MISC-TN-022: Advanced controller for DMX / RDM lighting applications
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History[edit | edit source]
| Version | Date | Notes |
|---|---|---|
| 1.0.0 | May 2022 | First public release |
Introduction[edit | edit source]
This Technical Note (TN for short) illustrates the concept behind a custom product developed by DAVE Embedded Systems for a customer operating in the professional lighting market. This project is a useful use case for showing some interesting technologies that can address common requirements in the world of embedded systems for industrial applications.
Overview[edit | edit source]
The following image depicts the product's block diagram.
As shown, the product features a rich set of I/O's ranging from the DMX/RDM channels to the network interfaces.
The core of the system is the Orca SoM, which in turn is built around the i.MX8M Plus system-on-chip by NXP.
Functionally, the product is dual-role: it can operate either as a controller or a recorder.
Heterogeneous asymmetric multiprocessing[edit | edit source]
From the computational standpoint, there are two domains running two different operating systems. In this regard, the resulting architecture is an example of heterogeneous asymmetric multiprocessing as it is based on different types of cores, namely the ARM Cortex-A53 and the ARM Cortex-M7.
The system architect chose this implementation because it is convenient to satisfy the diversified product's requirements. In particular, the DMX/RDM subsystem must meet real-time requirements in order to be compliant with the DMX/RDM standards. The DMX/RDM subsystem consists of the ARM Cortex-M7 core working in tandem with an FPGA. On the M7 core, a real-time operating system (FreeRTOS) runs. The application executed on top of the RTOS communicates with the Linux domain through RPMsg-Lite, a lightweight implementation of the Remote Processor Messaging (RPMsg) protocol according to NXP documentation. On the other side, the M7 core is connected to an FPGA through an I2S bus. Even though this bus is conceived for digital audio streams, it fits very well for conveying the data to/from the DMX/RDM channels.
The A53-centred domain runs a Yocto Linux distribution. Here the main application is executed dealing with
