The DSHOT protocol consists of transmitting 16-bit packets to the ESCs: 11-bit throttle value, 1-bit to request telemetry and a 4-bit checksum. There are three major protocol speeds: DSHOT150, DSHOT300 and DSHOT600.
| DSHOT | Bitrate | TH1 | TH0 | Bit Time µs | Frame Time µs |
|---|---|---|---|---|---|
| 150 | 150kbit/s | 5.00 | 2.50 | 6.67 | 106.72 |
| 300 | 300kbit/s | 2.50 | 1.25 | 3.33 | 53.28 |
| 600 | 600kbit/s | 1.25 | 0.625 | 1.67 | 26.72 |
| 1200 | 1200kbit/s | 0.625 | 0.313 | 0.83 | 13.28 |
The checksum is calculated over the throttle value and the telemetry bit, so the “first” 12 bits our value in the following example:
crc = (value ^ (value >> 4) ^ (value >> 8)) & 0x0F;
Bidirectional DSHOT is also known as inverted DSHOT, because the signal level is inverted, so 1 is low and a 0 is high. This is done in order to let the ESC know, that we are operating in bidirectional mode and that it should be sending back eRPM telemetry packages.
The calculation of the checksum is basically the same, just before the last step the values are inverted:
crc = (~(value ^ (value >> 4) ^ (value >> 8))) & 0x0F;
The RMT (Remote Control) is a peripheral designed to generate accurate and stable signals to control external devices such as LEDs, motors, and other peripherals. It is well suited for generating the DShot signals in a high-performance and accurate way on the ESP32 platform.
- Generates accurate signals
- Supports programmable timing
- Configurable number of channels
The DShot RMT Library for ESP32 provides a convenient way of generating DShot signals using the RMT peripheral on the ESP32 platform. The library supports all three major DShot speeds: DSHOT150, DSHOT300, and DSHOT600.