We have a fairly important project - building an 26' Xwing fighter to raise money for STEM programs. However it needs to run error-free during demonstrations and, unfortunately, there are issues we cannot find workaround. They are listed below in the order of importance (high to low) and any input would be appreciated:
NRF24L01 wireless module works great when it does. Unfortunately, every 5 minutes it stops working and needs "to be rested" for another 5-10 minutes before it starts reacting again. One is on fully isolated Arduino (separate battery, using optocouplers to communicate with other components). Would you have any suggestions how to troubleshoot? Is there a better quality controller for wireless communication?
On the same isolated Arduino, we have Adafruit_MCP4725 DAC. Already a second one failed. Is there a more reliable alternative?
Isn't such a large plain obliged to follow certain rules, be tested and certified?
Using Arduinos sounds like exceeding the limits for those controllers.
Please correct me if I'm wrong.
But now realize this isn't actually meant to ever fly!
Please post a schematic and more information about how the "flight" electronics are powered and wired and arranged physically. It sounds like you have some issues that are coming from poor or no design.
Things shouldn't work, then not work or need to rest or burn out capriciously &c.
Thank you, Alton,
The motor is 24v PM8018-RA3020T 41490 | Groschopp with 20-1 gearbox. It's regular brushed motor to be controlled by PWM. There is one on each of the rear wheels.
As far as the wireless controller, yes, having something well-designed will be great but I cannot find anything if you can point me in a right direction. Ideally, bidirectional (but not critical) and ability to "read out" received signal by Arduino so that we can control the rest of the set up. No budget constraints up to couple hundred dollars as long as it works well.
P.S. for the context - how Arduino will be used: it will be used to open and close wings, measure steering angle and send different speeds (through DAC) to left and right motors not to overload them during sharp turns, etc. Initiate different thruster patterns, etc.
which runs on many transmitters. It provides full telemetry.
The TX needn't cost that much and can be fully hand-made for that matter. Just depends on what kind of fun you want to have.
If you buy a pre-built compatible transmitter, get some ideas of what you will need in addition to the joysticks, and spend as much as you can (!), there is a real difference between the toys $50 and the professional units 2, 5, 10 and 20 times the cost.
$100 should give you a choice of many good enough TXs.
In the aircraft, the receiver will supply a serial formatted data stream that includes all the channel information. This can be decoded by the Arduino, giving it all the numbers and switch positions &c.
I don't use opentx, so I don't know if it provides multiple PWM directly. There are decoders that can go from serial to PWMs, but you did say you want/need the Arduino in the loop.
Add Arduino to any google searches you do.
Also, check out
which is sprawling mass of infortmation but lotsa smart experience ppl live over there.
The packets sent are protected by a CRC of the payload and a network ID appended to the end of the packet. The chance of a foriegn packet being received and corrupting control is remote.
There are options for simple protected send, send until acknowledge and send and request data.
Runs on UHF LoRa for stupid long range, or 2.4Ghz LoRa for fast no duty cycle limit control.
So far all known sales of LoRa devices are geniune Semtech produced, there is none of the dodgy clones that seems to infect the NRF24 World.
Thank you, again. Here is the earlier post about the motor controllers with more details. I can directly apply PWM to 555 chips on the board but was told that I would be bypassing many important controls (overvoltage or overcurrent protection, etc. ). So, using proper POT input on the controller was recommended. This may not be correct but at least that's how I understood it. But, getting industrial controllers (since one failed) along with industrial DAC would be really preferable at this point.
For the wireless controllers, I will look at the links and see what can be done - at this point the goal is to finish this quickly and raise money. I know if I do it myself it will take years and going with a pre-built options will be preferable. Thanks for the links to the RC group.
Demo/launch will happen as soon as we are able to run it reliably, hopefully, in March or April. We are in Atlanta. I will be posting updates on Twitter if you follow. Here are direct links to few videos. Please spread the word:
I think I know potential Achilles hill and will try to address it first to see if it helps with the wireless. Here is the system description:
The main system is 24/12 v with powers up to 60amp and few other "non-critical" arduino's on that same power grid.
the main Arduino (with NRF24) is fully is isolated with a separate battery and at least 2 feet away from anything else with no wires crossing except:
connection to 5v 8-channel relay switch 2 feet away. the relay is powered separately and no ground connection. Wires from Arduino go directly to relay without crossing anything in it's path.
2 wires go to another Arduino that is on the main power grid with PC817 optocouplers. The optocouplers are on the wireless Arduino shield (so, wires from the other Arduino come all the way to the main Arduino but they are directly connected to optocouplers and nothing else).
power/ground wires from DAC go directly to motor controllers' POT input. So, technically, they aren't isolated but I couldn't find another way and here is the discussion that recommended going that route.
There is another opto-isolated connection to 5v 4-channel relay about 15 feet away with 3 wires (5v and 2 signal wires) running alongside the main power grid wires. this may be my issue and may need to move that relay closer so that signal wire doesn't cross anything on the way?
Lastly, a manual switch that activates 12v relay to turn on the entire main power supply on is running within 2 inches of the wireless Arduino. It never crosses it, just approaches within 2 inches and then turns around.
P.S. I download Fritzing but wasn't able to finish the diagrams - still learning the tool.
I’m off to the beach, I will review your remarks later.
Fritzing has sorta a bad rep around these parts, so maybe pick a different tool… google fritzing to taste the hate.
Opinions vary.
I find a good hand drawn schematic, paying attention to the basic conventions, to be more than adequate in most cases. No tool to learn.
If you don’t know what goes into a good informative and easily read schematic, google and find a few places that outline the basics, it’s fairly straightforward.