32-bit MCUs for healthcare home appliances and industry, with capacitive touch

December 02, 2014 // By Graham Prophet
Renesas’ RX113 microcontrollers enable touch key operations on curved or wet panels; this expansion of touch entry in healthcare, building automation and home appliance applications is offered with the RX113 Group of microcontrollers (MCUs).

Part of Renesas' RX100 Series, these MCUs offer a single-chip solution with touch sensor IP and low-power technologies. Renesas’ claims for its touch sensor intellectual property (IP) core include high noise immunity and high sensitivity, offering touch key operation on wet and curved touch panels.

Based on Renesas’ RX CPU core, the RX113 Group of MCUs delivers performance, lowest power, advanced connectivity and digital signal processing (DSP) capability in an entry-level 32-bit MCU. In addition to a capacitive-touch sensing unit and ultra-low power, these full-featured 32-bit MCUs also support LCD control, USB 2.0, and audio. The RX113 devices support multiple memory configurations and communications peripherals to keep pace with expanding embedded systems design requirements, including:

• Up to 512 kB of flash memory and 64 kB of SRAM

• Segment LCD control/drive capability up to 288 segments for support of the latest system displays

• I2S for audio processing, SSI (Serial Sound Interface) and SPI (serial peripheral interface) protocols

• 12-bit ADC with internal voltage reference, a 12-bit DAC and a temperature sensor

• Complete DSP Processing capability, including hardware-based divide, for efficient near-sensor processing

The RX113 MCUs support both mutual- and self-capacitance methods for key manipulation detection. The Capacitive Touch sensing unit supports up to 36 channels of key input (in mutual-capacitance mode). The self-capacitance method provides improved noise immunity and sensitivity compared to previous implementations. The new MCUs also support Renesas Electronics' first mutual-capacitance method, which allows touch key operation even when the user is wearing gloves and is highly resistant to incorrect detection even when there is water on the touch key area itself. The Capacitive Touch sensing unit supports acrylic panels over 10 mm thick, which allows for flexible designs, such as those using curved panels, to be implemented. Renesas has improved the sensitivity by approximately 5 times, enabling user interfaces with non-traditional surfaces (e.g., wet panels or gloves) to be implemented.

The RX Family delivers