Japanese electronics company Renesas has introduced a group of microcontrollers (MCUs) targeting home appliances and building automation applications.

The low-power 32bit RX140 series is built around the firm’s RXv2 CPU core, and operates up to 48MHz with a CoreMark score of 204, equivalent to approximately twice the processing performance of the RX130 group.

The MCUs can boost power efficiency by over 30 per cent compared with previous RX130 MCUs, achieving power consumption as low as 56µA/MHz when the CPU is in active mode and as low as 0.25µA in standby mode. This enables the MCUs to realise performance and low power consumption in products such as home appliances, and industrial and building automation.

The MCUs use capacitive touch sensing units, offering an enhanced user experience and user interface.

They fulfil the IEC EN61000-4-3 levels four (radiated) and three (conducted) capacitive touch noise tolerance requirements. This shows they are less susceptible to electromagnetic noise, allowing the MCUs to detect changes in water level by directly measuring changes in capacitance through high-precision sensing. Built-in multi-scan functionality and automated sensing enable users to improve sensitivity through simultaneous measurement using multiple electrodes. This allows for automatic touch detection even in standby mode, making it easier to develop interfaces quickly using touchless operation or proximity sensing.

As part of the RX capacitive touch MCU line, the MCUs help users develop high-end capacitive touch systems for applications in various environments. These include home appliances such as microwave ovens, refrigerators and induction heat cooking stoves, as well as manufacturing equipment, building control panels, and devices that can detect remaining quantities of water or powder on surfaces.

“The RX100 series of ultra-low power MCUs is gaining popularity for the superior scalability it offers as the entry-level model for the RX family,” said Sakae Ito, vice president of the IoT platform business division at Renesas. “With the release of the RX140 MCUs offering improved performance and power efficiency alongside the latest capacitive touch IP, we continue to bring advancements that enable customers to create products that combine enhanced functionality, design and usability.”

The MCUs also feature improved peripheral functions. For example, the number of IO ports has been increased to allow control of more sensors or external components, and Can communication support for real-time operation has been added. A built-in AES encryption accelerator and true random number generator reduce the risks of security threats such as data leakage or manipulation.

Designed for scalability, they maintain pin compatibility with the RX130, enabling users to upgrade while continuing to make use of existing design resources.

Renesas has also introduced a target board for the MCUs, which provides access to all signal pins, for initial evaluation work. The board is equipped with a Pmod connector to allow easy connection of sensor modules.

To simplify evaluation of capacitive touch applications even further, the firm plans to introduce a capacitive touch evaluation system, which will be similar to the already available system for the RX130.

The MCUs can be used with the e² Studio integrated development environment, the Smart Configurator code generation support tool, and the QE for Capacitive Touch capacitive touch support tool to shorten development time, reduce costs and improve software quality.

Renesas has created a complete waterproof shower controller with RX140 MCUs and other analogue and power devices from its portfolio, which can be used to provide user interface functionality with an easy-to-use and stylish design.

The RX140 group of MCUs is available in 32- to 64-pin packages with 64kbyte of flash memory. Mass production for additional configurations and memory sizes over 128kbyte will be available starting in February 2022.