I've heard that modern quadcopters use a DSHOT protocol. Could you describe what it is?
What's its purpose?
DShot is a protocol that flight controllers use for communicating with ESCs. It stands for 'Digital Shot'. It is a new digital communication protocol developed by Flyduino in collaboration with Betaflight as an alternative to Oneshot and Multishot.
Oneshot and Multishot (and standard PWM) all use analogue signals. The length of an electrical pulse determines the value being sent from the flight controller to the ESC. This can lead to problems with accuracy if there are slight differences between the speeds of the clock signals in the ESC and the flight controller (which is why ESC calibration is required with analogue protocols). Also, these signals have a fixed length range of 1 to 2 milliseconds, which means they can't be sent more often than once every 4 ms or so, or 250 times a second.
Digital signals can also be more resilient in the presence of electrical noise.
The number associated with the protocol indicates how much data is sent per second. There are several speed options available: