Arduino Uno R3 is an unknown device

Development Tools IDE 1.x
1

Hey there,

I really hope you can help me out. I used my arduino uno to play around but lately tried to use it to controll some leds. So I did build some stuff with another power source and transistors. I sadly did not get it right on the first try so I had to change several things.
When I wanted to change the sketch on the arduino afterwards to try it out it suddenly did not respond anymore. Now its only an unknown device (unknown hardware ID and everything, cant even find it in the hardware manager, only in printer & co menu) which I cant uploade any sketches too. It used to work perfectly before that and the LEDs (green "On" and orange "L") are still on (not blinking though).

I did read that the "L" Led should be blinking after you pressed the reset button. It doesnt :frowning: Is that true? How long do you have to press it?

I really hope you can help me and sorry for my bad english :wink:

PS I did search for this problem but nothing did help (until now)
PPS Using Win 7 x64 here

2

Hi, you´re not the LAST Samurai. Try the following:
Disconnect EVERYTHING from your UNO r3?
Connect it to your PC USB port; You should hear some indication
that Windows detected some hardware and the power LED should turn ON.
If You get a message NEW HARDWARE, reinstall the drivers.
If You had uploaded some sketch the yellow LED might not BLINK,
so don´t worry YET. I use XP; maybe Win7 is a bit different but check
in DEVICE MANAGER your PORTS. You should see “ Arduino UNO R3 ( COMX ) “.
X is the number of the port assigned to your UNO, normally 3.
Open IDE, or any sketch, click on TOOLS, check “ BOARD “ as UNO and “ PORT “ as X.
Try uploading BLINK and come back. Ah, the shortest pulse on RESET is long enough.