IN Brief:
- The RX74M and RX74N are the first RX microcontrollers built on 22 nm technology and incorporating MRAM.
- Both families combine up to 600 MHz RXv3e processing with tightly coupled memory, while RX74M adds EtherCAT, TSN-capable Ethernet, and CAN FD.
- Hardware isolation and expanded cryptography provide tools for connected industrial designs, subject to product-level implementation and compliance checks.
Renesas Electronics has introduced the RX74M and RX74N, two 32-bit industrial microcontroller families built on a 22 nm process and equipped with embedded magnetoresistive memory. Both use the RXv3e core at speeds up to 600 MHz, while their peripheral configurations address different requirements in factory automation and other industrial equipment.
The new devices follow the RX72M and RX72N families, whose maximum operating frequency is 240 MHz. Renesas says the change in processor generation and manufacturing technology increases the processing resources available for control algorithms, communication stacks, and security operations that must run alongside time-sensitive application software.
Each family combines up to 1 MB of magnetoresistive RAM (MRAM) with 256 KB of zero-wait-state tightly coupled memory and 1.5 MB of SRAM. The tightly coupled memory provides a predictable path for time-critical code, while the SRAM accommodates working data and the MRAM provides non-volatile storage. The balance between these memory regions matters when equipment must service frequent interrupts without allowing other operations to introduce unacceptable execution delays.
Unlike conventional embedded flash memory, MRAM does not require an erase operation before writing. That characteristic can shorten some programming and update operations and simplify the storage of logs or changing configuration values. It does not eliminate the need for software to manage data integrity, wear characteristics, or recovery when power is interrupted during an update.
The two product lines are not interchangeable from a communications perspective. RX74M is aimed at equipment such as programmable logic controllers, AC drives, and industrial robots. It integrates an EtherCAT slave controller, a Gigabit Ethernet switch supporting Time-Sensitive Networking, and CAN FD interfaces. Renesas says this combination enables implementations involving EtherCAT, PROFINET, and EtherNet/IP, including EtherNet/IP Device Level Ring redundancy.
EtherCAT supports tightly timed exchanges between controllers and distributed devices. Time-Sensitive Networking adds mechanisms for scheduling and prioritising selected Ethernet traffic, while CAN FD supports communications with distributed controllers and sensors. Integrating the necessary hardware can reduce the number of external interface devices on a control board, although the intended protocols still require appropriate firmware, network configuration, and interoperability testing.
RX74N is directed at applications including smart meters, power conditioners, building equipment, and heating, ventilation, and air conditioning controls. It shares the processing and memory generation with RX74M, but Renesas does not describe it as incorporating the RX74M’s dedicated EtherCAT slave controller. Hardware selection therefore depends on the exact networking functions required, not merely the processor’s headline clock frequency.
Security functions have also been extended. ProtectZone is incorporated into the RX CPU to separate protected and non-protected regions, while the next generation of Renesas Secure IP adds public-key functions, authenticated encryption, and a wider selection of hashing algorithms. The company positions these capabilities as a foundation for security designs that anticipate the EU Cyber Resilience Act and developments in post-quantum cryptography.
The inclusion of cryptographic hardware does not certify a finished machine or connected product against either requirement. Secure boot, authenticated updates, key management, vulnerability handling, and other lifecycle controls depend on the implementation. Isolation features likewise require the memory map, privilege model, and application software to be configured correctly.
Renesas offers 300 MHz versions alongside the 600 MHz variants and reports that the lower-frequency products consume more than 20% less power. This gives developers a choice when the control workload does not justify the maximum clock speed. The devices operate over a stated 1.62 V to 3.6 V supply range, with a junction-temperature specification from -40°C to 125°C, subject to the applicable part and operating conditions.
Package choices include LFBGA and LFQFP formats with different pin counts. The families also support execute-in-place operation from external Octa Flash with on-the-fly decryption, offering another storage option when a design’s code requirements exceed the internal MRAM capacity. The choice of external memory introduces additional board routing, access timing, and security considerations.
Software development is supported through Renesas’ Flexible Software Package and an ecosystem including IAR, RT-Labs, Codewerk, eForce, and Zephyr RTOS. Evaluation boards are available for the two families, allowing engineers to check peripheral behaviour and software compatibility before preparing production hardware. Renesas says both MCU families are available now; the immediate engineering decision is which performance, memory, package, and network combination is appropriate to the intended controller.
