Despite its diminutive proportions, the thrust to weight ratio of the DJI Mini 2 is high enough that it can carry a considerable amount of baggage. So it’s no surprise that there’s a cottage industry of remotely controlled payload releases that can be bolted onto the bottom of this popular quadcopter. But [tterev3] wanted something that would integrate better with DJI’s software instead of relying on a separate transmitter.
As explained in the video below, his solution was to tap into the signals that control the RGB LED on the front of the drone. Since the user can change the color of the LED at any time with the official DJI smartphone application, decoding this signal to determine which color had been selected is like adding several new channels to the transmitter. In this case [tterev3] just needed to decode a single color to use as a “drop” signal, but it’s not hard to imagine how this concept could be expanded to trigger several different actions with a few more lines of code.
[tterev3] wrote some software to decode the 48 bits of data being sent to the LED with a PIC18F26K40 microcontroller, which in turn uses an L9110H H-Bridge to control a tiny gear motor. To get feedback, he’s using a small magnet glued to the release arm and a Hall-effect sensor.
Concerned about how much power he could realistically pull from a connection that was intended for an LED, he gave the release its own battery that is slowly charged while the drone is running. You could argue that since the motor only needs to fire up once to drop the payload, [tterev3] probably could have gotten away with not recharging it at all during the flight. But as with the ability to decode additional color signals, the techniques being demonstrated here hold a lot of promise for future development.
Folks have been strapping additional hardware to commercial quadcopters for years, but modifications like this one that actually let the craft release its payload and fly away hold particular promise for environmental monitoring and building mesh communication networks.
nice.
awesome hack. i’m using my mavic for fishing and dropping my bait loads
David … what’s your line dropping setup? … how far out do you drop the bait?
How far out is determined by where the fish are. Gannet makes a good release. Just keep your bait 5′ below the drone to avoid a pendulum effect.
Or tape a photodiode to the LED bar for encoding the colors.
Pro: Warranty not void.
Yep, Adafruit did that with the Mavic Pro
https://learn.adafruit.com/drone-claw
Con: insert two analog conversions in the communication chain. I see the benefit to the warranty, but I’d be much more comfortable with tterev3’s solution.
Very slick.
Smugglers rejoice.
“decoding this signal to determine which color had been selected is like adding several new channels to the transmitter.”
Red: Drop Bomb
Green: Launch Missile
Blue: Fire Gun/Laser
White: All of the above
Very funny 😅
Awesome HACK. Great work. Simple and effective.
Definitely doing this on my mini 2. Awesome.
One question: Considering the mini2 is only 1g under the FAA weight limit, does adding this require you to register it?
The stock Mini2 is actually a bit less than 249 – they are usually around 238g. With this payload dropper at 10g it’s still just under the limit.
Legally you are not allowed to drop anything from any drone in the new regulations in th uk.
Is there a schematic available?
great ,,, you can make me on my mini 2 ????
I can buy a drup with a controller and give it the sigal on, off via the led instead of using the controller.