This platform is based on Open IoT SDK. Open IoT SDK is a reference implementation of Open-CMSIS-CDI which defines a common device interface for microcontroller-based devices used in the Internet of Things. It is delivered as a framework of software components with a set of feature-rich example applications.
Open IoT SDK uses CMake as its build system. To integrate with Matter's GN build system our top level CMakeLists.txt generates GN configuration files that pass on the required configs required by the GN build.
Supported targets are the ones supported by the Open IoT SDK. Currently it ships with support for Corstone-300 and Corstone-310. This platform makes no assumption on the target and will support any targets added to Open IoT SDK.
The fast models of supported platforms have two network modes:
user mode networking - emulates a built-in IP router and DHCP server, and routes TCP and UDP traffic between the guest and host. It uses the user mode socket layer of the host to communicate with other hosts. See more details: User mode networking
TAP/TUN networking mode - set fast model to host bridge component which acts as a networking gateway to exchange Ethernet packets with the TAP device on the host, and to forward packets to model. See more details TAP/TUN networking mode
Due the user mode limitations, the TAP/TUN networking mode is preferred for implementing IP communication for a Matter project.
Open IoT SDK uses CMSIS-RTOS2 API as its RTOS API. It offers the choice of implementation between FreeRTOS or CMSIS RTX but this is hidden below the API so your choice has no bearing on this port and indeed your application may provide your own implementation entirely.
The platform currently only offers connectivity through the Ethernet interface. This is limited by current support for network interfaces in Open IoT SDK.
This means that commissioning is simplified since no provisioning is required to provide the device with network credentials.
LWIP is used in the implementation of endpoints as the IP stack. LWIP library is provided through the Open IoT SDK.
Mbed TLS is provided through the Open IoT SDK, the Matter version is not used. Configuration of Mbed TLS is in config/openiotsdk/mbedtls.
Storage in Open IoT SDK is provided by TDBStore which is a simple Key-Value Storage over a block device.
NOTE
On the Corstone targets this currently is implemented as a RAM memory region emulating a Flash device. This does not offer persistence between launches.
Open IoT SDK does not currently offer an RTC. Matter configuration has been set accordingly and real time cannot be read from the system.
Monotonic clocks are available and are based on system tick count. They are limited by the target configuration. The current targets set the tick to 1 ms. This becomes the lower bound for timers.
Drivers are provided by Reference MCU-Driver-HAL driver implementation for Arm platforms which is provided by Open IoT SDK.
Trusted Firmware-M (TF-M) implements the Secure Processing Environment (SPE) for Armv8-M, Armv8.1-M architectures and dual-core platforms. It is the platform security architecture reference implementation aligning with PSA Certified guidelines, enabling chips, Real Time Operating Systems and devices to become PSA Certified. TF-M relies on an isolation boundary between the Non-secure Processing Environment (NSPE) and the Secure Processing Environment (SPE).
TF-M consists of:
Secure Boot to authenticate NSPE and SPE images
TF-M Core for controlling the isolation, communication and execution within SPE and with NSPE
Crypto, Internal Trusted Storage (ITS), Protected Storage (PS), Firmware Update and Attestation secure services