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Fried Cobra?


#1

If I shoot 12V down an input by mistake, my cobra shuts down and doesnt come back. Did I fry it? Its either that or I drew too amperage much from a digital pin. The mosfets are very hot. Any ideas?


#2

The pins are 5V tolerant. Not 12V.

If it still works, then it’s probably ok. See if you can read from those pins. (EDIT: With something less than 5V!!)


#3

It’s dead. Won’t even power up. Would drawing to much current from a pin do this?


#4

If I’m understanding the question right, you didn’t draw current from the Cobra at all. You pushed 12V down a pin. Is this correct?


#5

Yeah. 12volts down. I was curious about the over current question. Is there a best practice for protecting the cobra besides being careful? Like opamps or anything?


#6

If you are experienced at SMT, you can buy the EMX module and replace it on your board


#7

I saw that. What about my previous best practice questions?


#8

You could protect the input by using zener diodes and resistors, but that would add lots of cost and board real estate.

Protecting against incorrect voltages, don’t forget wrong polarity.

The bottom line best practice is "don’t connect incorrect voltages?. :slight_smile:


#9

I think what I did was shoot down 12v on the 5v line. i have some 5V and 3.3V regulators im going to wire in tonight to see if that works. Im hoping I just blew them out.


#10

putting 12v into the 5v regulator would not quickly blow it out. It would take some time for the regulator to overheat. I don’t know if the regulator has thermal shutdown. Perhaps it unsoldered itself from the heat.


#11

The 3.3v regulator was fried. I replaced it. the board boots but doesnt have firmware on it. I am able to get into the com port and erase the memory but it stops at 53.2% on the upload of the tinyboot loader. The EMX chip is pretty hot too. SO Im assuming I did blow up enough to make this cobra useless. Live and learn ::slight_smile:


#12

ouch sorry dude


#13

Wow, sorry to hear that. This is why I triple check any and all connections I ever make, Yes it takes more time, but t has saved me many time and much money.


#14

Sorry to hear. I hope it’s just a small part. You might want to contact TinyCLR on this via email.
I also double and if possible triple check my connections before I connect anything. Wise lesson :frowning:


#15

Sounds like EMX module needs to be replaced. Time to learn SMT soldering :slight_smile: