STM32MP1 OpenThread border router

1 Introduction

The OpenThread Border Router (OTBR) is crucial in Matter to enable the communication between IP-based networks. It acts as a bridge between the Thread network and the outside world.
A Thread Border Router supports at least the following functions:

  • Bidirectional IP connectivity between Thread and Wi-Fi/Ethernet networks.
  • Bidirectional service discovery via mDNS (on a Wi-Fi/Ethernet link).
  • Thread-over-infrastructure that merges Thread partitions over IP-based links.
  • External Thread commissioning (for example, a mobile phone) to authenticate and join a Thread device to a Thread network.

2 STM32MP1 OpenThread border router

The STM32MP1 OTBR works with the NUCLEO-WB55RG radio coprocessor (RCP), which is connected to the STM32MP157F-DK2 Discovery kit (wiki for STM32MP15 Discovery kits) or STM32MP135F-DK Discovery kit (wiki for STM32MP13 Discovery kits) through a serial connection using an FTDI.

OpenThread Border Router
Connectivity Matter MP1.png

2.1 Required boards

2.2 STM32MP157F-DK2 and STM32MP135F-DK installation

A Linux® PC running under Ubuntu® 18.04 or 20.04 is required. The developer can follow this link.
The Linux package can be found on Github.

3 NUCLEO-WB55RG RCP installation

  • Step 1: Get the X-CUBE-MATTER from
  • Step 2: Discover the NUCLEO-WB55RG hardware by following this link.
  • Step 3: Install the firmware by following this link.

4 NUCLEO-WB55RG RCP hardware connection

The communication is done through a serial connection. For RCP implementation, UART Rx/Tx are routed to the CN10 pin 35 (Tx) and the pin 37 (Rx) of an external connector. If the platform host uses USB, a USB/UART converter (e.g. FTDI) is needed. In this case, connect its Rx connector (usually the yellow one) to the CN10 pin 35, and its Tx connector (usually the orange one) to the CN10 pin 37. Black connector (i.e. ground) can be found on the CN10 pin 32.

STM32WB RCP hardware connection
Connectivity STM32WB RCP hardware connection.png
Connectivity STM32WB RCP connection.png