This thread is a little brainstorming thread, and I would like to hear some ideas, requests, …
We would like to assembly controller of position lights. I know, that PX4 supports some external I2C RGB LED. It is used for visualisation of controller state. (Armed/disarmed, ready to arm, low battery, errors, … )
Such position lights are very important for evening tests. At this time it is better, but in winter it was a problem. I’m not able to control our small training autogyro model about half an hour before sunset. At a distance of about 100m, I was visually losing UAV orientation.
This position lights should follow this convention: Aviation_navigation_lights
It also should display the state of the controller, and it should be particularly controlled from the ground (throught mavlink/RC).
Lighting modes
For FW I would suggest this principe of lighting. Position lights will always light with less power. And sometimes (~ every 2s) it will flashes twice in time. It is one possible mode.
Next usage is landing light. This must be possible to control from the ground. And it can be turned off in flight (automatically).
For multicopter, it must be able to show orientation in the air. It can be in concert with ‘Aviation navigation lights’ or something different. I assume that each arm will be equipped with RGB LED.
The multicopter can be equipped with a “search/spotting light” directed down or mounted on some gimbal. The intensity of that light should also be controlled from RC.
Light source
That is a question.
For use with FW/Autogyro/helicopter it should be some monochromatic high power LED, some LED strip or some COB module.
For Multicopter it should be RGB high power LED.
Hardware solution
I would like to avoid another firmware out of FC. All SW should be in PX4. Because it is easier to implement these methods and it offers the easiest maintenance.
Therefore, I2C it looks like sollution of this problem. Use some I2C-PWM converter. Here is list of some pre-selected IOs:
- LT3964
- PCA9635
- TPS92515AHV - PWM LED driver
- tps92518hv - SPI or PWM LED driver
- (list is not final)
This light control unit (this PCB) also should be powered directly from the battery (lipol … 3S - 6S??) . It should be equipted with XT30 connector. Type of output connector is not selected yet.
Interface
Prefered is I2C. Next solution is CAN. It also provides FW update. It is more difficult, more expensive but it can provide a more flexible solution.
If it will be solved with some MCU, then the best way would be UAVCAN.
Questions
- Would there be interest in such a thing?
- Prefered interface?
- Optimal maximal lighting of LEDs (current requst per channel)? Proposal of light sources?
- Optimal number of power outputs? (It will be possible to use multiple units paraelly)
Any other comments, suggestions, comments are very welcome!