An Arduino IDE library for generating DShot signals on ESP32 microcontrollers using the **modern ESP-IDF 5 RMT Encoder API** (`rmt_tx.h` / `rmt_rx.h`). This library specifically leverages the official `rmt_bytes_encoder` API for an efficient, hardware-timed and maintainable implementation. It provides a simple way to control BLHeli ESCs in both Arduino and ESP-IDF projects.
- **Bidirectional DShot Support:** Implemented, but note that official support is limited due to potential instability and external hardware requirements. Use with caution (and pull-up).
The library is architected around a single C++ class, `DShotRMT`. It abstracts the ESP32's RMT (Remote Control) peripheral, which is a hardware timer peripheral capable of generating and receiving precisely timed signals.
1.**Signal Generation (TX):** The library uses an RMT 'bytes_encoder'. This encoder is configured with the specific pulse durations for DShot '0' and '1' bits based on the selected speed (e.g., DSHOT300, DSHOT600). When a user calls `sendThrottle()`, the library constructs a 16-bit DShot frame (11-bit throttle, 1-bit telemetry request, 4-bit CRC) and hands it to the RMT encoder. The RMT hardware then autonomously generates the correct electrical signal on the specified GPIO pin.
2.**Bidirectional Telemetry (RX):** For bidirectional communication, the library configures a second RMT channel in receive mode on the same GPIO. An interrupt service routine (`_on_rx_done`) is registered. When the ESC sends back a telemetry signal, the RMT peripheral captures it and triggers the interrupt. The interrupt code decodes the GCR-encoded signal, validates its CRC, and stores the resulting eRPM value in a thread-safe `atomic` variable. The main application can then poll for this data using the `getTelemetry()` method.
The DShot protocol defines specific timing characteristics for each mode. The following table outlines the bit length, T1H (high time for a '1' bit), T0H (high time for a '0' bit), and frame length for the supported DShot modes:
1. Open the Arduino Library Manager (`Sketch` > `Include Library` > `Manage Libraries...`).
2. Search for "DShotRMT" and click "Install".
3. Alternatively, you can clone this repository or download it as a ZIP file and place it in your Arduino libraries folder (`~/Arduino/libraries/DShotRMT/`).
Here's a basic example of how to use the `DShotRMT` library to control a motor. Note that `DShotRMT.h` now includes all necessary dependencies, so you only need to include this single header. Please use example sketches for more detailes:
- **`web_control`:** A full-featured web application for controlling a motor from a web browser. It creates a WiFi access point and serves a web page with a throttle slider and arming switch.
- **`web_client`:** A variation of the `web_control` example that connects to an existing WiFi network instead of creating its own access point.
-`sendCommand(dshotCommands_e command)`: Sends a DShot command to the ESC. Automatically handles repetitions and delays for specific commands (e.g., `DSHOT_CMD_SAVE_SETTINGS`).
-`sendCommand(dshotCommands_e command, uint16_t repeat_count, uint16_t delay_us)`: Sends a DShot command to the ESC with a specified repeat count and delay. This is a blocking function.
-`sendCommand(uint16_t command_value)`: Sends a DShot command to the ESC by accepting an integer value. It validates the input and then calls `sendCommand(dshotCommands_e command)`.
-`sendCustomCommand(uint16_t command_value, uint16_t repeat_count, uint16_t delay_us)`: Sends a custom DShot command to the ESC. Advanced feature, use with caution.
-`getTelemetry()`: Retrieves telemetry data from the ESC. If bidirectional DShot is enabled, this function will return the last received telemetry data.
This library is built upon the ESP-IDF framework, specifically leveraging its RMT (Remote Control Peripheral) module for precise signal generation. For detailed information on the underlying ESP-IDF components and their usage, please refer to the official ESP-IDF documentation:
