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Support Forum » Do I have a bad Serial-to-USB TTL cable?

February 01, 2011
by nateb
nateb's Avatar

I had been working with my Nerdkit sucessfully, using a potentiometer to control a servo, then accidently fed 14-18 volts directly to the the power rail on my breadboard. Subsequently, I saw no activity from the kit at all. I ordered a new ATMega168 project package and LCD.

After some trial and error, I found that my old LCD is likely fried, but the old ATMega168 appears to be good. The new chip successfully displays the default text on the LCD, but I can't get either my desktop or laptop (WinXP and Win7 respectively) to recognize either chip, despite the old setup working on both computers flawlessly.

I tried removing and reinstalling the driver, and tried multiple ports on both computers. Nothing is seen to pop up in the device manager.

Is it possible my Serial to USB TTL cable was damaged along with the LCD? The USB wasn't plugged into anything when I fed in the high voltage, but I think it was connected to the power rails (red to the power rail, and black to the ground rail), and it was certainly connected to pins 2 and 3 of the ATMega168.

February 01, 2011
by Rick_S
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Yep, could have fried it too.

February 01, 2011
by hevans
(NerdKits Staff)

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Hi Nateb,

It is actually quite likely you damaged the cable if you put 14V across its power leads.

Humberto

February 02, 2011
by nateb
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Thanks for the replies. Looks like I'll have to get a new cable. I wish I ordered one with the other parts. Another $5 shipping :(

February 05, 2011
by nateb
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Thanks Rick and Humberto!

I got my new USB cable today (quick shipping!), and everything is working perfectly. I'm very happy to get going again.

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