146 lines
4.2 KiB
Markdown
146 lines
4.2 KiB
Markdown
[](https://github.com/derdoktor667/DShotRMT/actions/workflows/esp32.yml)
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# DShotRMT - ESP32 Library (Rewrite for ESP-IDF 5)
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A modern, robust C++ library for generating DShot signals on the ESP32 using the new ESP-IDF 5 RMT encoder API (`rmt_tx.h` / `rmt_rx.h`).
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Supports all standard DShot modes (150, 300, 600) and features continuous frame transmission with configurable pause.
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**Now with BiDirectional DShot support!**
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> The legacy version (using the old `rmt.h` API) is still available in the `oldAPI` branch.
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---
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## 🚀 Features
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- **All DShot Modes:** DSHOT150, DSHOT300 (default), DSHOT600
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- **BiDirectional DShot:** Experimental support for telemetry and RPM feedback
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- **Continuous Frames:** Hardware-timed, CPU-independent signal generation
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- **Configurable Pause:** Ensures ESCs can reliably detect frame boundaries
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- **Simple API:** Easy integration into your Arduino or ESP-IDF project
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---
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## 📦 Installation
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Clone this repository and add it to your Arduino libraries or ESP-IDF components.
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```sh
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git clone https://github.com/derdoktor667/DShotRMT.git
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```
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---
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## ⚡ Quick Start
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```cpp
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#include <DShotRMT.h>
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constexpr gpio_num_t MOTOR_PIN = GPIO_NUM_17;
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constexpr dshot_mode_t MODE = DSHOT300;
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constexpr bool BIDIRECTIONAL = true;
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DShotRMT motor(MOTOR_PIN, MODE, BIDIRECTIONAL);
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void setup() {
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Serial.begin(115200);
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motor.begin();
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motor.setThrottle(1000); // Set throttle value (48–2047)
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}
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void loop() {
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// Optionally read RPM if bidirectional mode is enabled
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uint32_t rpm = motor.getMotorRPM(14); // 14 magnets
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Serial.println(rpm);
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}
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```
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---
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## 📚 DShot Protocol Overview
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DShot transmits 16-bit packets to brushless ESCs:
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- **11 bits:** Throttle value
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- **1 bit:** Telemetry request
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- **4 bits:** Checksum (CRC)
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Data is sent MSB-first. Pulse timing depends on the selected DShot mode.
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| DSHOT | Bitrate | TH1 | TH0 | Bit Time (µs) | Frame Time (µs) |
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|-------|-------------|-------|--------|---------------|-----------------|
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| 150 | 150 kbit/s | 5.00 | 2.50 | 6.67 | ~106.72 |
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| 300 | 300 kbit/s | 2.50 | 1.25 | 3.33 | ~53.28 |
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| 600 | 600 kbit/s | 1.25 | 0.625 | 1.67 | ~26.72 |
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Each frame is followed by a pause to help ESCs detect separate frames.
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---
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## 🔒 Checksum Calculation
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The checksum is calculated over the first 12 bits (throttle + telemetry):
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```c
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crc = (value ^ (value >> 4) ^ (value >> 8)) & 0x0F;
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```
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### Bidirectional DSHOT
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Bidirectional DSHOT (sometimes called "inverted DSHOT") inverts the signal level:
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A logical '1' is low, and a '0' is high. This signals the ESC to send telemetry packets back.
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**Bidirectional CRC:**
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```c
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crc = (~(value ^ (value >> 4) ^ (value >> 8))) & 0x0F;
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```
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> **Note:** Bidirectional DShot is experimental. Further hardware testing is needed.
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---
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## 🛠️ ESP32 RMT Peripheral
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The RMT (Remote Control) peripheral generates accurate, hardware-timed signals for controlling external devices.
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Perfect for DShot:
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- Hardware-timed pulses
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- CPU-independent
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- Loop mode with inter-frame pause
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- Reliable under system load
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---
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## 📝 API Reference
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- `DShotRMT(gpio_num_t gpio, dshot_mode_t mode, bool isBidirectional, uint8_t pauseDuration = 120)`
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- `void begin()`
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- `void setThrottle(uint16_t throttle)`
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- `uint32_t getERPM()`
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- `uint32_t getMotorRPM(uint8_t magnet_count)`
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See [examples/dshot300/dshot300.ino](examples/dshot300/dshot300.ino) for a full demo.
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---
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## 📖 References
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- [DSHOT – the missing Handbook](https://brushlesswhoop.com/dshot-and-bidirectional-dshot/)
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- [DSHOT in the Dark](https://dmrlawson.co.uk/index.php/2017/12/04/dshot-in-the-dark/)
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- [ESP32 Technical Reference Manual](https://www.espressif.com/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf)
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---
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## 📄 License
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MIT License – see [LICENSE](LICENSE)
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---
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## 👤 Author
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**Wastl Kraus**
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GitHub: [@derdoktor667](https://github.com/derdoktor667)
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Website: [wir-sind-die-matrix.de](https://wir-sind-die-matrix.de)
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