RISC-V Unleashes Your Imagination
Since October 2020, Renesas has been officially active in the RISC-V microcontroller space and successfully launched two ASSP products, for motor control and voice-driven HMI systems. Now a general-purpose MCU enhances the RISC-V portfolio. It is the first MCU using a RISC-V core developed internally at Renesas.
The R9A02G021 general-purpose microcontroller features an interesting mix of analog and digital peripherals, as shown in the block diagram below.
The device has a generous program memory of 128KB which supports well in-field updates, thanks to the small erasable block size granularity of 2KB, and the capability to swap the initial 16KB startup section for implementing an updatable user bootloader code. To make the update process even more reliable, a flash shield function preserves areas from accidental erasure and the protection can be made permanent.
For software IP confidentiality, a flash read protection function allows the user to define a memory area to hold program code which can only be fetched for execution but not read out as data. This effectively creates an executable section that is protected from simple copying. Production control can be implemented using the Unique ID (a read-only device unique serial number, programmed at the Renesas factory) and the User ID, a 64-bit user-defined value. The User ID can be programmed by the customer in production inside a hidden memory area and becomes readable only if the application image holds a certain 'unlock key' value in a user-defined memory location. In this way, you can make sure that only legitimate applications will have access to the confidential value, which could be used further as a seed for authenticating external agents, generating data encryption keys, etc. In fact, a true random number generator hardware is embedded to support such simple but effective use cases.
