Extending a RISC-V Core with a CAN-FD Communication Unit

The last decade brought up the tendency of turning every tool and device around us into a smart, autonomous, interconnected, and interoperable instrument. Autonomous driving initiative is on the verge of introducing self-driving cars with a high level of safety. Aerospace industry delivers products which improves the flight efficiency and safety, helping the pilots take the best decisions. Astronauts are no longer required to go themselves on the Moon and to risk their lives because smart interconnected robots can perform very complex spatial missions. All of these wouldn't be possible without the continuously development of the Embedded Computing. MCUs (Microcontroller Unit) and SoCs (Systems on a Chip) were permanently improved in terms of working frequency, number of processors and fast peripherals. But we reached a point when improving these parameters is not enough and the necessity of application-specific hardware accelerators and algorithms arose. A field of Embedded development which we think is suitable for integrating an application-specific hardware unit is the CAN-FD communication. This paper describes integration of a CAN-FD Communication Unit into an ISA-extended RISC-V Core (RisCanFd CPU) and designing the MCU which embeds it, called RisCanFd. Our design includes also a debugging unit called UartDebugger which eases the development of programms for RisCanFd. For offering a modern development approach, a GUI application called RisCanFd_DebugIDE was written together with a dedicated assembler, RisCanFd_Assembler. This software tool offers both develop and debug perspectives. RisCanFd may be an alternative to using classical microcontrollers with external or internal memory-mapped CAN-FD (Controller Area Network Flexible Data rate) communication peripherals. Our solution is bringing considerable improvement, which will be presented in this paper.