[Microbit-Python] Testing Point Documentation

Tue Apr 5 06:20:45 EDT 2016

Hi Andrew - it does sound very similar to my experience. The chip that got
hot was the unlabelled one on the right when looking at the back of the
board. I had assumed it was a power management chip, but it may well be the
USB serial chip you describe. Your descriptions of times (20-30 seconds)
and getting hot on both sides matches my experience.

On 5 April 2016 at 09:38, Andrew Ferguson 500 <andrewferguson500 at gmail.com>
wrote:

> Hi Giles,
>
> I've been in touch with Philip and he'll be sending me a replacement
> shortly (thanks Philip!). Below is a description of my usage of my
> micro:bit (taken from my email to Philip).
>
> Apart from two or three times where it was powered from the official 2x
> AAA battery charger, I've exclusively powered it over USB from the USB port
> on my laptop. (Sony VAIO VGN-C2S running Debian 7 GNU / Linux).  When the
> issue developed, I was powering it from my laptop and hadn't powered it off
> batteries for at least four days. It has never been powered off a mains
> phone charger.
>
> When using it though USB I have always used the supplied USB cable. I am
> not aware of any ESD events, and when not in use I stored the micro:bit in
> the original anti-static bag. I'm not quite sure what you mean by
> 'grounded', the device was plugged into the laptop through USB but the
> laptop was not connected to mains. (If you mean something else, please let
> me know).
>
> The fault occurred whilst I was testing the serial output of the
> micro:bit. It was running a Python program to output some text and wait 1
> second whenever the 'A' button was pressed. I was using the 'screen'
> utility to view the output. ('screen /dev/ttyACM0 115200'). Mid-way through
> the testing, the screen session exited, and I noticed that the power LED on
> the micro:bit had gone off. About ten seconds later I realised that the
> micro:bit was getting hot, and so I unplugged it from the computer.
>
> As far as I can think of there has been nothing else during the use of the
> device that could have caused this. I was the first person to use the
> device (the teacher used one of the other three devices that was sent). As
> far as use is concerned, I have flashed it with various different .hex
> files, but have not used the I/O ports at all so it has not been connected
> to any device which could have caused the problem.
>
> Giles, which chip on your micro:bit got hot? (On mine it was the USB
> serial chip), and how hot did they get - particularly the one that kept
> working? Mine got too hot to touch after about 20 seconds, and after about
> 30 the other side of the board got very hot as well.
>
> Andrew
>
> On 5 Apr 2016, at 09:20, Giles Booth <giles.booth at gmail.com> wrote:
>
> Hi Andrew - very interested to hear about this as I had the same
> experience with 3 out of 4 of my initial teacher microbits. One got very
> hot and died, another got very hot but remained working, a third runs much
> warmer than the 4th unit. The last unit that died was a replacement and had
> only been used in a classroom and never had anything attached to its GPIO
> pins.
>
> Phil Meitiner and BBC have been very helpful, sending me 5 more microbits
> to test - all ok but not tested with actual children, which was when my
> initial teacher units started to malfunction.
>
> Andrew, did you use the GPIO pins at all with yours or just USB?
>
> many thanks
>
> Giles
>
> On 4 April 2016 at 15:46, Andrew Ferguson 500 <andrewferguson500 at gmail.com
> > wrote:
>
>> Hi Nicholas,
>>
>> Ah, my micro:bit does not have a tick, so that's probably the problem.
>>
>> Is there any more info anywhere about this overheating problem? (how it
>> occurs, what can be done to avoid it, etc...).
>>
>> On 4 Apr 2016, at 15:22, "Nicholas H.Tollervey" <ntoll at ntoll.org> wrote:
>>
>> > If it has a tick mark on the front, top left corner (where the "hair"
>> > is), then I believe it's been checked for the overheating problem and
>> > passed. No tick = likely to be an earlier pre-solution version of the
>> board.
>> >
>> > N.
>> >
>> > On 04/04/16 15:24, Andrew Ferguson 500 wrote:
>> >> Thanks, it does get quite hot if left on for more than ~30 seconds.
>> >> (After about 10 it is too hot to touch, after 20 it is very warm on
>> >> the other side of the board. I haven't left it on for more than about
>> >> 2-3 minutes).
>> >>
>> >> This was one of the teacher devices so it could be a slightly earlier
>> >> version than the final student devices.
>> >>
>> >> On 4 Apr 2016, at 15:13, Damien George <damien.p.george at gmail.com>
>> >> wrote:
>> >>
>> >>> There was a problem with some of the microbit's having their USB
>> >>> chip get "hot" but I thought it was resolved.  I'll ask Jonny about
>> >>> it.
>> >>>
>> >>> On Mon, Apr 4, 2016 at 2:44 PM, Andrew Ferguson 500
>> >>> <andrewferguson500 at gmail.com> wrote:
>> >>>> No, the computer does not recognise the micro:bit. If I power the
>> >>>> micro:bit from the 2x AAA batteries nothing happens at all. (No
>> >>>> light, no chips getting hot).
>> >>>>
>> >>>> Hopefully more stuff will be released as Free Software / open
>> >>>> source soon (especially the DAL and the iOS and Android apps).
>> >>>>
>> >>>>
>> >>>> On 4 Apr 2016, at 14:35, "Carlos P.A." <carlos.p.a.87 at gmail.com>
>> >>>> wrote:
>> >>>>
>> >>>> I haven't seen any schematics out yet, that seems to be part of
>> >>>> the documentation that still needs to be open sourced. From the
>> >>>> top of my head I vaguely remember the test points at the back
>> >>>> probably connected to the microcontroller in charge of the USB
>> >>>> communication (and, I assume, the battery controller), so they
>> >>>> might be a programming interface more than actual test points.
>> >>>>
>> >>>> Does you computer recognise the microbit at all?
>> >>>>
>> >>>> On 4 April 2016 at 14:27, Andrew Ferguson 500
>> >>>> <andrewferguson500 at gmail.com> wrote:
>> >>>>>
>> >>>>> Hi,
>> >>>>>
>> >>>>> I managed to persuade my teacher to let me borrow a teacher
>> >>>>> Micro:bit over the Easter holidays (I'm in Scotland so the
>> >>>>> student devices haven't arrived yet), but unfortunately I seem
>> >>>>> to have broken it. (I was just using 'screen' to test serial
>> >>>>> communication, one minute it worked and the next the screen
>> >>>>> session had closed, the micro:bit status light was off and the
>> >>>>> USB chip on the micro:bit got very hot).
>> >>>>>
>> >>>>> I suspect it's probably irreversibly broken, but I noticed that
>> >>>>> on the back of the micro:bit there are several testing points
>> >>>>> that may provide some insight as to what went wrong if probed
>> >>>>> with a multimeter. Does anyone know if there are any docs
>> >>>>> relating to which testing point links to what?
>> >>>>>
>> >>>>> Thanks, Andrew
>> >>>>>
>> >>>>>
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>
>
>
> --
> Giles Booth
> www.suppertime.co.uk/blogmywiki
>
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-- 
Giles Booth
www.suppertime.co.uk/blogmywiki
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