - +15 Db. Another jumper allows you to enable mono sound.

For the same reason, I decided to lower DAC voltage down to 5 V (down from 5.5 V), and give each channel an individual boost converter. This should help stability on higher volumes and 2-4 Ohm speakers (A bit out of spec for the DAC, but you don’t complain about salvaged speakers, do you?)

Revision F and production batch

A few more cosmetic improvements were added on the way, and revision F has come out into the daylight. I did some testing, and all looks good. Production batch has been sent to production, so hopefully all orders will be delivered right on the schedule.

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