The quest to a portable Uzebox - update!

Topics regarding the Uzebox hardware/AVCore/BaseBoard (i.e: PCB, resistors, connectors, part list, schematics, hardware issues, etc.) should go here.
User avatar
uze6666
Site Admin
Posts: 4487
Joined: Tue Aug 12, 2008 9:13 pm
Location: Montreal, Canada
Contact:

Re: The quest to a portable Uzebox - update!

Post by uze6666 » Thu Oct 25, 2018 12:09 am

nicksen782 wrote:
Wed Oct 17, 2018 4:32 pm
SD support is pretty strong now (especially with the new bootloader.) What if WiFi settings could be stored in a text file and read from there instead? This way you could adjust wifi settings without the need to recompile the program. Perhaps even a separate file per game? Or even just integrate it into the game's data file if applicable. Just a thought.
That's an interesting idea for default options like UART speed and most importantly wifi password though, I'm not sure I like the idea of having that password in clear in a file. That said, it would remove the need of a setup tool which is nice. Would cost of a bit of parsing and setup code for games and a bit more for games that don't need the sd card. I still do think games should be able to setup things differently per game. Need more thinking!

Also, I've been moving slowly lately as I have a little one now that take a lot time! :) The good news is the pcb is fully functional as I've tested the SPI ram, esp8266 and audio section. The only minor "snag"I found is you can hear very faint static in the audio when the esp8266 is transmitting. :| Could be a lot of things since I'm no analog engineer. What is weird is the static is the same level weather the volume is max or completely off! In any case it's totally unnoticeable with music. So next step is to publish everything. Hope to be able to do that this weekend.

User avatar
uze6666
Site Admin
Posts: 4487
Joined: Tue Aug 12, 2008 9:13 pm
Location: Montreal, Canada
Contact:

Re: The quest to a portable Uzebox - update!

Post by uze6666 » Thu Oct 25, 2018 1:58 pm

Another quick update. I reassembled the board in the case hoping the static would be less noticeable but alas no. Seems even a bit worst. :( Not to my standard of quality I'd say the least. So I'll need to do some hacking and testing trying to externalize the esp8266 to a breakout add its own regulator, more filtering, choosing a better ground point etc. Perhaps just moving it away from the audio section will help.

CunningFellow
Posts: 1196
Joined: Mon Feb 11, 2013 8:08 am
Location: Brisbane, Australia

Re: The quest to a portable Uzebox - update!

Post by CunningFellow » Thu Oct 25, 2018 8:51 pm

The noise might be intentionally radiated from the antenna and not GND related.

Your input to the Audio section - which I assume is an LM386 - looks like signal goes through an RC filter then a pot.

This is possibly going to be a fairly high impedance point for noise to get in. Try adding a short 100mm wire to the input of the LM386 and see if the noise gets worse. If this little test antenna does make things worse you know what direction to go in to fix the problem.

Moving the ESP further away to the other side of the PCB would help in that case as would having a voltage follower in the audio section. Or if you are going to have to add an 8 pin package there make the filter an active one with a voltage follower on the output.

User avatar
uze6666
Site Admin
Posts: 4487
Joined: Tue Aug 12, 2008 9:13 pm
Location: Montreal, Canada
Contact:

Re: The quest to a portable Uzebox - update!

Post by uze6666 » Fri Oct 26, 2018 9:11 pm

CunningFellow wrote:
Thu Oct 25, 2018 8:51 pm
The noise might be intentionally radiated from the antenna and not GND related.

Your input to the Audio section - which I assume is an LM386 - looks like signal goes through an RC filter then a pot.

This is possibly going to be a fairly high impedance point for noise to get in. Try adding a short 100mm wire to the input of the LM386 and see if the noise gets worse. If this little test antenna does make things worse you know what direction to go in to fix the problem.

Moving the ESP further away to the other side of the PCB would help in that case as would having a voltage follower in the audio section. Or if you are going to have to add an 8 pin package there make the filter an active one with a voltage follower on the output.
Thanks for the tips, will try those and report. I've attached the schematic and board for those who would like to see if something obvious could be causing the issue or give me more tips on how to solve it.

Edit: I've put the module away using the previous pcb version which had a header for that and it's about 20 cm away from the audio section now. Still clicks. Adding the 100mm wire on pin 3 didn't make the clicks perceivable louder. I'm wondering if it power related. Perhaps need it's own regulator and more decoupling caps.
Edit 2: Hooked the scope and I see power dips by about 250mv when the 8266 is transmitting. That's the culprit, I have hooked the 8266 to an offboard source to see what happens and sure enough all the clicking is gone. :P Just need to stabilize the power now.
espstatic.jpg
espstatic.jpg (151.67 KiB) Viewed 2471 times
Attachments
Uzebox Portable V2.zip
(208.29 KiB) Downloaded 81 times

CunningFellow
Posts: 1196
Joined: Mon Feb 11, 2013 8:08 am
Location: Brisbane, Australia

Re: The quest to a portable Uzebox - update!

Post by CunningFellow » Fri Oct 26, 2018 10:56 pm

start by putting an LC filter between the ESP VCC and the rest of the circuit to see if the noise is conducted that way.

User avatar
uze6666
Site Admin
Posts: 4487
Joined: Tue Aug 12, 2008 9:13 pm
Location: Montreal, Canada
Contact:

Re: The quest to a portable Uzebox - update!

Post by uze6666 » Fri Oct 26, 2018 11:13 pm

CunningFellow wrote:
Fri Oct 26, 2018 10:56 pm
start by putting an LC filter between the ESP VCC and the rest of the circuit to see if the noise is conducted that way.
What values would you recommend?

Edit: I made a small breakout board with a separate regulator and plenty of caps (100nf, 220uf, 10Uf) to no avail, I still get dips in the voltage. I think the powerboost has a hard time with it. So I had the idea of connecting the esp8266 directly to the lipo battery pin since it surely can surely handle that. Sure enough, no more clicks. So that seems like a pretty good option specially since LIPO are pretty much dead at 3V and the esp8266 can go as low as 2.5V so we should be just fine for the whole battery life. My LIPO starts at 4V but doing my tests today I put 5V by mistake directly on it for a couple of hours and it handled it just fine. It was and ESP-12F though, so maybe those are tougher. :) A couple more tests tomorrow and will have to do a, hopefully, last pcb rev. Then I'll call it a day.

User avatar
uze6666
Site Admin
Posts: 4487
Joined: Tue Aug 12, 2008 9:13 pm
Location: Montreal, Canada
Contact:

Re: The quest to a portable Uzebox - update!

Post by uze6666 » Sat Nov 10, 2018 3:48 am

Update time: unsatisfied with the previous revision I worked on yet another one and I really hope it's good this time. I moved the esp8266 much farther away from the amp since as Cunningfellow mentioned it indeed caused interferences in the lm386 when close. This time, i planned a header to be able to place it offboard even further if needed. I also reorganized the lm386 to reduce input traces to minimum in order to reduce interferences pickup. I also decided to drive the esp8266 directly from the battery. At full charge it's a bit over the spec, but hey, it's not the first time we've done that in the uzebox. :)

Fingers crossed it will be good this time. I'll report as soon as I assemble it.
Attachments
PSX_20181109_213000.jpg
PSX_20181109_213000.jpg (214.49 KiB) Viewed 2408 times

CunningFellow
Posts: 1196
Joined: Mon Feb 11, 2013 8:08 am
Location: Brisbane, Australia

Re: The quest to a portable Uzebox - update!

Post by CunningFellow » Sun Nov 11, 2018 9:55 am

good work.

The other thing you can do aside from moving the noise radiator (ESP8266) further away is to lower the susceptibility of the audio amp.

User avatar
uze6666
Site Admin
Posts: 4487
Joined: Tue Aug 12, 2008 9:13 pm
Location: Montreal, Canada
Contact:

Re: The quest to a portable Uzebox - update!

Post by uze6666 » Fri Nov 16, 2018 9:25 pm

CunningFellow wrote:
Sun Nov 11, 2018 9:55 am
good work.

The other thing you can do aside from moving the noise radiator (ESP8266) further away is to lower the susceptibility of the audio amp.
Any concrete suggestions for that?

CunningFellow
Posts: 1196
Joined: Mon Feb 11, 2013 8:08 am
Location: Brisbane, Australia

Re: The quest to a portable Uzebox - update!

Post by CunningFellow » Fri Nov 16, 2018 9:52 pm

I can give more ideas if you post the schematic.

But first thing I would try is the suggestion I made a few posts ago.

Straight after the PWM leaves the ATMega644 have it go through a low pass filter and then a unity gain buffer (voltage follower) before going through the volume knob.

Hopefully your newest spin with the esp moved further away is enough though.

Post Reply

Who is online

Users browsing this forum: No registered users and 7 guests