OpenThread & Bluetooth platform integration in BPI R4 with silabs radio

Scope

Goal is to understand and bringup required platform for supporting thread & Bluetooth in RDK-B Bananapi R4 with silabs module

Banana Pi R4 release used

• Beta engineering release of 05 Feb 2025

Hardware used

•  Silabs xG24 Explorer Kit (brd2703a)

Where to purchase hardware

• https://www.silabs.com/development-tools/wireless/efr32xg24-explorer-kit?tab=overview

Highlevel block diagram of Thread & Bluetooth

• otbr

Kernel side changes for Thread

• Minimal kernel changes

  • CONFIG_USB_ACM=y

    • drivers/usb/class/Makefile

    • Description - ACM support for UART communication

  • CONFIG_TUN=y

    • drivers/net/tap.c

    • Description - TUN generic  support 

  • CONFIG_IEEE802154=y

    • net/ieee802154

    • Description - Generic IEEE802154

  • CONFIG_MAC802154=y

    • net/mac802154

    • Description - Generic MAC layer for IEEE802154

User space code changes for Thread

• cpcd

  • https://gerrit.teamccp.com/plugins/gitiles/rdk/yocto_oe/layers/meta-rdk-comcast-broadband/+/refs/heads/25Q1_sprint/recipes-connectivity/cpcd

• otbr-agent

  • https://gerrit.teamccp.com/#/c/887931/

Yocto changes for Thread

• Image install changes in BPI for thread

  • otbrinstall11

Runtime changes for Thread

• cpcd.conf

  • set disable_encryption to true

• cpcd.service

  • Remove ExecStartPre=/usr/bin/init-iot-radio.sh

• Directory creation

  • mkdir /nvram/icontrol/etc/thread

• otbr-agent.service

  • update debug level to 7 from 5 

Testing of thread

• cpcd service should be up and running
• otbr-agent service should be up and running
• ot-ctl shoule be accessible and get state

  • W:~# ot-ctl 
    > state
    disabled
    Done
    > 

Firmware upgrade of BRD module

• Use simplicity studio
  • Use commander tool 
  • Installed software in ubuntu and connected module with USB Type C
• Get Approval from Thomas Lea to get access to the firmware - rcp-multi-all-4.4.5-2-brd2703a.hex

Documentation for thread

• https://docs.silabs.com/multiprotocol/latest/multiprotocol-solution-linux/
• https://openthread.io/

Key check points when we land in issues for thread

• Make sure we have wpan0 interface up
• brlan0 should be up and running
• wpan0 - who creates it ? - otbr-agent

  • More technical explanation on user space

    • Initial OTBR-agent startup:
      • OTBR-agent process starts
      • At this point, no wpan0 interface exists yet
      • No socket exists yet at /run/openthread-wpan0.sock
    • OTBR-agent creates socket:
      • Creates Unix domain socket at /run/openthread-wpan0.sock
      • This socket will be used for IPC/control operations
    • OTBR-agent creates network interface:
      • Creates the wpan0 network interface
      • Takes ownership of managing this interface
    • Runtime dependencies:
      • The wpan0 interface is ONLY available while OTBR-agent is running
      • If OTBR-agent stops, the wpan0 interface goes away
      • Other services/processes should not expect wpan0 to exist without OTBR-agent running
    • Communication flow:
      • Other processes can communicate with OTBR-agent through the socket at /run/openthread-wpan0.sock
      • Network traffic goes through the wpan0 interface managed by OTBR-agent

  • Can i assume that the above mentioned kernel config to be enabled,if so why , kernel side explanation

    • 1. CONFIG_TUN=y
         • Required since OTBR-agent creates the wpan0 network interface
         • The TUN/TAP driver support enables creation of virtual network interfaces
         • Without this, OTBR-agent wouldn't be able to create the wpan0 interface
      2. CONFIG_IEEE802154=y
         • Required as the base IEEE 802.15.4 protocol support
         • Provides the fundamental IEEE 802.15.4 networking stack
         • OTBR-agent uses this for Thread networking which runs on 802.15.4
      3. CONFIG_MAC802154=y
         • Required for MAC layer operations of IEEE 802.15.4
         • Handles MAC layer functionality like addressing and frame formatting
         • OTBR-agent relies on this for proper 802.15.4 packet handling

      Without these kernel configurations:

      • The wpan0 interface creation would fail
      • The IEEE 802.15.4 networking stack wouldn't be available
      • The MAC layer operations for Thread networking wouldn't work

Code changes to support Bluetooth 

• Prerequisite - Bluetooth support in Banana Pi R4(Reference) - Generic Module
• steps
  • cd meta-cmf-broadband/recipes-connectivity
  • mkdir bt-host-cpc-hci-bridge

  • download recipies

    • get the bb file and service files from - https://github.com/cpokuru/yocto-staging/

  • Install btattach

    • install-btattach

  • Image install

    • imagebthci

Testing bluetooth

• process state

  • psatet

• hciconfig

  • hciconfigefr

• Device connection using bluetoothctl

  • btefrtest
  • Module test - TAPO Matter smart plug

• systemctl status

  • sysbt