I am finished with the first batch of lessons and am eager for more.
Also, how do you reset the sensor board once you have deployed sketches to it from the Arduino IDE?
This is a great question that I’ll be sure to include in an upcoming lesson. If you want to revert to the default factory behavior of the ESP32 is upload this sketch:
Let me know if you have any problems with that. We will have a couple of new courses coming out next week. Glad to hear you’ve made it through the initial lessons!
Thanks for the quick reply.
I wondered if I could just deploy an “empty” .ino file rather than using the big default.ino one. Kind of like you deploy nothing in a node-RED context to erase the last flow file you deployed there.
I guess there is no harm in deploying the full factory default file instead.
One other question. I noticed there was a flight.ino file in the examples folder. This contains flight commands.
What happens if you deploy this, then move the ESP module to the Tello Talent and power it on. How does the Tello know to execute this? And when does it execute it?
Based on some reading, it might be that the side button on the ESP32 sensor module will put the Tello in command mode and then allow the Tello flight control actions to be executed. One of the lines in the flight.ino example is:
tt_sdk.startUntilControl();
and I believe this will suspend further code execution until the Tello TT is in command mode. Then the commands that follow:
tt_sdk.sendTelloCtrlMsg("takeoff");
tt_sdk.sendTelloCtrlMsg("left 30");
tt_sdk.sendTelloCtrlMsg("right 30");
tt_sdk.sendTelloCtrlMsg("land");
tt_sdk.sendTelloCtrlMsg("takeoff");
tt_sdk.sendTelloCtrlMsg("up 30");
tt_sdk.sendTelloCtrlMsg("down 30");
tt_sdk.sendTelloCtrlMsg("land");
Will cause flight behavior.
But of course I could be mistaken in this supposition.
Your supposition is spot on 
Take a look a this line of code:
It’s listening for a button press and when the press happens the led will flash green and the mission you posted above will execute.
It’s a pretty cool capability to have mission code saved onto the ESP32 and invoke with with a button press!
Thanks for the confirmation Dennis.
Will give this a try, especially now that I know how to reset the expansion kit to its initial setup.
If I have the tello iOS app connected to the Tello, will the expansion module mission still fly? I was wondering if these kinds of embedded autonomous missions can lead to the default camera display while the mission is executed.
Looking forward to learning more from this course for sure. Missions to collect sensor data while the Tello is in flight and then have that data transmitted/saved/exported/published.
Your question led me to all sorts of interesting discoveries over the weekend. Unfortunately I could not get the flight.ino file working with the Tello app, but what’s interesting is that it does work in DroneBlocks. I compiled and uploaded the code to my ESP32 board, then opened DroneBlocks and connected to the RMTT network. Then I pushed the button on the side of the ESP32 and watched the mission carry out from the video feed in DroneBlocks. Screenshot below:
Not very exciting as it’s just a capture of my garage door. But it works! Pretty cool concept to experiment with. Thanks for the question.
BTW we just launched a new lesson regarding how to interface with the RMTT matrix LED from Arduino. I hope it helps and more lessons coming soon.
Thanks Dennis. I will see if I can duplicate the result here with Droneblocks and my Tello. I was reviewing your node-RED lessons again and I wonder if that might provide a camera feed option. You provide node-RED dashboard for monitoring a flight.
I completed the matrix lesson already
Can we take advantage of the dual core of the ESP32? Have tasks running in parallel? Was thinking of one thread for sensor work and one for flight control perhaps.
Going to be brave soon and solder the pin headers onto the Expansion module adaptor board. It’s been awhile since I soldered anything.
Curious. Did you add this command to flight.ino:
tt_sdk.sendTelloCtrlMsg("streamon");
I was wondering if this was necessary. Or even allowed.
I have made progress with the node-RED dashboard video feed display. The ESP32 mission flies and the video appears in the dashboard. I need to figure out the minimal node-RED flow to support the video display.