Feature: Processors and MCUs


For applications where speed is not


a concern, a simple, lower-speed IR interface may be sufficient. Renesas has developed a new IR interface on its RA4C1 microcontroller family. Tis is an 80MHz, low-power, Arm Cortex-M33- based microcontroller that operates at 1.6V. Te device is specifically designed for low-power applications, supporting a wide range of operating modes and peripherals like timers, UARTs and on- chip segment LCD controllers. Te RA4C1 has a new peripheral


function, known as the SCI/AGT gate function (Figure 2). It provides a simple method of modulating a carrier signal generated by an on-chip timer, with data generated from the UART (Figure 3), and directly outputting it to the IR LED I/O pin. Tis way developers can easily generate the signal required to efficiently drive an infrared diode without external components and without requiring many I/O pins. Developers can also choose to use the


output of the IrDA circuit on the RA4C1 to modulate the carrier. Te modulated signal can be output directly or with phase inversion; see Figure 4. Tis simple circuit makes it much


easier for users to generate the signals required to send information across an infrared interface, reducing the additional components required on the PCB and the number of pins on the MCU.


Industry standard Using an industry standard IrDA interface has many advantages: it’s interoperable and can easily be used with many devices. However, it can also be expensive, since it requires external IrDA-compliant IR transceivers. It is not always the lowest power solution either, and can burden the host microcontroller with additional protocol stacks and the control of the external transceiver. Te RA4C1 with its SCI/AGT gate


function provides a much simpler, lower-power set-up. It can be used if a proprietary MCU-to-MCU system is required, where power consumption and cost are important, and there’s no need for interoperability.


Figure 3: SCI/AGT UART frame


Figure 2: SCI/AGT mask function


Figure 4: SCI/AGT IrDA frame


www.electronicsworld.co.uk October 2026 27


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