The Cortex-M85 Makes Its Debut

Nov. 1, 2023

Renesas’ RA8 family is based on the Arm Cortex-M85 with Helium machine-learning acceleration.

What you’ll learn:

Why the Arm Cortex-M85 is significant..
What the Renesas RA8 family brings to the table.

The Renesas RA8 family of microcontrollers, based on the Arm Cortex-M85 architecture, fills the gap between existing Cortex-M solutions and higher-end Cortex-A application processors (Fig. 1). The Cortex-M85 offers advanced functionality, including integrated artificial-intelligence/machine-learning (AI/ML) hardware acceleration. In the video (above), I talked with Kavita Char, Principal Product Marketing Manager at Renesas, about the company’s latest chip family.

1. Renesas’ RA8 family of microcontrollers based on the Arm Cortex-M85 sits between the lower-end MCUs and higher-end application processors.

The RA8 main feature set is provided by the Arm V8.1-M architecture used in the Cortex-M85 (Fig. 2). The platform can deliver 6.39 CoreMarks/MHz and run at speeds up to 480 MHz. The architecture includes TrustZone support as well as Helium, which supplies the AI/ML acceleration. This combination delivers a significant performance boost to general and AI/ML applications.

2. The RA8 family, based on the Arm V8.1-M architecture, delivers 6.39 CoreMarks/MHz.

The architecture adds 150 scalar and vector instructions to the mix along with new floating-point support. The V8.1-M architecture includes Pointer Authentication and Branch Target Identification (PACBTI) support designed to mitigate software attacks that utilize memory safety violations to cause memory corruption. The chips are equipped to prevent differential power analysis and simple power analysis (DPA/SPA) side channel attacks.

The family also provides PSA Certified Level 2 + Secure Element (SE) plus NIST CAVP and FIPS 140-3 certifications. The chips incorporate hardware root-of-trust and secure boot. A ROM provides first boot stage. The Renesas Security IP (RSIP-E51A) adds cryptographic acceleration.

The MCUs come with up to 2 MB of flash, 128 kB of data flash, 1 MB of SRAM, and 1 kB of standby SRAM. There’s ECC functionality and the Octal SPI interface supports decryption-on-the-fly (DOTF) as well as eXecute-in-place (XIP).

The family provides 12-bit ADC and 12-bit DAC support along with a pair of high-speed comparators and a built-in temperature sensor. There's the usual mix of timers and serial ports along with CAN FD and Ethernet support. A CEU camera interface is included to handle video or image input.

The RA8 family works within a wide power range (1.68 to 3.6 V DC). This is handled by an on-chip DC-DC converter. Numerous sleep modes help preserve battery power in embedded applications.

Helium delivers a significant AI/ML boost, offering more performance with lower power requirements or even higher performance when running at full speed (Fig. 3).

3. The Helium support in the RA8 significantly boosts performance for machine-learning inference models.

Developers can get started with the RA8 family using the EK-RA8M1 evaluation kit (Fig. 4). The development board includes single wire debug (SWD) and JTAG support. There are two SeeedGrove interfaces and two Digilent Pmod ports. An Arduino Uno R3 header is part of the package along with a mikroBUS socket. A SparFun Qwiic connection provides I²C support. A 64-MB octa-flash chip brings additional storage. CAN-FD and Ethernet connections are included as well.