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I just lost my FEZ Domino


#1

I dont know what happened as it was only running a small program cycling through colors on an RGB LED, and it just died.
I unplugged the USB and back in again. No response from the Domino and my mouse (attached to the same USB hub acted up strange). Tried to power it externally but it draws 1A at 7,5V so something is totally fried here. :’(

Ill have to order me a new one as this was the one paid for by UiO for Whirligig and I was trying to make something for the Halloween contest. With my current luck it wont arrive until the deadline runs out.
:wall:


#2

Maybe it is the HUB or the PC? Reset the PC then connect Domino itself directly to a port


#3

I have seen this to… it helped to turn off the pc and unpluged the power for a short time and then plug it back in. After that all did work again.


#4

I have tried that. I even hooked it up to another PC, no go.
As I said. If it draws 1A of current with nothing but the board, -there must be something seriously wrong.
:frowning:
I have already ordered a new one. Hopefully they will send it straight away.


#5

Same symptoms as me… Almost 1A without any load and the chip very hot (is yours hot, too ?)

Maybe a bad chip ? Domino’s design can’t be faulty otherwise everyone else would also fry their boards ???


#6

I have noticed if you run the domino and LCD from the 5v direct from the USB there is quite a low voltage present… I think these devices really need at least 4.85v with a decent current supply… I know the domino will be okay on the USB but who knows with an LCD connected the backlight on these take a bit of current…

I always connect to an external supply aswell… Luckily for me my system just froze but things were hot…


#7

Yes Bec a Fuel, It heats up very fast. It’s gone in the junk box for now.

The good thing is that my Panda arrived today so I can still work :slight_smile:


#8

Do you connect the RGB LED directly to a FEZ Domino Pin, or via transistor? FEZ Pins can only drive 4mA.


#9

Yes, how did you connect the stuff? Are you using a external supply?


#10

It was an common cathode RGB so every color was connected to a IO pin and run with PWM. The cathode was connected to a 220R resistor to ground.

I didn’t know about the 4mA limit on the IO pins, as it’s nowhere to be found in the documentation on this site. I think if you took a poll of the people that has bought FEZ and asked them what the current limit are, few would get the answer right.

But on this note. What is the total current limit for all the IO’s combined? (this must be easy for all you guys that has read the datasheet). :wink:


#11

I’m surprised at this… If you had a possible maximum current of 12mA on three pins (I know that sounds like 3 times the allowed current) but if you were feeding them with a pulse width signal it would have been considerably lower and should’nt have died. And even if it did I would have expected one of the colours at least to have failed first…

The datasheet isn’t really clear on current source / sink values the 4mA spec is actually listed as the min value… The short circuit current is listed as 50mA output source and 45mA output sink… I’m afraid that doesn’t give me a definate answer whether this is for seveal pins at a time.

Looks like NXP doesn’t give all the data we need…

Cheers Ian


#12

Anyway I learnt a lesson here. So now I have stocked up on transistors http://cgi.ebay.com/20-PCS-2N3904-TO-92-NPN-switching-transistors-/120628864375?pt=LH_DefaultDomain_0&hash=item1c160a6577
:slight_smile:


#13

few 3904 transistors should be in everyones “drawer of goodies” :smiley:


#14

FEZ Domino accepts up to 16mA and more. please read this:
http://www.tinyclr.com/forum/1/1290/