As technology advances, most everyday devices depend on short-range communication to exchange or gather data. Although wireless technologies such as Wi-Fi and Bluetooth dominate the market, they are not always the ideal option especially for low-power applications where efficiency, simplicity, and cost management are most important. In these instances, infrared (IR) communication is still an efficient option that energizes applications such as smart meters, wearable electronics, medical devices, and remote controls.
But using an infrared link is not always easy. An IR diode cannot just be attached to a microcontroller pin and be efficient. In order to avoid saturating the diode and to provide a robust signal, a low-frequency carrier is often employed, which then must be modulated by the data stream. Historically, this has involved using more modem chips, timers, and mixers increasing cost, complexity, and additional board space to the design.
The Inefficient Signal Generation Challenge
Fundamentally, infrared communication relies on two key signals:
- Carrier Frequency – a square wave that paces the IR diode at a suitable frequency.
- Data Stream – the content of the communication, which must modulate the carrier.
In most implementations, these signals are from various peripherals on a microcontroller and must be merged externally. This adds more components and uses multiple I/O pins, which is not conducive to small, battery-powered devices.
A Smarter Way Forward
Since recent microcontrollers started meeting this challenge, they now provide easier mechanisms for IR signal generation. Instead of needing a separate modem chip, some of these devices combine the timer output (carrier frequency) with the communication output (data) internally. The result is a ready modulation that can directly drive an infrared diode.
An example that offers such capability is RA4C1. Being an 80 MHz device with low-power operating modes down to 1.6 V, it offers an SCI/AGT mask function that combines a UART or IrDA interface output with a timer signal and thus makes it possible to generate the required modulated IR output without any external hardware.
Design Flexibility
The reason this method is efficient is because it is flexible:
- Developers have the option of utilizing a basic UART output that is modulated by a timer-generated carrier.
- Or they can implement an integrated IrDA interface, with provisions for direct modulation or phase-inverted output based on the application requirement.
Both schemes present a clean, stable signal while minimizing the amount of external components and I/O pins needed.
For designers of small electronics like handheld meters, fitness monitors, or household appliances space and power efficiency are key considerations. An IR communication solution with minimal IR circuitry saves cost and enhances reliability by eliminating outside circuitry. It also aids in speeding up product development as engineers no longer need to spend extra time connecting individual modem chips or modulation hardware.
Conclusion:
Infrared communication remains to provide a reliable, low-cost solution for short-range connectivity, particularly in environments where the inclusion of a full radio system is not warranted. With newer microcontrollers embracing built-in modulation capabilities, establishing an IR connection has never been simpler. This change makes it possible for developers to provide smarter, power-sensing products while maintaining simplicity and low cost.
(This article has been adapted and modified from content on Renesas.)
