RCSwitchRmt

RCSwitchRmt is an ESP32-focused, multitasking RF OOK library built on top of the RMT peripheral.
It is inspired by the classic rc-switch project but redesigned for modern ESP32 devices, offering a fully non-blocking and hardware-driven architecture for RF communication.

RCSwitchRmt is an advanced ESP32 library that leverages the RMT peripheral integrated in most ESP32 microcontrollers to handle precise, hardware-timed 433/315 MHz OOK (On-Off Keying) communication asynchronously and without blocking the main thread. Inspired by the classic RCSwitch project, it provides full multitasking transmit (TX) and receive (RX) support for ASK-type RF modules such as WL102, RX470, RX500, RX18210, RX531, WL101, FS1000A, MX-RM-5V, T1L, R1L, R1A, T3MAX, R1A-M3, R1A-M5N, STX882, SRX882, STX883Pro, SRX883Pro, T2L_433, H34P, T3-433, H3V4F, H3V3E, E160-T4MS1, E160-R4MS1, TYJM01, RXB8, SYN480R, RFM119, RFM119S, SF R315A, R433A, R433D, 34N01, STX885, among others. It is compatible with a wide range of common protocols used in remote controls and wireless switches, including PT2262, PT2260, EV1527, SC5211, HS2240, HT6P20B, HT12E, RS-200, and more. By combining the precision of RMT with FreeRTOS multitasking, RCSwitchRmt achieves high reliability, non-blocking performance, and full compatibility with standard OOK/ASK wireless communication systems.

⚠️ Note: This library is designed exclusively for ESP32 family boards with the RMT peripheral (ESP-IDF v5+ or Arduino-ESP32 ≥ 3.x).
It will not work on AVR, ESP8266, or any MCU without RMT support.

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Why RCSwitchRmt?

• Non-blocking TX/RX: Uses FreeRTOS tasks and the ESP32’s RMT peripheral for true asynchronous operation — your main loop and other services remain fully responsive.
• Hardware-level precision: The RMT peripheral handles digital pulse generation and decoding in hardware, ideal for OOK, Manchester, or any pulse-width-based signaling.
• Independent TX/RX protocols: Transmit and receive can use completely different protocol definitions.
• Custom protocol builder: Define your own RF protocol with 2 or 4 timing segments (HLHLHLHL) per symbol for flexible encoding design.
• Configurable protocol behavior: Both TX and RX can have their protocol, tolerance, separation limit, and expected bit length adjusted independently.
• Automatic protocol recognition: RX can automatically identify the most probable protocol (like rc-switch), though reception is faster and more stable when the protocol is defined explicitly.
• Multitasking design: Dedicated FreeRTOS tasks manage transmission and reception while RMT performs precise timing at hardware level.
• Protocol compatibility: Fully supports all rc-switch protocols — works with the same common 433 / 315 MHz OOK remote outlets and transmitters.
• Efficient, reliable, and flexible: Hardware-timed, non-blocking, multitask operation maximizes throughput while minimizing CPU usage.

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Features

• Transmit (TX) and receive (RX) 433 / 315 MHz OOK signals using the ESP32 RMT peripheral.
• Asynchronous, multitask design (no need to call repeater() manually).
• Independent configuration for TX and RX protocols.
• Custom user-defined protocols with 2 or 4 timing segments (HLHLHLHL).
• Send behavior configurable by:
  • Repetition count (setRepeatTransmit(n)): number of frames per send() call.
  • Minimum transmit time (setMinTransmitTime(ms)): continuous transmission window.
  • Priority is given to repetition count (n > 1) over time-based mode.
  • Setting milliseconds = 0 disables time-based sending (single burst only).
• RX: auto or manual protocol selection, tolerance and separation tuning.
• Debug logging available through RMT_OOK_DEBUG.
• Compatible with rc-switch device protocols: SC5262 / SC5272, HX2262 / HX2272, PT2262 / PT2272, EV1527 / RT1527 / FP1527 / HS1527, Intertechno outlets HT6P20X
• Dual RX modes:
  • Instant mode — access the latest received frame directly.
  • Buffered mode — stores the last 32 frames (default), configurable buffer depth, ideal for processing after heavy Wi-Fi, ESP-NOW, or MQTT operations.
    The buffer can be read sequentially using: bool read(Decoded* out);

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How send() works

The send(code, bitlen) function automatically adapts its behavior based on your configuration:

• If you call setRepeatTransmit(n) with n > 1, each send() call transmits n frames (burst-count mode).
• If you call setMinTransmitTime(ms) with ms > 0, send() keeps transmitting continuously during that time window (time-based mode).
• If both are set, repetition count has priority — time-based mode is ignored.
• Setting ms = 0 disables time-based transmission completely (default).
• Setting n = 1 returns send() to single-burst behavior.

This dual behavior makes send() flexible and suitable for different use cases — from rapid control bursts to timed continuous transmission.

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Requirements

• Any ESP32 variant with RMT peripheral (ESP32, S2, S3, C3, C6, etc.).
• ESP-IDF ≥ 5.0 or Arduino-ESP32 ≥ 3.0 (core based on IDF 5).
• PlatformIO target: espressif32.

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Installation

Arduino IDE

1. Download or clone this repository into your Documents/Arduino/libraries/ folder.
2. Restart the Arduino IDE.
3. Once published, it can be installed directly via the Arduino Library Manager.

PlatformIO

Add to your project’s platformio.ini:

lib_deps = 
  https://github.com/Upartech/RCSwitchRmt.git