DigiX SMOKE! (thread should have been here)

[exeng]

Here is a link to the prior posts on this topic. Should have been posting here from the beginning.

http://digistump.com/board/index.php/topic,2546.msg12201.html#msg12201

[exeng]

Pete, RE: Your big project comment...
http://digistump.com/board/index.php/topic,2546.msg12206.html#msg12206

I'm planning to use the DigiX to drive a WAV Trigger to provide a voice to a "kiosky" Robot (stationary). I had been working on voicing, motion detects, button inputs, etc., when I decided it was time to bring up Wifi on DigiX so it could retrieve my Thingspeak info from all my Oaks. You know, pool temp, weather, garage door status and speak it to me. I already have the DigiX robot playing fun startup sounds and even presenting a trivia game, (10 questions with 3 possible answers, with scoring and appropiate responnses). It was all going quite well until the Wifi issue popped up and while trying to figure out why it was not working, I got smoked (I should say it).

Long term plan is to add more sensors (e.g. touch, distance) and displays (RGB, LCD or perhaps TFT). All on hold now waiting for DigiX part. This is why I need so many GPIO's.
Plus I want to put this stuff to use.

EDIT: And yes, I had thought about using other micro as slave devices to asynchronously drive displays, servos, motors, etc. Just haven't figured out how to wire communicate with them (CAN bus?).

[PeterF]

lol... now I regret mentioning the cross-forum posting! 

Anyway, that sounds really cool!  A pair of these 'lil puppies arrived a few days ago, and I still need to actually wire them up and see how hard they are to drive, but it sounds like we're doing some of the same stuff in that area. I got hooked by talking Arduino stuff once I saw a Red Dwarf Tawlkie Toaster project that someone else had done, and then saw some mention of these cheapie DFPlay modules on the Particle forums shortly afterwards!

You see, your problem was you wanted too much...  and the DigiX said NO ;-P As you say, it was probably a connection surge that made it blow it's top  One of the reason I much prefer the switching regulator stuff that has a soft start functionality... to basically prevent this problem. Seem to see it more in commercial stuff than the module stuff for DIY though.

[Solice]

PeterF,

Thanks for the link to those cheap DFPlayers.  I just bought 10, because at that price, I can make throw-away widgets to send to people.  That listing doesn't even come up when I search for DFPlayer.  Thanks!

[exeng]

UPDATE: Well the AOZ1021 buck converter part arrived today and I was very excited to get it down and back to testing. Got it soldered down just fine and it doing it's job based on probing it's in / out pins. However, the SMOKE event apparently also took out the 5V to 3.3V regulator (NCP1117ST33T3G -3V3) without leaving a mark. I've got 5V but no 3.3V and consequently no power to the 3.3V components on the board. So here I sit waiting again for parts. Hopefully that will be the end of the down stream damage.

Gee, I wonder if I have a 3.3V regulator in my parts bin, that's close enough in specs?

[Solice]

If you wanted to try it, you can feed 3V3 into the appropriate pin to try an external power circuit, as long as the ground is common.  When I was mucking with the board, about 200 mA was good enough for most of the time, but I saw spikes up to 600 mA on that line.  Depending on the parts you have available, you MIGHT be able to put two parallel regulators together, hoping the current path doesn't prefer one too heavily due to different binned parts with significantly different resistance.

[exeng]

Yep thought about doing that. I'll give it a try.

BTW, lifted the damn tab pad on the regulator when trying to remove the part (should have been more patient). It's going to be some ugly rework when the new regulator part arrives but I think I can do it.

[PeterF]

Ouch! Yeah, I'd probably try the external 3v3 power before replacing that part, just in case something else important... (you know, like the MCU... that's pretty important!!! :-P) got wiped out as well 

Ah, reminds me of a recent issue we had with a radio... the transmitter section was fine, but the receive section was stone deaf... and since it's a 30+ year old radio, a lot of it's components are obsolete... at it was going to cost 5 pounds plus god knows how much in postage just for one itty bitty surface mount RF four-legged mosfet package... since it was a second hand radio, it was getting a bit too much to be bothered with, especially if it was more than that that had been whipped out by the prior owner... :sigh:

[exeng]

Yeah, don't know if more than 3V escaped the regulator on the output. I hope it died a lonely death and didn't bother anyone sitting the 3.3V rail. Losing my optimism though, as 3.3v in the 3.3v pin lights the pwr LED but I can't really test anything else, and MC gets very warm. It may be toast. I'll know for sure when the regulator comes in.

I'll really miss my DigiX if it's dead. I can handle the $60 loss.

[Solice]

I suppose one last thing you can do just for posterity is to hook up a multimeter in series with your power source to see how many amps it's drawing.  If it's very high, then you may have a shorted or fused part.

[exeng]

Seeing about 1.4A whether Wifi enabled or not. Don't know what a normal current draw would be. Concerned that some decoupling caps are leaking or shorted.

[Solice]

That's about six times more than I'd expect.  Probably a short somewhere, which may have been what fried the regulator.

[exeng]

Putting down a new regulator will most likely confirm that there is more damage than I initially thought there was.  I think I already know the answer.  I may be shopping for a Mega or Due with a Wifi shield. Arrrgh! I'm really going to miss my DigiX, but perhaps I shouldn't have based an ambitious project around a discontinued board.

I wonder if any surge protection, Zener, or slow ramp on the supply voltage would have prevented this?