Battery-Powered IR Remote Development
A compact, battery-powered infrared remote control built on the STM32L microcontroller and a high-efficiency IR LED. The firmware supports five major IR protocols, RC-5 (Philips), Samsung, NEC (LG), SIRC (Sony), and Kaseikyo (Panasonic), delivering universal compatibility across popular TV brands from a single, long-lasting battery cell.
Category:
EmbeddedIndustry:
Consumer ElectronicsClient:
Consumer Electronics PartnerYear:
2022The Challenge
Conventional IR remotes typically support only one or two proprietary protocols, forcing consumers to manage multiple devices or compromise on compatibility. At the same time, maximizing battery life is non-negotiable for a handheld remote, yet implementing five distinct IR encoding standards with precise carrier frequencies and timing requires significant firmware complexity. The challenge was to deliver full multi-protocol support without sacrificing energy efficiency or response speed.
Our Solution
We selected the STM32L series, specifically chosen for its ultra-low-power peripheral set and stop-mode wake-up capabilities, as the MCU foundation. Protocol-specific carrier frequencies (36–40 kHz) are generated via on-chip timers with PWM output driving the IR LED at optimized duty cycles. Each of the five protocols (RC-5, Samsung, NEC, SIRC, Kaseikyo) is implemented as an independent firmware module with its own frame structure, bit encoding, and timing constants. The MCU enters deep sleep between transmissions and wakes instantly on button press, keeping average current draw in the microamp range. Debounced GPIO interrupt handling ensures responsive, glitch-free input.
Key Features
- Five major IR protocols: RC-5 (Philips), Samsung IR, NEC-based (LG), SIRC (Sony), and Kaseikyo (Panasonic): all implemented in firmware with correct carrier frequencies and bit-level timing.
- Ultra-low-power STM32L architecture: Deep sleep between transmissions with GPIO interrupt wake-up, keeping average supply current in the microamp range for weeks of operation on a single cell.
- Timer-driven carrier generation: On-chip PWM timers produce accurate, protocol-specific carrier signals (36–40 kHz) with optimized duty cycles for maximum IR range and efficiency.
- Debounced input handling: Hardware-level interrupt-driven button scanning eliminates false triggers and ensures precise, single-press command transmission.
- Compact PCB design: Tight component layout and minimal BOM deliver a lightweight, ergonomic form factor suitable for consumer product integration.
Technologies
- STM32L
- IR LED
- PWM timers
- RC-5
- NEC
- SIRC
- Kaseikyo
- C
- Bare-metal
Results
Testing confirmed stable signal transmission across all five protocols, verified with commercial TVs from each supported brand. The result is a universal IR remote achieving weeks of battery life, demonstrating that robust multi-protocol firmware and disciplined low-power design are fully compatible goals on cost-effective microcontroller hardware.
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