I was using a windows xp professional SP3, and Arduino Uno R3 with starter kit. When I plugged in USB cable, I could hear the computer's sound for "recognizing" it, just like the sound when a computer recognizes a mouse.
But when I opened device manager--->Ports, I could only see Communications Port(COM1), no Arduino port. I was trying to update the driver on that port, but it didn't work. The "ON" light was on (green), and the "L" light was flashing yellow. Then I open Arduino software, and tried to upload the simple example "blink", this is the message I got:
avrdude: stk500_getsync(): not in sync: resp=0x00
I googled it and found out it means the computer is not communicating with Arduino Uno. I changed another USB cable, but the problem was the same.
Right click the Unknown Device in Device Manager
Select Update Driver Software
Select Browse my computer for software
Click Browse button
Select the Drivers folder under the location of your Arduino software installation. (Do not select the FTDI folder inside the Drivers folder)
Click OK
Click Next
Thanks Louis! My problem is there was no "Unknow Device" in the Ports, there was only COM1 under Device Manager--->Ports. But I did what you suggested with COM1, still didn't work...
i have the same issue,and i followed those stepes and in Device manager arduino is shown in PORTS(COM &LPT),but i stiil get this error avrdude: stk500_getsync(): not in sync: resp=0x00.