Update time! I'ts been a long time, been quite busy with those
other things in life
but was regularly working on it. So happy new year to all!
Well, rev 1.3 didn't work so well. The idea of plugging the 8266 directly on the battery kinda work when the battery was getting low (under 3.5V) but I fried the module when the battery was fully charged at 3.7V+.
But at least when it worked, this totally solved the clicking problems. It really seems the powerboost module could not fully handle those current pulses required when transmitting.
Anyhow, went back to the drawing board and put the regulator directly on the battery instead of piggybacking on the powerboost. Since a dead battery is about 3V and the ESP8266is stabled at ~3.1V (but not fully at 3.0V after testing), I changed the 3.3V regulator for a 3.1V one. ESP8266 and SD works fine and no more clicks on the audio.
Also updated some little things here and there (like replacing that expensive switch) and added two optional tactile switches to help flash the 8266. Pretty happy with it and after all the expenses of the previous revs, I'll call this one done. I'll publish averything so if anyone wants to improve, it's all yours.
I'm not sure of the function of C14 in that circuit,
When I was trying to improve the noise issue I saw on some site a guy that said it could improve noise pickup immunity or something like that. So sure it really helps but I decided to put the footprint anyway just in case. It much prefer to have empty/optional footprints than have to order another batch of PCBs if it ended up being required. I'll do all my tests and if really not required, I'll remove it from the design.
Why are you using this circuit for the LM386?
Does it really works fine?
I compiled all the design notes and examples I could find and it gave that. Now, yes it works fine, though the noise level is a bit noticeable at mid-full volume, probably because of the noise on the power line due to the powerboost and also the remaining ripple out of the PWM DAC. BTW, speaking of the powerboost noise, it conveniently happens that the LCD module board actually filters out a LOT of it for some reasons!
Building a dockingstation for the tv where you can put your portable uzebox in it in order to charge it AND play the games on tv
It's a neat idea. Initially I wanted to have a simple A/V jack to enable it to be plugged in a TV directly. But I decided against it. First, I was running out of space and then, I would have to cut power to the LCD PCB to save power. But then the noise filtering mentioned above would also go away and result in lots of noise in the speaker. A fully docking approach would be nice but at some point, just like in software deveopment, you have to control scope creep if you want to deliver anything
Now to printing the updated enclosure.
btw, on the pic, the screen shows ASCII Starwars streaming on WIFI from the Telehack telenet site. The whole thing runs at 115200 bauds without skipping a single byte.