Serial Port

Table of Contents

• Necessary cables and adapters
• Connecting via Serial Port
  • Linux
  • Windows

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If the D7 is currently using a development image, you can choose either one of the options for connecting: SSH or serial debug port.

On a release image, only the serial debug port is available for getting a console onto the device.

Necessary cables and adapters

Required:

• USB extension cable.
• USB-to-UART adapter board running at 3V.
• 1/16" hex bit or key for the cap screws.
• SKEDD 6 contact 2 row IDC connector cable.

Steps:

1. Connect your workstation to the USB-to-UART bridge using the USB extension cable.
2. Make sure the USB-to-UART bridge is running at 3V.
3. Follow the picture below to uncover the device's debugging serial port.

Remove the highlighted screws

Remove the cap and put it to the side

Move the foam and battery to the side without disconnecting the battery

Plug in the SKEDD IDC connector

The SKEDD connector only goes in one way.

TX and RX pins on the SKEDD connector

Connecting via Serial Port

The default settings for the serial port on the device are:

Setting	Value
Baud rate	115200
Flow control	None
Databits	8
Parity	None

Note: Remember to logout of the session on the device before disconnecting from the serial console. Not logging out before disconnecting will leave the user shell running.

Linux

You will need to identify the serial port on which the device is mounted. Usually, this will be /dev/ttyUSB0, but if you have multiple USB serial devices attached to your workstation, it may be /dev/ttyUSB1 or higher.

To install Picocom and connect to the serial console on the device:

sudo apt install -y picocom
sudo picocom -b 115200 /dev/ttyUSB0 # Replace this with the port your device is mounted on

Note: Except for the baud rate, the defaults for picocom command are similar to the default settings on the D7. We recommend using the baud rate explicitly in the command for best experience.

Remarks

To exit the picocom session type: "Ctrl-a" followed by "Ctrl-x", without the quotes.

Alternatively, GNU Screen is available as well for most distributions.

sudo apt install -y screen
sudo screen -fn /dev/ttyUSB0 115200 cs8 # Replace /dev/ttyUSB0 with the port your device is mounted on

Remarks

To exit screen type: "Ctrl-a" followed by ":", then "quit", without the quotes.

Windows

For Windows it is recommended to use PuTTY.

To figure out which port the D7 is connected to, you can check in Device Manager.

Device Manager

To connect to the device via serial follow the instructions below.

1. Select the Serial radio button
2. Enter the COM port label found in Windows Device Manager
3. Set baudrate to 115200
4. Click Open

PuTTY