The Tello SDK is based on UDP packets so an ESP32/ESP8266 board with WiFi can easily communicate with the Tello. The Tello only works as an Access Point (AP) so one ESP board is required for each Tello. This project is designed to work with the original Tello so it does not depend on the newer features of the Tello EDU or the RMTT. No testing has been done with the Tello EDU and RMTT due to lack of access to the newer drones. This program may work with newer drones and/or newer versions of the SDK because it acts as a bi-directional pass through.
PC (Win,Mac,Linux) <-USB Serial-> ESP board <-WiFi-> Tello
The ESP board is a bridge between the PC and the Tello drone. It communicates with the Tello using Tello SDK UDP packets. It communicates with the PC over USB serial. For example, if the PC sends "battery?" out the USB serial port, the ESP board forwards "battery?" using a UDP packet to the Tello. When the Tello responds, the ESP board extracts the response then sends it to the PC over USB serial. The program running on the ESP board is named ESPTelloCLI because it presents a bi-directional Command Line Interface (CLI) via USB serial port. For the PC programmer, juggling multiple serial ports is easier than juggling multiple USB WiFi interfaces. ESP boards are cheaper and widely available compared to other boards with WiFi and USB serial.
One ESP board running ESPTelloCLI is required for each Tello. Each ESPTelloCLI board appears as a USB serial COM port.
From a terminal program or from the Arduino Serial monitor send commands to connect to Tello like this. SSID and PSK are case-sensitive so be careful.
connect TELLO-xxxxxx
or
connect TELLO-xxxxxx yyyyyyyy
Check for the Tello connection status by sending connect?
connect?
connect? returns ok if connected and error if not.
At this point, commands sent to ESPTelloCLI are passed on to the Tello via the Tello command UDP port. The SDK response is returned without modification.
After connecting to Tello enable SDK mode send command
command
At this point any SDK command may be sent such as battery?,
takeoff, land, etc.
These are the additional commands implemented by ESPTelloCLI.
connect SSID PASSWORD
connect?
telemetryon
telemetryoff
telemetryon turns on output from the Tello SDK State UDP port. The data is formatted in exactly the same way as specified in the SDK document. telemetryoff turns this feature off.
If Tello Telemetry is on, set the Arduino Serial port to the highest possible baud rate. The maximum baud depends on the USB serial chip and the OS driver for the chip.
If using ESP32-S2 or ESP32-S3, use the hardware USB port because it much faster than any UART port. The baud rate is ignored when using the USB hardware port. Regular ESP32 and ESP8266 do not have hardware USB.
There is no support for forwarding video data from the Tello. This might be too much work for an ESP32. The new ESP32-S3 may work but it has not yet been tried.