32-bit Renesas MCUs expand high-sensitivity touch key options

November 26, 2015 // By Graham Prophet
Renesas Electronics is adding to its touch-based application options for home appliance, building, and industrial automation, with the RX130 group of MCUs; these 32-bit MCUs offer a more convenient development environment for cost-sensitive applications

The RX130 Group of 32-bit MCUs allows embedded developers to incorporate both user interface (i.e., touch key) and system control capabilities in a single MCU. Developers working with capacitive touch-based applications can use Renesas' second-generation capacitive touch technology, with self- and mutual-capacitance capability, in an ultra-low power, low-cost 32-bit MCU fabric.

The new RX130 Group combines sensitivity and noise tolerance, making it possible to develop touch keys employing a variety of cover materials, including thick acrylic, glass, wood, fabric, or stone, for use in a broad array of new applications. These include control panels for electric appliances used in locations where they are likely to get wet, home equipment employing recessed switches for a more attractive design, and industrial machinery that must be operated with gloves on for safety reasons.

With the addition of the RX130 Group, Renesas' lineup of touch key MCUs comprises 256 product versions in total, with flash memory capacities ranging from 64 kB to 512 kB and number of pins ranging from 48- to 100-pins. Pin compatibility and software compatibility are maintained between the RX231 and RX130, making it possible to reuse existing software resources and providing coverage for devices from mid- to low-end to high end.

Features include:

— Ability to detect up to 64 touch keys for simplified board design; the MCUs can support complex user interface requirements with support for up to 36 touch keys in self-capacitance mode and up to 36 keys through matrix configuration. The RX130 Group also offers mutual capacitance mode, which allows the number of touch keys to be expanded up to 64, among the most supported anywhere. This reduces the wiring complexity when adding a touch panel and helps simplify the board design. The high-speed processing of the 32-bit CPU means that the load on the CPU is less than 10% even during 64-key control. The RX130 Group allow the developer to run very processor intensive applications, while still managing the capacitive touch interface.