Power efficiency and digital filtering uprated in Renesas’ RX231 MCUs
The RX231 group of 32-bit microcontrollers (MCUs) addresses applications that require high processing performance in environments with low current supply capacity, such as industrial sensors, healthcare devices, and wearable devices, and building automation devices such as thermostats.
The RXv2 CPU core achieves a performance benchmark score of 4.16 CoreMark/MHz, 35% higher than the RX200 Series with the earlier RXv1 core. Operating speed is 54 MHz, and approximate increases of 2-4x in DSP performance and 6x in FPU (floating point) performance are claimed. The RX231 Group uses 0.8 µA in standby mode, while retaining the contents of both SRAM and CPU registers, and consuming only 120 µA/MHz when the CPU is active with peripherals off. RX231 Group MCUs can recover from standby mode in a minimum of 5 µsec, which makes it possible to reduce current loss during the recovery and allow the application to react quickly to external events. Applications can be executed from flash after this time, and analogue functions, such as the ADC, are available. The RX231 Group also supports an additional low power timer (LPT), which consumes only an additional 0.4 µA and allows the user to program the device to wake up from the low power modes with a very wide range of possible timings, minimising current consumption.
The RX231 Group provides capacitive touch sensor capabilities equipped with Renesas’ second-generation capacitive touch technology. With support for up to 24 touch keys for self-capacitance mode and up to 144 keys for mutual capacitance mode, the RX231 MCUs can support LED, buzzer, and communication functions in more basic touch systems such as blood pressure monitors (typically 9 keys), to systems with more elaborate requirements such as security keypads (19 keys) and ovens (25 keys). This touch key functionality combines high sensitivity with a high level of noise tolerance, allowing use even when the panel is wet or when the operator is wearing gloves.
The MCUs have complete USB 2.0 support, including device/host and OTG operation and full compliance to Battery Charging specification 2.0. The devices also feature several connectivity peripherals, including up to 7 SCI channels, SDHI support, a CAN interface with ISO 11898-1 compliance, and an IrDA interface for wireless connectivity and audio support.
There are hardware-based safety features for UL and IEC60730, including self-diagnostic and disconnect-detection monitoring for the on-chip A/D converter; a clock frequency accuracy measurement circuit; an independent watchdog timer, and a built-in hardware memory test to spot anomalies in the internal RAM. For enhanced security, the RX231 provides AES encryption, a hardware-based Random Number Generator (RNG) and Unique Device ID that can be configured to support advanced cryptology requirements.
The combination of a power-efficient core with powerful DSP/FPU operation capabilities enables the Renesas IIR digital filter to use 10% less power and take about half as long as was the case with earlier products.
Samples of the RX231 Group are available now. Mass production of the RX231 Group is scheduled to begin in September 2015.
Renesas; www.renesas.eu
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