Renesas Packs Capacitive Touch, Segment LCD, and Security Into MCU
This week, Renesas introduced the RA4L1 microcontroller series, a highly integrated solution designed for low-power, sensor-based applications. The new MCUs include capacitive touch, segment LCD, and advanced security features to meet the high demands of IoT sensing applications ranging from metering and smart locks to HMI designs.
The RA4L1 series targets a range of battery-powered applications. Image used courtesy of Renesas
An Ultra-Low-Power MCU for Battery-Powered Devices
The RA4L1 microcontroller series integrates an Arm Cortex-M33 core with TrustZone support, operating at up to 80 MHz. It features up to 512 KB of Flash memory, 64 KB of SRAM, and 8 KB of data Flash rated for 100,000 program/erase cycles. To support the memory hierarchy, the system has a built-in memory protection unit that defines eight secure and non-secure memory regions.
For connectivity, the MCU family supports a range of communication interfaces, including six serial communication interfaces for UART, SPI, I2C, I3C, LIN, and Manchester encoding. A USB 2.0 full-speed module, a CAN FD controller, and a quad-SPI interface provide additional connectivity for high-speed data transfer and external Flash expansion.
Block diagram of the RA4L1. Image used courtesy of Renesas
The microcontroller’s analog subsystem features a 12-bit ADC with up to 16 input channels, a 12-bit DAC, and dual low-power analog comparators. An integrated temperature sensor enables real-time thermal monitoring, while the timing system includes two 32-bit general-purpose timers, four 16-bit PWM timers, and two low-power asynchronous timers.
Security features include Renesas' Secure IP (RSIP-E11A) for AES and ECC encryption, SHA-256 hashing, and device authentication via a 128-bit unique ID. TrustZone memory segmentation protects Flash and SRAM, while lifecycle management and tamper detection enhance system integrity.
Finally, the power management system supports multiple low-power modes that can reduce standby current to as low as 1.65 µA. The microcontroller nominally operates between 1.6 V and 3.6 V and includes a real-time clock with calendar functionality. Other notable features include an integrated capacitive touch sensing unit, an LCD segment controller, multiple clock sources, and PLL-based frequency scaling.
Integrating UI Features Into the MCU
Capacitive touch sensing and segment LCD integration are both central to the usability and efficiency of modern embedded systems. Devices such as smart meters and home automation panels, for example, often demand intuitive user interfaces with low power consumption.
Capacitive touch sensing operates through changes in electrostatic fields to enable a durable, responsive, and maintenance-free input method without mechanical wear, unlike physical buttons or resistive touchscreens. Segment LCDs provide a display solution that, unlike graphical LCDs or OLED displays, operates much more efficiently. This is because they use static or multiplexed drive schemes that only activate predefined segments without requiring continuous pixel refresh or backlighting.
A segment LCD display. Image used courtesy of Focus LCDs
The combination of capacitive touch and segment LCD technology is particularly relevant in applications that demand both low-power operation and a reliable user interface. In medical devices such as portable glucose monitors, a capacitive touch interface allows easy cleaning and contamination-free operation, while a segment LCD provides a clear, always-on display without excessive power draw. By integrating both features natively, the RA4L1 microcontroller is built to reduce design complexity, minimize external component costs, and optimize power efficiency in these kinds of applications.
Availability and Support Tools
The RA4L1 microcontroller series is now available in multiple package options, including a 3.64 mm x 4.28 mm wafer-level chip-scale package (WLCSP) to accommodate size-constrained applications, such as portable printers, digital cameras, and smart labels. Renesas provides an RA4L1 evaluation board and the RA4L1 Capacitive Touch Renesas Solution Starter Kit (RSSK) to help designers implement the new series into their own designs.
