R9A02G021 is the first microcontroller with Renesas 32-bit RISC-V CPU core design

Renesas R9A02G021 is the first MCU group to use the company’s in-house designed 32-bit RISC-V CPU core with 3.27 CoreMark/MHz, RV32I base plus M/A/C/B extensions, and features such as a stack monitor register, a dynamic branch prediction unit, and a JTAG debug interface.

Renesas has been making RISC-V chips at least since 2022 with the likes of RZ/Five 64-bit microprocessor and R9A06G150 32-bit voice control ASSP. All those were based on Andes RISC-V cores, but since the company has now designed its own 32-bit core, future Renesas 32-bit RISC-V microcontrollers are all likely to feature the in-house core, starting with the R9A02G021 general-purpose MCU group.

Renesas R9A02G021 RISC-V MCU

Renesas R9A02G021 key features and specifications:

  • RISC-V Core
    • Renesas RISC-V instruction-set architecture (RV32I + MACB + Ziscr, Control and Status Register (CSR) instructions + RISC-V Zifencei Instruction-Fetch Fence)
    • Maximum operating frequency –  48 MHz
    • Debug and Trace – RISC-V External Debug Support
    • cJTAG Debug Port
  • Memory & storage
    • 16 KB SRAM (12KB SRAM and 4KB ECC SRAM)
    • 128 KB code flash memory
    • 4 KB data flash
    • 128-bit unique ID
  • I/Os and peripherals
    • Up to 42 pins for general I/O ports; open drain, input pull-up
    • 6-channel Serial Array Unit (SAU)  – 6x simplified SPI, 3x UART, 6x simplified I2C
    • 2x I2C, 2x UART
    • Remote Control Signal Receiver (REMC)
    • Analog
      • 12-bit A/D Converter (ADC12)
      • 2x comparators (CMP)
      • 2x 8-bit D/A converters (DAC8)
      • Temperature Sensor (TSN)
    • Timers
      • Watchdog Timer (WDT)
      • Realtime Clock (RTC)
      • 8-channel Timer Array Unit (TAU)
      • 32-bit Interval Timer (TML32)
  • Clock Sources
    • External clock input (EXTAL)  – 1 to 20 MHz
    • Sub-clock oscillator (SOSC) – 32.768 kHz
    • High-speed on-chip oscillator (HOCO) – 24/32/48 MHz
    • Middle-speed on-chip oscillator (MOCO) – 8 MHz
    • Low-speed on-chip oscillator (LOCO) – 32.768 kHz
    • Clock trim function for HOCO/MOCO/LOCO
    • IWDT-dedicated on-chip oscillator (15 kHz)
    • Clock out support
  • Safety
    • SRAM parity and ECC error check
    • Flash area protection
    • ADC test function
    • Clock Frequency Accuracy Measurement Circuit (CAC)
    • Cyclic Redundancy Check (CRC) calculator
    • Data Operation Circuit (DOC)
    • Independent Watchdog Timer (IWDT)
    • GPIO readback level detection
    • Register write protection
    • Illegal memory access detection
    • True Random Number Generator (TRNG)
  • System and Power Management
    • Operating Voltage – VCC: 1.6 to 5.5V
    • Low power modes
    • Event Link Controller (ELC)
    • Data Transfer Controller (DTC)
    • Key Interrupt Function (KINT)
    • Power-on reset
    • Low Voltage Detection (LVD) with voltage settings
    • Power Consumption: 162µA/MHz (Active power), 0.3µA (SW Standby), 4µs (Standby wakeup)
  • Packages
    • 48-pin HWQFN (7 mm × 7 mm, 0.5 mm pitch)
    • 32-pin HWQFN (5 mm × 5 mm, 0.5 mm pitch)
    • 24-pin HWQFN (4 mm × 4 mm, 0.5 mm pitch)
    • 16-pin WLCSP (1.99 mm × 1.99 mm, 0.4 mm pitch)
  • Temperature Range – -40°C to +125°C
Renesas FPB-R9A02G021 RISC-V MCU Fast Prototyping Board
FPB-R9A02G021 RISC-V MCU Fast Prototyping Board with Arduino headers

Four devices are currently available with different packages from 16-pin WLCSP up to 48-pin HWQFN. Renesas says the new R9A02G021 MCUs are fully supported by the e² Studio Integrated Development Environment (IDE) just like other microcontrollers from the company with a code configurator, an LLVM toolchain, and the fast prototyping board (FPB) pictured above. But third-party tools and debuggers are also supported including IAR Embedded Workbench IDE with the I-jet debug probe and SEGGER Embedded Studio IDE with J-Link debug probes and Flasher production programmers. Documentation includes the FPB user manual, a Getting Started guide, schematics, Bill of Materials (BOM), and Gerber files.

The R9A02G021 group MCUs have no application-specific features like a machine learning accelerator or graphics engine and are designed as general-purpose devices for IoT sensors, consumer electronics, medical devices, small appliances, and industrial systems.  To demonstrate its functionality, Renesas developed a smart pressure cooker reference design as part of its “Winning Combinations”.

Renesas RISC-V pressure cooker
Block diagram for a smart pressure cooker based on R9A02G021 and other Renesas chips

When I first read the news, I thought IP vendors such as Arm or Andes would have a tough time in the future, as large silicon vendors will develop their own RISC-V cores and related IP, while smaller companies may leverage the existing RISC-V open-source core. So within a few years, the majority of microcontrollers could be RISC-V-based, while RISC-V application processors would ramp up later due to the larger software ecosystem that requires more work. My idea was that maybe in five years RISC-V MCUs would dominate, and RISC-V applications processors in 10 years with a company such as Arm likely to suffer unless they can reinvent themselves.

But I may have been overly optimistic with regards to the timing of RISC-V adoption, as Renesas’ press release quotes “The Microcontroller Market Monitor, 2024 Q1 Edition, Yole Intelligence” with their analyst expecting that “RISC-V should approach 10% of the overall MCU market by the end of 2029 with significant growth potential beyond”.

Some of the Renesas R9A02G021 microcontrollers are available now, with for example, the R9A02G0214CNK (24-pin package) going for $1.27 per unit in 4.9K orders. The Fast Prototyping Board can also be purchased now for $17.29. More details may be found on the product page.

Share this:

Support CNX Software! Donate via cryptocurrencies, become a Patron on Patreon, or purchase goods on Amazon or Aliexpress

ROCK Pi 4C Plus
Subscribe
Notify of
guest
The comment form collects your name, email and content to allow us keep track of the comments placed on the website. Please read and accept our website Terms and Privacy Policy to post a comment.
1 Comment
oldest
newest
mark
mark
28 days ago

Companies will adopt RISC-V where there’s good reason to do so : economics, performance/efficiency, availability and geopolitics.

It’s also encouraging to see silicon design companies eager to use the ISA, and companies like ESP promising pin-for-pin replacement silicon, making adoption easy.

Khadas VIM4 SBC