The IR receiver contains a photodiode sensitive to 940 nm IR and a demodulator tuned to 38 kHz. When a remote button is pressed, the transmitter emits 38 kHz bursts encoding a command via NEC, RC5, or SIRC protocol. The receiver outputs a clean digital pulse train the MCU decodes into device address and command byte.
| Operating voltage | 3.3 – 5V |
| Carrier frequency | 38 kHz |
| Detection range | Up to 18m |
| Output | Active-low digital |
| Protocols | NEC, RC5, SIRC, JVC |
| Reception angle | ±45° |
The internal photodiode generates current proportional to incident IR light. A bandpass filter centred at 38 kHz rejects ambient IR from sunlight and incandescents. The demodulator envelope-detects the carrier and outputs an inverted logic signal — LOW during burst, HIGH during gap — which the MCU decodes by measuring pulse widths.
Cannot distinguish remotes without protocol decoding. Susceptible to fluorescent light interference. Range drops in bright sunlight. Decoding requires precise microsecond timing.