Just got an Arduino UNO and am trying to set it up on my 10.6 mac. I installed the software and got the blink tutorial loaded up, but when I attach the board to the USB cable the "on" light stays red and the L light blinks red. As I understand the light should be green but the troubleshooting guide provides no info for the UNO in this case. The board does not show up under the serial port section. I tried hitting reset but that did not work. Thanks for any info, wondering if I need to send the board back.
try rebooting your computer and check the connecting ports on both the computer and the uno.
also it my have had its bootloader messed up try doing a loop-back test Arduino Forum
A red LED usually means you bought a clone (eBay?) and not an original Uno.
There aren't any multicolor LEDs on the boards.
Hmm, I ordered it from Amazon and it LOOKS just like a normal UNO board, very strange. I cannot do the loop test because it does not create a serial port on my Mac when connected via USB.
Try to find out what USB converter chip is used on the board. A few days ago we had the case that a 'clone' was using a chip by 'Prolific' - which of course needs a different driver.
You can find the vendor/device IDs of those chips in this post. I suppose mac os has ways to find out these numbers as well.
You can look at System Profilier to see what kind of device is detected when attached. (if using lion you need to "System Report" from system information for the same level of information.)
You can also try posting a clear picture of the board.
That is clearly a clone. The PCB is the wrong color. Silkscreen is the wrong font. Couple of the surface mount ICs are the wrong package. And of course, the characteristic red LEDs instead of orange / green. At least they had the courtesy to remove the "Made in Italy" text. (Also is there text missing in the photo, on the ATmega328? It looks like it was sanded off, which is suspicious on its own.)
It looks like it is using the 8U2 like a genuine Uno. Which means it should showing up as a USB modem in the Networking System Preferences.
If it isn't there, then next step is to go to System Profilier and see what appears under USB when it is attached.
Looks like a REV1 UNO, except that the LED color is wrong and it's missing the "Made in Italy" print. So I guess it is a clone.
Now we still need to know how this board identifies itself in your OS (if at all).
You can also try updating the firmware of the ATmega8u2.
Hey there, thanks everyone for the help, I ended up returning the board since it was not the real thing. Looking into ordering a proper UNO now!
If the decision to buy the cheaper first board was money-driven, let it be said that it is not necessary to buy an UNO at all (unless you really need the ATmega8U2 in there). Older 'Duemilanove' boards with the 328 work as well. Just make sure you don't get something that pretends to be something else.
There are many attractively priced alternatives available (seeedstudio, sparkfun, adafruit, moderndevice...). If you think you're likely to fry part of the board, it may also be wise to get a solution with a separate USB section.
I have the same board and You want to download drivers for CH340g converter, here is the link
you will need to make the board a port in device manager and manually install this driver by following the instruction on the link.