OpenOCD Troubleshooting: Device Not Opened (Linux)

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On startup you see an error message indicating that OpenOCD cannot find the device. If your build of OpenOCD uses the libftdi driver library, the error message reads:

Error: unable to open ftdi device: device not found
Device Not Found error with libftdi

Follow these instructions to diagnose the problem.

Step 1: Make Sure the Device is Connected

Unplug your device, plug it back in, and check the all connections to make sure they are secure. Many devices also have LEDs to indicate that they are receiving power. The Flyswatter2 and Hammer all have red LEDs to indicate that they are powered. If you do not see a red light come on when you plug in the device, it isn't receiving power.

The Flyswatter and Flyswatter2 also have green LEDs to indicate active USB connections. If you do not see a green light on your Flyswatter, then the device does not have an active USB connection.

Step 2: Check your Driver Messages

Open a terminal window (Applications menu > Accessories > Terminal) and type:


You will see a list of messages describing driver activity on your system. Look for a message indicating that Ubuntu has detected your device. If you have installed the D2XX drivers you should see something like the image to the right. (Even if you intend to run an OpenOCD build compiled with libftdi, seeing the D2XX drivers does not indicate that OpenOCD will fail.)

dmesg Shows a Connected FTDI Device

If do not see a message indicating that Ubuntu has detected a USB device with an FT2232 interface, or if the message is followed by another message indicating that the device has been disconnected, then Ubuntu does not currently recognize that the device is plugged in.

dmesg Shows a Disconnected FTDI Device

The dmesg command prints lots and lots of messages, often more than you can search through by hand. You can filter the output for messages related to your USB drivers by piping it to grep, like this:

dmesg | grep -i usb

Step 3: List USB Devices

Use lsusb to get information about your hardware. A guide to using lsusb is provided here. Follow the steps shown on the Lsusb page. If you encounter any problems, your hardware may be faulty or there may be a problem with your drivers.