DigiX SMOKE! (Dead R.I.P.)

[exeng]

We'll if you have been following this thread: http://digistump.com/board/index.php/topic,2547.msg12236.html#msg12236

you know that I have been trying to resurrect my DigiX by replacing some toasted parts. The buck converter was taken out in a puff of smoke and replacing it only revealed that the 3.3v regulator suffered damage too. While waiting for that part, I've injected 3.3v on the 3.3v rail to no avail. I see a dim power led, about a 1.4A draw and a very hot Amtel MC. So after sleeping on it (not literally), I've decided to call it dead. There's no need to solder down a new voltage regulator. I'll just be once again as disappointed as I was when the new AOX1021 did not fix the problem.

So you ask, how could this happen with nothing attached and how can I avoid this demise? Well, in doing a post-mortem and reflecting on what I was doing at the time of SMOKE, I had switched to a 12V supply at the barrel jack but also had USB connected for uploads. Couple of things most likely contributed to the demise of the DigiX. I suspect that with the USB connected, the soft start feature of the AOX1021 was basically overridden. The PS that I used was rated for 12V but actually shows 16V on a meter at the jack. So, I'm thinking that the higher voltage / in rush current damaged the AOX1021 allowing it to pass 16V to the regulator and on to the 3.3V rail before completely shutting down. And what critical component sits on the 3.3V rail? Hence, death of the DigiX. At least that's my theory.

It's with great sadness that I will morn the loss of my DigiX. My only solace  is knowing that I helped Erik in some small way with his DigiX Kickstarter campaign.

I hope this helps someone else in some small way to avoid the same end. So, into the parts bin ya'go my fair DigiX.

So, what should it be? Mega, Due, or is there a working DigiX laying around doing nothing these days?  I need pins, memory and wifi.

[Solice]

It's really a shame, since the DigiX was really the mother of all microcontroller development boards of its class.

If you have an Oak, you can use a two microcontroller solution.  Have the Oak handle wireless communication, and have it also communicate to another microcontroller that does most of the work or utilizes the pins you need for other things.  If you need more pins than an ATmega328, an ATmega1284 with MightyCore would be my choice.  Otherwise, you might find that an Arduino Mega clone device is cheap enough and with more pins (and more flash).  If you need smaller and are willing to pay ten more bucks, a Teensy++ 2.0 or Teensy 3.5 might be what you're looking for.

tl;dr
I'd go with an Arduino Mega (or clone) + Oak or ESP8266 module, or swap out the Mega for a Teensy++ 2.0 or Teensy 3.5 if physical dimensions are an issue.

[exeng]

Solice, Thanks for the advice on the choices.

Given the number of sensors / types of displays I'm considering, size of code and the need for Wifi, I basically decided that the DigiX was the perfect candidate to develop on and would not limit me while developing. Once done (or at least at a point where I could more closely predict my needs for pins and memory), if it where possible to shoehorn into something smaller than I would, but the DigiX was the ideal development platform for prototyping.

It will be sorely missed. Too bad, Erik is not producing any these days.

[Solice]

It's not an issue of Erik not making this anymore.  The microcontroller that this was based around was discontinued by Atmel    As a result, I hold onto my DigiX's like they were my children.  I have named them Yumyum, Clyde, and Sue.

[exeng]

That makes me even sadder. Treat them well.

[PeterF]

Yumyum? I hope that one is doing something food related! :-P

So when will the funeral be exeng... or will you just finish the half-commenced cremation? 

I just powered my DigiX via the 3v3 pin with a stable 1A capable supply, and it appears that the WiFi side can't be powered that way... it was drawing somewhere around 100-120ma @ 3v3, and didn't connect to my router. I then powered it via USB (so 4.7-5v) and it is now pulling 180-220ma (oh wait... that may also be the onboard led blink... is running the blink sketch IIRC and is in time with the surges).  Pull the WiFi enable jumper, and it is 130-170ma). There was a minor drop in power consumption when I tried the same when powering via 3v3, but only 10-15ma, so not sure what to make of that.

Maybe solice can help me with this though, since he has a number of DigiXs in captivity... does your MCU get hot? Like, put your finger on it after it has been running for a few minutes and it is noticeably hot? And even if you shove a heatsink on it, it still does a good job of warming the heatsink up? Do you know if it is possible to lower the clock frequency (easily!) to reduce heat/wasted power? That was the main think that made me decide to use a teensy / Atmega328 + Oak for one or two other projects instead of the DigiX... I wanted to use it for the wifi + nrf + oodles of memory, but then it just seemed a power hog.

[Solice]

Hrm.. about an hour or so of being on, and it gets up to 95 F (35 C) according to the IR gun.  Not dangerous, but certainly shows there's some wasted power somewhere.  It seems that the warmest part is the MCU itself, so I'm not sure what to do about that.  I'm not well read on this chip.  It's an Atmel chip, so there could be fuses.

I was going to look this up for you, but the datasheet appears to have hundreds of pages, and it's getting late.  Good luck! http://www.atmel.com/ru/ru/Images/Atmel-11057-32-bit-Cortex-M3-Microcontroller-SAM3X-SAM3A_Datasheet.pdf

[PeterF]

 

Well, as long as yours is nice and toasty also, then all's good... I got ambient of temperatures of 33C at the moment... so that won't be helping!   I was hoping to avoid the datasheet (at 1459 pages it's a wee bit longer than the 660 of the Atmega328  ... which is long enough for me ), but looks like I'm out of luck if I do want to drop the temp... as you said... there should be a fuse setting, or hopefully a runtime function/variant possibility so it can clock up and down as needed by the application (not that I have had much luck seeing if there is something for the Due, let alone the DigiX).

Thanks for that... I'll probably keep on with the AVR or Teensy + Oak approach then for that sort of low power + WiFi capability

[exeng]

PeterF... you ask:

So when will the funeral be exeng... or will you just finish the half-commenced cremation?

Well, as soon as I stop staring at the board and imagining lifting the MC and putting down a new one. Probably not cost effective as the MC is about $10, and a ChipQuick removal kit is about $15, all Sans shipping. Then there is the skill required to pull this off (no pun intended), and then successfully put down the new MC. Finally, don't know if the MC needs any boot loader programming. But can't help dreaming about it.

It's really difficult to let my DigiX go.

[PeterF]

Well... what have you got to lose (other than a little bit of time and money)? :-P It might be worth it just for the experience.

As far a bootloading... IIRC, because this is a SAM3X based board, the bootloader is pre/hardcoded into the ROM at the factory (SAM-BA), so it shouldn't be an issue.

@Solice: I meant to mention earlier - the DFPlayer modules seem pretty good... I'm just using them for looped music playback so far, and they sound ok, and they do have some peculiarities to work around (such as any serial information requests made whilst they are playing will make the audio skip for a moment whilst it processes the data :-/), but you can relatively easily work around that by waiting for it to gell you want's going on, not the other way around... I could see a Digispark controlling them without too much drama... making real compact throwaway designs

Edit: I don't know if either of you find this interesting... it popped up in today's news feed, and is probably the smallest SAM/ARM development/breakout board I've seen so far

[exeng]

Well I could not just let go of my DigiX. I'm in the middle of trying to bring it back to life. Keeping my expectations low but here is a progress report:

As you may know I've already replace the buck converter that released the smoke. I works.

The 3.3V regulator was also damaged so it's off the board with a replacement ready to go. Unfortunately in my haste I lifted a pad so you will see some ugly rework on the board but it Ohms out correctly.

Next step is to see if the removal of the MCU also removed the high current draw which would lead me to believe that the short was in the MCU. Fingers crossed.

Now the hard part... getting the new (fine pitched) MCU down on the board. But before that, I will do some probing to make sure the short is gone and perhaps try to power the radio separately and probe around it's status pins.

Think good thoughts and wish me luck.

[exeng]

Yes! It's alive, it's alive, it's.... alive!... Well, almost.

With 3.3v on the 3.3v rail and the damaged MCU off the board, the short is gone and the radio shows up as an AP.  Almost there...

Now the hard part. Can I get the new ATSAM3X8EA-AU soldered down without a hitch?

[PeterF]

Apparently (so I hear), it's pretty easy with solder paste... but I've never tried or used it... so I will be interested to see how you got with this 'lil sucker... there's only... half a zillion legs to solder on! Sounds promising... fingers crossed that Dr Exeng manages to revive the patient

[Solice]

I have a somewhat unorthodox way of dealing with this, and it'll make you puke.

Just.. put the package in its correct place on the board, and solder bridge all over the place.  Just dump molten solder on the legs on one side so it adheres to the pads, and then solder pump off the excess.  Repeat for each side.  If you're willing to wait a day or two, I can have photos of what I'm talking about.

[exeng]

 Solice,

I'm just savoring the successfully removal of the MCU. Like a fighter training for a big fight, I'm trying to get myself mentally ready to tackle the job. So yes I'm willing to wait. I may even clean up the old MCU pins (should be easy to get all the Chip Quick solder off) and practice on some other scrap board with the same pitch if I can find one.

Yes, I would be willing to wait to see the method you suggest. At this point I'm looking at different ways to tackle this.

Pete, perhaps Dr in training.