On Windows systems, "strange" problems are occasionally reported, where Windows will not detect new devices. It does not seem to be unique to Teensy. Creating a new user account sometimes solves the problem. Plugging the cable into different USB ports can also help. Rebooting is always a good idea. The best approach is to try on a Mac or Linux machine, or a different Windows machine.

Windows 7: Unknown Device (Code 43)

Windows "Code 43" is a mystery. Other devices, even Apple iPod, have experienced this problem. The solution seem to be be completely powering down, and if a latop, remove the battery for a few minutes. This same solution has been reported multiple times with success.

This code 43 error is a mystery. It might be related to laptops entering suspend mode? If you have any insight, please contact us!

Windows: Teensy Loader Window Does Not Appear

On Windows, if multiple monitors are used and then only a single monitor is later used (eg, a laptop used at a docking station), the Teensy Loader may attempt to appear on the missing monitor. The Teensy Loader appears in the Windows Task Bar, but not on the screen.

Windows 7: Hold the shift key and right click on the Teensy Loader in the Task Bar.
Windows Vista & XP: Right click on the Teensy Loader in the Task Bar.
Select "Move".
Use your keyboard arrow keys to move the window until it appears.

Additional info from Gilbert Hersschens:

"Since you can't see the missing window, you won't know for sure if it's visible or hidden. But you can see this in the context menu. When the window is shown on the missing display, the menu item "Move" will be active and the item "Restore" will be greyed out. When it's hidden, it will be just the opposite. You can only move a window in its visible state. To hide or unhide a window, you can click on the icon in the taskbar to toggle its state or use the corresponding menu items in the context menu.

Linux: Long Delay Before USB Serial Detected

On some Linux systems, USB Serial is detected very slowly. The kernel detects the device quickly (usually seen with "tail -f /var/log/messages"), but the device files do not appear for a very long time.

Edit "/lib/udev/rules.d/77-nm-probe-modem-capabilities.rules", adding this line:

SUBSYSTEMS=="usb", ATTRS{idVendor}=="16c0", ATTRS{idProduct}=="04[7-9]?", GOTO="nm_modem_probe_end"

Linux: Many Duplicate Device Names with Ubuntu 9.10

On Ubuntu 9.10 (and maybe other systems), when using a serial device type, the kernel assigns a new number each time, /dev/ttyACM0, /dev/ttyACM1, /dev/ttyACM2, etc.

This is caused by the Gnome Modem Manager, which holds the port in (as far as the kerel is concerned) use even after you have reset the Teensy and the port no longer exists. The simplest solution is to uninstall Modem Manager, and restart the network manager or simply reboot.

apt-get remove --purge modemmanager

You could also try deleting /usr/lib/ModemManager/libmm-plugin-generic.so and of course reboot. This might leave Modem Manager able to work with most modems, but not interfere with Teensy.

Modem Manager's troublesome probing and inability to configure exclusions for specific device is a known bug. Hopefully it will be fixed in future releases.

Windows: Teensyuino Installer Unable To Write

Please temporarily disable any anti-virus software. Many "heuristic" anti-virus programs do not like one program writting to another. The Teensyduino installer needs to modify many files inside the Arduino software. "Windows Essential Security" has been reported to cause trouble.