Air Bit Drone - Technical Information

Support micro:bit
1

Have always been interested in drones, but didn’t want to just buy a retail one that just fly’s with no modification ability. So the one below looked interesting using micro:Bits and I bought one.

My first impression when I opened the package was; is this all I get for $259. IMHO I think this product is overpriced. It comes with no instructions, just a piece of paper pointing to the web site. The web site has the bare basics to get it to fly, literally no technical information. Yes I probably should have researched it more, maybe I could have just started from scratch maybe there are better products out there. Anyway …

It fly’s if you load the code from the web site, but not very well. It seems to have no inbuilt hover or stability. It simply moves as the controller moves; it is very easy to get out of control as a slight movement of the controller moves the drone significantly. And you tend to overcorrect.

So I started to investigating the code. Pitch, Roll, Yaw & Throttle are sent from the micro:Bit to the control board via a serial string. I changed the controller to send just Throttle, no other movement commands. It lifts off and drifts in one direction quite fast indicating the control board is simply adjusting the motors related to the commands it receives. So any stability would have to come from the micro:Bit; but the web site code did not have any built in. It looks like they may have been going to as there is a variable called Autopilot, but it does nothing.

I am happy to try to develop stability software. But, I would like more information on the control board, what do all the lights mean, why is one flashing. How is P0 used to detect battery voltage and charge conditions. I have done some research measuring the voltage on P0 and displaying the level calculated by the code, but still not 100% on it. Some form of basic schematic would help.

I know what I am asking should be directed to the manufacturer and I will do that in time.
Would like to hear from others who may have purchased this product and their experience.

Regards
Jim

PS I will keep investigating this product and place what I find here.

PS This is for Core Electronics. The control board antistatic bag had been opened before I received the product. The control board works … like I think it is supposed to … but …

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2

Battery monitoring.
The control board uses P0 of the micro:Bit for a battery monitoring function.

When on battery power the voltage drops from 2.95V fully charged to 2.5V discharged as the drone is used Representing the Lipo change from 4.2V fully charged to 3.7V discharged.
On the drone and controller board, this indication is spread across 5 LEDs. (0.1V per LED)

Upon plugging in a charge source (USB connector) the P0 voltage drops to 1.6V and a blue LED is lit.
The code recognises this and displays a battery charging animation and stops the drone from acting on any commands from the controller.

Once charged the P0 voltage is about 2.46V and the blue LED is off.
The original code then display a skull indicating a dead battery; which would be correct if the battery was at that voltage. Removing the charge cable and turning it on the indications were then correct. I changed the code to display a tick when charging ceased as I thought if more appropriate. (the battery had just been charged and a dead indication was confusing)

I think the function of changing the voltage on P0 to indicate battery status an excellent idea. I just wish the documentation explained it a little better. The values in the program to calculate battery millivolts are not 100% correct as the battery measures 4.19V fully charged but the program says it is 4.32V. The battery factor variable was set to 4.42; changing it to 4.2 resulted in a closer to correct battery value (4.153V).

So I now understand the code better and what it is doing with respect to the battery. Some parts were confusing to begin with.

Now to on to more interesting stuff, drone stability.

Cheers
Jim

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