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problem/question re Mini Sound+Amp+LipoBackpack
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Please be positive and constructive with your questions and comments.

problem/question re Mini Sound+Amp+LipoBackpack

by NerdNoob451 on Mon Jul 06, 2020 2:11 pm

Apologies, noob user, hoping someone can confirm or point me in the right direction. I've got a sound project that is largely complete, have a specific behavior that isn't ideal, but may be 'as designed'.

The project is retrofitting sound effects into a prop (specifically, a Matrix Pulse Rifle from the movie Aliens). I started with the Adafruit Audio FX mini sound board (2MB, no built in amp), mono 2.5W Audio amp and small speaker. For initial prototyping I used an external USB battery for power, and for connecting to PC to load the audio files I wanted. As I progressed, I couldn't fit the external USB battery anywhere inside the project and have it reachable, so picked up the Ada 1200mAh Lipo. I was going to hardwire it but then discovered the Tricket LiPoly backpack was compatible with the sound board, and would do automatic switching from charging over USB to powering from the LiPo. This configuration seemed almost ideal, until I ran into this:

With the LiPo JST connected to the backpack (which is soldered piggyback on the sound board), yes it CHARGES as expected (draws FROM USB battery when connected, and powers from battery when nothing on USB), but it does NOT communicate with PC as a USB device when the LiPo is connected to the JST on the backpack. I have to disconnect the batter to get a PC to recognize the sound board as a USB device again. This is highly undesirable from a logistics viewpoint, as it will mean disassembling a complicated build every time I want to adjust the sounds, vs the original intent of being able to just tuck away the USB cable, use as needed for both charging and programming. I've been thru the product pages on all three boards, and tried searching the forums, can't see anything definitive one way or the other. Does anyone happen to know if this is intended? That mounting as a USB device is disabled when LiPo attached? If I hard-wire the LiPo instead of going via the JSP backpack, what happens?

Worst case, I've order the JST extension cable with on/off switch, which I pretty much need with this configuration anyway, otherwise it will slow-discharge between uses. But I'd still like to know the 'expected' behavior for future troubleshooting.

Thanks tons!

NerdNoob451
 
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Re: problem/question re Mini Sound+Amp+LipoBackpack

by dastels on Tue Jul 07, 2020 11:53 am

How do you have the backpack connected to the sound board?

Dave

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by NerdNoob451 on Tue Jul 07, 2020 3:38 pm

Soldered on piggyback, via long header pins (pic attached). Connections are:

Vin to 5V
Gnd to Gnd
Bus to BAT

I then carry GND and Bus/Bat over to the amp.
Attachments
LiPo_backpack.jpg
LiPo_backpack.jpg (659.38 KiB) Viewed 50 times

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by dastels on Tue Jul 07, 2020 5:49 pm

You have Vin and BUS swapped. The backpack should go on the top of the board.

Vin to BAT
Gnd to Gnd
BUS to 5v

Dave

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by NerdNoob451 on Tue Jul 07, 2020 8:37 pm

Doh! Thanks tons! I had prototyped this config, and I guess I mistakenly assumed it was 'correct' because it 'worked' in the sense I could power the system and trigger the sounds. It never occurred to me I could get the same results with the board flipped. And when dry-seating it that way, the currently unused fourth hole (half of the boxed pair that I will next use for on/off switch) sits on top of the header pin from the UART TX on the sound board, which seemed to further indicate it didn't seat that direction. I'm not using UART at all, so I'll just trim that pin off.

Time to try some solder wick, I guess. ;-) A pain, but also means I can also now solder the jumper for 500 mAh charging. Thanks so much for the fast response. Apologies if that was an 'obvious' moment. Much appreciated!

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by dastels on Tue Jul 07, 2020 9:46 pm

No worries. It happens to all of us.

Dave

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by NerdNoob451 on Sat Jul 11, 2020 1:22 pm

Hey again. :-) So, backpack is flipped, but now I have the reverse problem. Powers up fine from USB battery, shows voltage on the female JST on the backpack, and on the Lipo battery where the power leads connect. But the battery doesn't seem to be taking a charge. Left a USB battery connected all night, showed the red charging light active, and slight illumination of the Done light (which the docs say is to be expected). Next morning, no power, USB battery dead, but also no power to the board from the battery. I have an on/off switch wired in, and I broke the associated connection on the board per docs. When I switch the connection to off, the red charging light intensifies slightly, the faint green Done light goes out, and no voltage detected on the backpack JST. It is detected and mounted as a USB device fine now with the battery connected. But given the battery doesn't seem to be taking a charge at all, not sure that's a confirmation.

I've read the Adafruit batteries are a proprietary config (reversed polarities), but both the backpack and battery are supposedly Adafruit. I bought them thru Amazon, so I'm wondering if the Lipo was a knock off/other brand? It has the same number as on the Ada site, LP503562, but it also has 'PKCELL' printed on it, which I don't see on the image on Ada (https://www.adafruit.com/product/258). But I do see PKCELL on the listing on DigiKey, and they are the recommended reseller (https://www.digikey.com/product-detail/ ... (Secondary)&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Battery%20Products&utm_term=&utm_content=Batteries%20Rechargeable%20(Secondary)&gclid=EAIaIQobChMIqsrV2tfF6gIVxkXVCh0MJgISEAQYASABEgJWqvD_BwE). Or maybe I fried the battery?
Attachments
IMG_8504.jpg
IMG_8504.jpg (649.05 KiB) Viewed 44 times

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by dastels on Sat Jul 11, 2020 5:22 pm

I don't think Adafruit batteries are proprietary or reversed (I could be wrong). They're just consistent with the boards they plug into. That was the first thing I checked from your photo and it looks as it should.

Have you tried a different LiPo battery? I am wondering whether the charger or battery got damaged while the backpack was connected backwards.

Dave

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by NerdNoob451 on Sat Jul 11, 2020 6:51 pm

Unfortunately no other lipo at hand at the moment, this was my first project of this type (closest was a ForceFX saber hilt LED retrofit, that's why I had the soldering set-up, thought I'd give this a shot). I've just ordered a second set of everything, soundboard (with amp built in this time), backpack, and a couple more lipos, direct from Ada, with 3day express shipping, but I can't quite tell from the website if this will be delayed due to covid. Worst case, I can swap out each component in turn (and can use the spare bits for next project).

I may try another 'made by Adafruit' lipo sold on Amazon in parallel. But I don't think it's the battery, I just slipped a couple breadboard connector wires into the battery JST so I could take a direct reading, looks like its sending 4V. So seems like it has to be something on the backpack? GND/Bus circuit is 4.94V. With USB battery unplugged but lipo plugged in, its dead. So maybe the backpack not switching back to 'draw from battery'?

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by dastels on Sat Jul 11, 2020 9:16 pm

Shipping turnaround seems to be in good shape now.

It's worth double checking battery JST polarity. Especially if they aren't from Adafruit.

Dave

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by NerdNoob451 on Sun Jul 12, 2020 2:48 pm

I checked the polarity by connecting the USB battery to the sound board, then measuring at the backpack JST pins. Reads 4.3V with the red multimeter lead on the 'left' pin looking 'down' at the backpack from above the JST housing. That's also where red lines up from the ridge enforced by the battery-side JST connector. And reads negative 4.3V if I reverse the meter leads, so seems 'right'. I also tried manually connecting the battery to the header pin connecting soundboard Bus to backpack 5V (which then carries over to the amp/speaker), plus GND. That works, powers the system, operates fully, including active Red charge light on the backpack. So battery is definitely charged and distributing. Conversely, connecting directly to header pin connecting sound board Vin and backpack Bat, plus GND, does nothing. Nor does connecting to the +/- contact points that connect the JST housing to the backpack. It's like the power flow is 'one way only'

So I'm leaning towards it being an issue with the backpack. Guess I better start de-soldering again. :-)

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by dastels on Sun Jul 12, 2020 6:29 pm

The backpack would be my first suspect since solid state electronics tend to be the most delicate when bad power is concerned.

Dave

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Re: problem/question re Mini Sound+Amp+LipoBackpack

by NerdNoob451 on Sun Jul 26, 2020 1:08 pm

Just to close out on this, many thanks for all the help! Got it sorted finally. Tried new backpack, didn't solve it. Tried new sound board, didn't solve it. Swapped them both out, now working perfectly. I definitely did some damage to one component or maybe both, but still not sure which. :-) Will try to narrow it down for next project, hopefully one or the other is still usable.

Overall project results are SPECTACULAR, couldn't be more pleased with these products. Took a stock airsoft replica, converted to digital sfx, one to 'real' trigger, others to new internal and external momentary switches, runs off internal lipo and charges/updates sounds by USB cable that tucks away. Total elapsed time was vastly due to my own ignorance/learning curve (disassembly, solder/de-soldering). With the Ada products, I could do this again, knowing what I know now, in probably a couple of hours. Will be trying a few more projects at this level, improve my techniques and understanding, then look to get more ambitious.

Thanks again!

NerdNoob451
 
Posts: 7
Joined: Mon Jul 06, 2020 1:34 pm

Re: problem/question re Mini Sound+Amp+LipoBackpack

by dastels on Sun Jul 26, 2020 2:33 pm

Excellent! You should consider showing it off on the weekly Show&Tell stream/show.

Dave

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Joined: Tue Oct 20, 2015 3:22 pm

Please be positive and constructive with your questions and comments.