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USB port malfunction

electrostatic usb serial

Best Answer Chris Walker, 15 February 2014 - 09:23 PM

Hi knut.tveitane, We include 3 fairly expensive ESD chips on every Netduino 2 board, to help protect the USB data and power pins...but they do have limits (i.e. they may not protect against all visible sparks of electricity). It sounds like the amount of ESD may have overpowered the ESD chips (or the spark jumped right over the shell and onto other chips). No fun at all. It sounds like, other than the ESD-shocked parts/pins on the board, the rest of the board is still working...so here are a few options. If you were to recompile the firmware to use UART1 as its default debug port--and then flash that to the board via MiniJTAG--you could likely use the board via USB-TTL cable to pins D0/D1. That's not a super-simple thing to do quite yet (although some community members are working on it). You could also try replacing parts on the board if you have some keen soldering skills and a few diagnostics tools. Chris P.S. We electrically-isolated the USB shells on Netduino 2 Rev A boards; I'll ask our engineers to take a look at adding a separate chassis ground (separated by RC circuit) to a potential Rev B board in the future. That could potentially add some extra ESD protection against visible shocks (which should be rare...but we like to overengineer things). Go to the full post


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#1 knut.tveitane

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Posted 15 February 2014 - 07:46 PM

I was just about to connect the USB cable to my NetDuino plus 2 to download a new experiment, when I noticed a small spark... an electrostatic discharge. The discharge happened between the outer metal shells on the plug and socket - which I believe is unconnected on the Netduino side. Nevertheless, something broke. Result: My computer does no longer recognise the Netduino as an USB device.

 

Except from the malfunctioning USB port, the board seems to work - the last program I dowmloaded, stll performs as it did before, the reset button works and the onboard LEDs work as they should. But without the USB port I am not able to reprogram my Netduino. Or... is there any way I could program it via serial communication (through UART1/pins d0/d1)?

 

If not... there is probably no hope for the board?

 



#2 Chris Walker

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Posted 15 February 2014 - 09:23 PM   Best Answer

Hi knut.tveitane, We include 3 fairly expensive ESD chips on every Netduino 2 board, to help protect the USB data and power pins...but they do have limits (i.e. they may not protect against all visible sparks of electricity). It sounds like the amount of ESD may have overpowered the ESD chips (or the spark jumped right over the shell and onto other chips). No fun at all. It sounds like, other than the ESD-shocked parts/pins on the board, the rest of the board is still working...so here are a few options. If you were to recompile the firmware to use UART1 as its default debug port--and then flash that to the board via MiniJTAG--you could likely use the board via USB-TTL cable to pins D0/D1. That's not a super-simple thing to do quite yet (although some community members are working on it). You could also try replacing parts on the board if you have some keen soldering skills and a few diagnostics tools. Chris P.S. We electrically-isolated the USB shells on Netduino 2 Rev A boards; I'll ask our engineers to take a look at adding a separate chassis ground (separated by RC circuit) to a potential Rev B board in the future. That could potentially add some extra ESD protection against visible shocks (which should be rare...but we like to overengineer things).

#3 knut.tveitane

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Posted 16 February 2014 - 06:27 AM

Thanks for your quick reply, Chris!

 

OK, that sounds like a couple of challenging exercises which will be fun to try when I get more proficient - I will definitely save the board for later. For now, I have ordered a new board - and an antistatic mat for my work desk.



#4 Chris Walker

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Posted 16 February 2014 - 08:34 AM

Hi knut.tveitane, The boards have quite a bit of ESD protection in them. I'd mostly avoid dragging your feet on carpet, etc. Most users benefit from integrated ESD protection and never have an issue. [ Knock on wood :) ] Chris

#5 Paul Newton

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Posted 16 February 2014 - 12:51 PM

Hi,

 

There is a chance that the damage is to the PC's USB port, and not the Netduino.

 

Have you tried another device in that USB port (e.g. a mouse) ?

Have you tried connecting the Netduino to the other USB ports on your PC?

 

Paul



#6 knut.tveitane

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Posted 16 February 2014 - 03:33 PM

Yes, I have tried the Netduino other USB ports, even on another computer. So, the problem is definitely on the Netduino side.

-knut







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