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Renesas and SiLabs Polish Bluetooth

February 18, 2020

Author: Tom R. Halfhill

Renesas and Silicon Labs are touting new microcontrollers that integrate Bluetooth radios for IoT systems and other wireless devices. In addition to implementing Bluetooth Low Energy (BLE), Bluetooth Long Range, and Bluetooth Mesh, the Renesas RX23W adds USB, a controller-area-network (CAN) interface, infrared communications, and capacitive-touch inputs. It’s an MCU that’s virtually an SoC. By contrast, Silicon Labs’ Wireless Gecko Series-2 EFR32BG22 is less integrated because it targets lower-cost, lower-power applications.

Instead of an Arm Cortex-M CPU, the RX23W employs a Renesas RXv2 core. This 32-bit core is incompatible with the Arm ecosystem but scores a respectable 4.33 EEMBC CoreMarks per megahertz (CM/MHz). Silicon Labs employs the slightly lower-performance Arm Cortex-M33 (4.02CM/MHz), but it’s much more power efficient (27 microamps per megahertz versus 120µA/MHz). In the RX23W, the CPU operates at a maximum clock speed of 54MHz. In one of the three Wireless Gecko BG22 products (the C112), the CPU operates at 38MHz; the C222 and C224 double the clock rate to 77MHz.

Depending on the model, the RX23W includes 384–512KB of flash memory for program code and 64KB of SRAM, plus a separate 8KB flash memory for persistent data storage. Renesas pitches the RX23W for home appliances, medical devices, and health/fitness monitors. In factories or office buildings, Bluetooth Mesh can collect data from multiple sensors. The RX23W began production in 4Q19 and costs less than $4 in volume.

Silicon Labs recommends the BG22 for lower-power devices, such as health/fitness monitors, asset trackers, and Bluetooth Mesh nodes. These MCUs include 352–512KB of flash memory, are scheduled for March production, and will cost as little as $0.52 in volume. They are based on last year’s EFR32 Series-2 BG21 chips.

Subscribers can view the full article in the Microprocessor Report.

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