MCUs expand use of touch key in healthcare applications

The company’s touch sensor IP, which offers touch key operation on wet and curved touch panels, achieves high noise immunity and sensitivity. Compared to other entry-level 32-bit MCUs, the RX113 group of MCUs is claimed to deliver higher performance, lower power, and more advanced connectivity and DSP capabilities. The devices, which are based on Renesas’ RX CPU core, support LCD control, USB 2.0 and audio.

To remain up to date with expanding embedded systems design requirements, the MCUs support multiple memory configurations and communications peripherals. These configurations and peripherals include up to 512KB of flash memory and 64KB of SRAM, segment LCD control/drive capability up to 288 segments, I2S for audio processing, serial sound interface and SPI protocols, a 12-bit ADC with internal voltage reference, a 12-bit DAC, a temperature sensor and complete DSP processing capability, including hardware-based divide, for efficient near-sensor processing.

Both mutual- and self-capacitance methods for key manipulation detection are supported by the devices. In mutual-capacitance mode, the capacitive touch sensing unit supports up to 36 channels of key input. Compared to previous implementations, the self-capacitance method provides significantly improved noise immunity and sensitivity. The RX113 group of MCUs also support the company’s 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. Allowing for flexible designs, such as those using curved panels, to be implemented, the capacitive touch sensing unit supports acrylic panels over 10mm thick. To enable user interfaces with non-traditional surfaces to be implemented, Renesas has improved the sensitivity by approximately five times.

For all use cases, the devices deliver flexible power management and optimum power consumption. The MCUs achieve a power consumption as low as 0.1mA/MHz (typical) in operating mode, and only 0.44µA in low-power mode (RAM contents retained), which are claimed to enable the industry's highest level of power efficiency. In LCD drive mode (internal step-up and 1/3 bias operation), the devices achieve a power consumption as low as 1.6µA.

Three run modes, three low-power modes and a flexible clock system are offered with the RX113 group of MCUs. The low power fast wakeup capability enables the MCUs to operate at 0.1mA/MHz in Run Mode and 0.44µA in software standby from which it can wake-up in only 4.8µs. The devices integrate a zero wait state flash with erase/write as low as 1.8V, 1KB erase block size and background operation, and offers erase times as low as 10ms per block.

The RX113 group of MCUs are supported by the company’s RX ecosystem, comprising a wide range of third-party tools, RTOS, and middleware. Support for the IAR compiler and IAR Embedded Workbench IDE and for the Micrium RTOS and Spectrum components is available on request.

The RX113 group of MCUs are available now in sample quantities. Package pin counts range from 64 to 100 pins, while on-chip flash memory capacities range from 128 to 512KB. Production quantities of the devices will be available from February 2015.