How to Connect the BeagleBone Black via Serial over USB

By Rui Santos, Luis Miguel Costa Perestrelo

The serial port is a way to send data between the BeagleBone Black and another device. Establishing a serial communication between your computer and your BeagleBone Black requires a USB-to-TTL Serial cable.

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For most applications, connecting the BeagleBone Black via SSH over USB is the way to go. This connection technique allows you to send data to and from many devices other than PCs, which may be useful if you’re experiencing booting problems or networking issues. You can see what’s happening to your board right after plugging in the power with a serial debugger.

Windows

If you use Windows, you need to download and install a free application called PuTTY. Here’s how to install it:

  1. Open your web browser.

  2. Go to the free PuTTY download.

  3. Click the putty.exe file to download it.

  4. Run the putty.exe file to install the software.

Before you power up your board, you need to make a few connections:

  1. Connect the USB side of the TTL cable to your computer.

  2. Connect the wires to the J1 headers on your BeagleBone Black as shown:

    • Black wire to Pin 1

    • Green wire to Pin 4

    • White wire to Pin 5

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With PuTTY installed, you can establish a serial communication with your BeagleBone Black. Follow these steps:

  1. Open PuTTY.

  2. In the PuTTY Configuration dialog box, select Serial.

  3. Type the name of your BeagleBone Black’s serial port.

    Open Device Manager to see the serial port’s name. Press Windows+R, type devmgmt.msc, and press Enter. The name of your BeagleBone’s serial port is listed below Ports.

  4. Type 115200 in the Speed field.

  5. Click Open.

  6. Power on your BeagleBone Black with a Mini USB cable.

    You see all sorts of information about the booting process.

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  7. When you’re asked to log in, type root and press Enter.

  8. When you’re asked to type a password, press Enter.

    By default, no password is set.

Mac OS X and Linux

In Mac OS X and Linux, you can use the default terminal window to establish a serial communication. With your BeagleBone Black unplugged, follow these steps:

  1. Open a new window, as follows:

    • On a Mac, navigate to /Applications/Utilities and double-click Terminal to open a new Terminal window.

    • In Linux, press Ctrl+Alt+T to open a new terminal window.

  2. Type ls /dev/tty*.

  3. Connect the USB side of the TTL cable to your computer.

  4. Connect the wires to J1 headers on your BeagleBone Black:

    • Black wire to Pin 1

    • Green wire to Pin 4

    • White wire to Pin 5

  5. Type ls /dev/tty*.

    Now you can see a new device connected to your computer — in the figure, ttyUSB0.

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To establish the serial communication, follow these steps:

  1. Type sudo screen /dev/ttyUSB0 115200.

  2. Power on your BeagleBone Black with a Mini USB cable.

    You see all sorts of information about the booting process.

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  3. Enter your computer password, and press Enter or Return.

  4. When you’re asked to log in, type root and press Enter or Return.

  5. When you’re asked to type a password, press Enter or Return.

    By default, no password is set.