XIAO BLE (Sense)

Overview

The Seeed XIAO BLE (Sense) is a tiny (21 mm x 17.5 mm) Nordic Semiconductor nRF52840 ARM Cortex-M4F development board with onboard LEDs, USB port, QSPI flash, battery charger, and range of I/O broken out into 14 pins.

Hardware

  • Nordic nRF52840 Cortex-M4F processor at 64MHz

  • 2MB QSPI Flash

  • RGB LED

  • USB Type-C Connector, nRF52840 acting as USB device

  • Battery charger BQ25101

  • Reset button

  • Bluetooth antenna

  • LSM6DS3TR-C 6D IMU (3D accelerometer and 3D gyroscope) (XIAO BLE Sense only)

  • PDM microphone (XIAO BLE Sense only)

Supported Features

The xiao_ble board supports the hardware features listed below.

on-chip / on-board
Feature integrated in the SoC / present on the board.
2 / 2
Number of instances that are enabled / disabled.
Click on the label to see the first instance of this feature in the board/SoC DTS files.
vnd,foo
Compatible string for the Devicetree binding matching the feature.
Click on the link to view the binding documentation.

Connections and IOs

The XIAO BLE wiki [1] has detailed information about the board including pinouts [2] and the schematic [3].

LED

  • LED1 (red) = P0.26

  • LED2 (green) = P0.30

  • LED3 (blue) = P0.06

Programming and Debugging

The xiao_ble board supports the runners and associated west commands listed below.

flash debug

The XIAO BLE ships with the Adafruit nRF52 Bootloader [5] which supports flashing using UF2 [6]. Doing so allows easy flashing of new images, but does not support debugging the device. For debugging please use External Debugger.

UF2 Flashing

To enter the bootloader, connect the USB port of the XIAO BLE to your host, and double tap the reset button to the left of the USB connector. A mass storage device named XIAO BLE should appear on the host. Using the command line, or your file manager copy the zephyr/zephyr.uf2 file from your build to the base of the XIAO BLE mass storage device. The XIAO BLE will automatically reset and launch the newly flashed application.

External Debugger

In order to support debugging the device, instead of using the bootloader, you can use an External Debug Probe. To flash and debug Zephyr applications you need to use Seeeduino XIAO Expansion Board [4] or solder an SWD header onto the back side of the board.

For Segger J-Link debug probes, follow the instructions in the J-Link External Debug Probe page to install and configure all the necessary software.

Flashing

Setup and connect a supported debug probe (JLink, instructions at J-Link External Debug Probe or BlackMagic Probe). Then build and flash applications as usual (see Building an Application and Run an Application for more details).

Here is an example for the Hello World application.

First, run your favorite terminal program to listen for output.

$ minicom -D <tty_device> -b 115200

Replace <tty_device> with the port where the board XIAO BLE can be found. For example, under Linux, /dev/ttyACM0.

Then build and flash the application in the usual way. Just add CONFIG_BOOT_DELAY=5000 to the configuration, so that USB CDC ACM is initialized before any text is printed, as below:

# From the root of the zephyr repository
west build -b xiao_ble samples/hello_world -- -DCONFIG_BOOT_DELAY=5000
west flash

Debugging

Refer to the J-Link External Debug Probe page to learn about debugging boards with a Segger IC.

Debugging using a BlackMagic Probe is also supported.

Testing the LEDs in the XIAO BLE (Sense)

There is a sample that allows to test that LEDs on the board are working properly with Zephyr:

# From the root of the zephyr repository
west build -b xiao_ble samples/basic/blinky
west flash

You can build and flash the examples to make sure Zephyr is running correctly on your board. The LED definitions can be found in boards/seeed/xiao_ble/xiao_ble_common.dtsi.

Testing shell over USB in the XIAO BLE (Sense)

There is a sample that allows to test shell interface over USB CDC ACM interface with Zephyr:

# From the root of the zephyr repository
west build -b xiao_ble samples/subsys/shell/shell_module
west flash

References