The wireless variant of the ConnectCore 91 SOM integrates the Murata LBEE5PL2DL wireless chipset with the following features:

  • Bluetooth 5.3, ANT+, backward-compatible

  • Bluetooth and WLAN coexistence

Digi Embedded Yocto defines the dey-bluetooth feature that builds the bluez5 package for working with the Bluetooth interface. This package installs all the required libraries and tools to use Bluetooth.

Digi Embedded Yocto supports the core specification 5.3 (GAP, L2CAP, RFCOMM, SDP, GATT), including Classic Bluetooth and Bluetooth Smart (Low Energy). The Linux Bluez stack supports additional Bluetooth Classic and Low Energy profiles that are not specifically validated. See the Bluez documentation for details.

If you have a Bluetooth-capable ConnectCore 91 but you don’t need to use Bluetooth, see Disable Bluetooth for instructions on disabling the interface.

Kernel configuration

The Bluetooth interface is managed by the following kernel configuration option:

Kernel driver

The Bluetooth driver is located at:

File Description

drivers/bluetooth/btnxpuart.c

NXP protocol support

Device tree bindings

The NXP controller device tree binding is documented at Documentation/devicetree/bindings/net/bluetooth/nxp,88w8987-bt.yaml A bluetooth node is given as a device tree placeholder for U-Boot to fill in the Bluetooth interface MAC address. This address is then programmed into the device by the Digi Embedded Yocto bluez init script.

Bluetooth interfaces

Disable Bluetooth

Bluetooth is enabled by default via a device tree overlay on the ConnectCore 91 variants that support it. The Digi Embedded Yocto boot script automatically detects if the variant has a Bluetooth chip and adds the Bluetooth overlay to the U-Boot environment overlays variable.

To disable Bluetooth, set the following environment variable in U-Boot:

=> setenv disable_bt 1
=> saveenv

This prevents the boot script from adding the Bluetooth overlay, which results in the system disabling the Bluetooth interface.

To revert this change, remove the variable and the boot script will load the Bluetooth overlay again.