DShotRMT - ESP32 Library (Rewrite for ESP-IDF 5)

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).
Supports all standard DShot modes (150, 300, 600) and features continuous frame transmission with configurable pause.
Now with BiDirectional DShot support!

The legacy version (using the old rmt.h API) is still available in the oldAPI branch.

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🚀 Features

• All DShot Modes: DSHOT150, DSHOT300 (default), DSHOT600
• BiDirectional DShot: Experimental support for telemetry and RPM feedback
• Continuous Frames: Hardware-timed, CPU-independent signal generation
• Configurable Pause: Ensures ESCs can reliably detect frame boundaries
• Simple API: Easy integration into your Arduino or ESP-IDF project

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📦 Installation

Clone this repository and add it to your Arduino libraries or ESP-IDF components.

git clone https://github.com/derdoktor667/DShotRMT.git

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⚡ Quick Start

#include <DShotRMT.h>

constexpr gpio_num_t MOTOR_PIN = GPIO_NUM_17;
constexpr dshot_mode_t MODE = DSHOT300;
constexpr bool BIDIRECTIONAL = true;

DShotRMT motor(MOTOR_PIN, MODE, BIDIRECTIONAL);

void setup() {
    Serial.begin(115200);
    motor.begin();
    motor.setThrottle(1000); // Set throttle value (48–2047)
}

void loop() {
    // Optionally read RPM if bidirectional mode is enabled
    uint32_t rpm = motor.getMotorRPM(14); // 14 magnets
    Serial.println(rpm);
}

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📚 DShot Protocol Overview

DShot transmits 16-bit packets to brushless ESCs:

• 11 bits: Throttle value
• 1 bit: Telemetry request
• 4 bits: Checksum (CRC)

Data is sent MSB-first. Pulse timing depends on the selected DShot mode.

DSHOT	Bitrate	TH1	TH0	Bit Time (µs)	Frame Time (µs)
150	150 kbit/s	5.00	2.50	6.67	~106.72
300	300 kbit/s	2.50	1.25	3.33	~53.28
600	600 kbit/s	1.25	0.625	1.67	~26.72

Each frame is followed by a pause to help ESCs detect separate frames.

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🔒 Checksum Calculation

The checksum is calculated over the first 12 bits (throttle + telemetry):

crc = (value ^ (value >> 4) ^ (value >> 8)) & 0x0F;

Bidirectional DSHOT

Bidirectional DSHOT (sometimes called "inverted DSHOT") inverts the signal level:
A logical '1' is low, and a '0' is high. This signals the ESC to send telemetry packets back.

Bidirectional CRC:

crc = (~(value ^ (value >> 4) ^ (value >> 8))) & 0x0F;

Note: Bidirectional DShot is experimental. Further hardware testing is needed.

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🛠️ ESP32 RMT Peripheral

The RMT (Remote Control) peripheral generates accurate, hardware-timed signals for controlling external devices.
Perfect for DShot:

• Hardware-timed pulses
• CPU-independent
• Loop mode with inter-frame pause
• Reliable under system load

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📝 API Reference

• DShotRMT(gpio_num_t gpio, dshot_mode_t mode, bool isBidirectional, uint8_t pauseDuration = 120)
• void begin()
• void setThrottle(uint16_t throttle)
• uint32_t getERPM()
• uint32_t getMotorRPM(uint8_t magnet_count)

See examples/dshot300/dshot300.ino for a full demo.

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📖 References

• DSHOT – the missing Handbook
• DSHOT in the Dark
• ESP32 Technical Reference Manual

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📄 License

MIT License – see LICENSE

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👤 Author

Wastl Kraus
GitHub: @derdoktor667
Website: wir-sind-die-matrix.de