OpenThread RCP over Arduino header
Overview
This (virtual) shield can be used to connect a board with an Arduino R3 compatible header to an external OpenThread RCP [1] device. The RCP device would function as the Thread radio, while another board can function as the OpenThread host.
Requirements
An RCP radio device is needed for this shield to work. As an example, the reference from OpenThread using the nRF52840 DK is chosen as a demonstration. Refer to the OpenThread on nRF52840 Example website [2].
Both UART and SPI can be used as the transport, depending on the board connections.
The following was executed on Ubuntu 24.04 to build and flash the RCP firmware:
Preparation
git clone https://github.com/openthread/ot-nrf528xx.git --recurse-submodules
cd ot-nrf528xx
python3 -m venv .venv
source .venv/bin/activate
./script/bootstrap
Building
# Set -DOT_PLATFORM_DEFINES="UART_HWFC_ENABLED=1" to enable flow control
./script/build nrf52840 UART_trans -DOT_PLATFORM_DEFINES="UART_HWFC_ENABLED=0"
./script/build nrf52840 SPI_trans_NCP
Flashing
arm-none-eabi-objcopy -O ihex build/bin/ot-rcp build/bin/ot-rcp.hex
nrfjprog -f nrf52 --chiperase --program build/bin/ot-rcp.hex --reset
Pins Assignments
The RCP firmware comes with default pins assigned, the following table lists both the Arduino header pins and the nRF52840DK pins.
Arduino Header Pin |
Function (host) |
nRF52840 DK Pin |
|---|---|---|
D0 |
UART RX |
P0.06 |
D1 |
UART TX |
P0.08 |
Host specific |
UART CTS |
P0.05 (flow control) |
Host specific |
UART RTS |
P0.07 (flow control) |
Arduino Header Pin |
Function |
nRF52840 DK Pin |
|---|---|---|
D8 |
RSTn |
P0.18/RESET |
D9 |
INTn |
P0.30 |
D10 |
SPI CSn |
P0.29 |
D11 |
SPI MOSI |
P0.04 |
D12 |
SPI MISO |
P0.28 |
D13 |
SPI SCK |
P0.03 |
Programming
Include --shield openthread_rcp_arduino_serial or --shield openthread_rcp_arduino_spi
when you invoke west build for projects utilizing this shield. For example:
# From the root of the zephyr repository
west build -b stm32h573i_dk/stm32h573xx --shield openthread_rcp_arduino_serial samples/net/sockets/echo_client -- -DCONF_FILE="prj.conf overlay-ot-rcp-host-uart.conf"
# From the root of the zephyr repository
west build -b stm32h573i_dk/stm32h573xx --shield openthread_rcp_aduino_spi samples/net/sockets/echo_client -- -DCONF_FILE="prj.conf overlay-ot-rcp-host-uart.conf"