Connect to your target - Qualcomm Dragonwing Documentation

Before flashing a kernel or verifying a boot, you need two physical connections to your Qualcomm^® Linux development kit: a USB connection for fastboot and ADB, and a serial console connection for early-boot log capture.

Required hardware

Item	Purpose
USB-C cable	Fastboot flashing and ADB access
USB-to-serial adapter (3.3 V UART)	Serial console for early-boot output
Host machine running Ubuntu 22.04	Confirmed by Prerequisites & host setup

Set up the serial console

The Qualcomm^® Linux development kits expose a debug UART over a USB-to-serial adapter. The serial console is the primary channel for inspecting early-boot messages, kernel panics, and U-Boot/UEFI output before the network stack is available.

Install a terminal emulator

sudo apt install minicom

Connect the USB-to-serial adapter

Plug the adapter into the host and identify the device node:

ls /dev/ttyUSB*
# or, for CP210x/CH340 adapters:
ls /dev/ttyACM*

Add your user to the dialout group if permission is denied:

sudo usermod -aG dialout $USER
newgrp dialout

Open the serial console

Qualcomm Linux development kits use 115200 baud, 8N1, no hardware flow control:

minicom -D /dev/ttyUSB0 -b 115200

To exit minicom, press Ctrl-A then X. To disable hardware flow control, open minicom settings with Ctrl-A O → Serial port setup and set Hardware Flow Control to No.

Alternatively, use picocom:

sudo apt install picocom
picocom -b 115200 /dev/ttyUSB0

For board-specific UART pin assignments and adapter wiring, refer to the hardware documentation for your development kit.

Set up fastboot and ADB

Fastboot is used to flash kernel images; ADB provides shell access after the device has booted.

Install platform tools

sudo apt install android-tools-fastboot android-tools-adb

Enter fastboot mode

After powering on the device, select Volume Down. The serial console shows:

Fastboot mode...

The exact button combination varies by board. Refer to your development kit’s hardware documentation if the above does not work.

Verify fastboot connectivity

fastboot devices

Expected output (the serial number varies by board):

1234567890abcdef  fastboot

If no device appears, check the USB cable, confirm the device is in fastboot mode, and verify USB permissions:

# Add a udev rule if fastboot requires sudo
echo 'SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", MODE="0666", GROUP="plugdev"' \
    | sudo tee /etc/udev/rules.d/51-android.rules
sudo udevadm control --reload-rules && sudo udevadm trigger

Verify ADB connectivity (post-boot)

After the device has fully booted, ADB should enumerate over the same USB cable:

adb devices

Expected output:

List of devices attached
1234567890abcdef  device

Open a shell:

adb shell

Next steps

With serial console and fastboot confirmed, proceed to Install & boot the kernel to flash your build and verify the running kernel.

​Required hardware

​Set up the serial console

​Install a terminal emulator

​Connect the USB-to-serial adapter

​Open the serial console

​Set up fastboot and ADB

​Install platform tools

​Enter fastboot mode

​Verify fastboot connectivity

​Verify ADB connectivity (post-boot)

​Next steps

Required hardware

Set up the serial console

Install a terminal emulator

Connect the USB-to-serial adapter

Open the serial console

Set up fastboot and ADB

Install platform tools

Enter fastboot mode

Verify fastboot connectivity

Verify ADB connectivity (post-boot)

Next steps