Altus Metrum's EasyMini - How to compile after a simple mod to the firmware

UAEFOX

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Hello my fellow Rocketeers. This is my first Thread, so I hope I'm putting it in the right place, apologies to the mods if I am not.

I have had the pleasure of getting into this hobby only very recently. Where I live you cant get any supplies like you have access to in the states. I have not let that slow me down though, I have had a few successful ballistic launches under my belt hitting just under 300m after many many many failed attempts as I have had to design and test many iterations on the body, fins, cone, and especially the motor itself and its contents. Now that I have reached to this point it has gotten too scary trying to launch without a recovery system, as its in your sights for less than a seconds, followed by 4 seconds of euphoria and happiness, 10 seconds of, oh ohh, where is it...where is it going, to, ok, it should have hit the ground by now..i'm OK!...where did it go! and then spend between 30 to 45 minutes trying to find the remains :) I do this far out in the desert, so I'm the only one at risk, as well as the vehicle that got me there..I digress..

OK- so, my problem: I have a few Easy Mini's. 1 has already broken to bits after a failed parachute deployment..it never triggered the powderless flakes in the parachute deployment can. ( I cant get BP here..I could make it but figured my other plan might be simpler. I was wrong. I should just make my own BP, but I love to learn , so I'm taking the trickier route and learning!) The issue I found is that the EasyMini only opens the battery power to the Apogee terminal ( to blow the Charge) for 50ms..thats 5% of a second. I have to make my own igniters, and after a lot of Arduino testing, that 50ms is way to short to heat up the nichrome enough to heat up the powderless flakes to ignite, I need at least 200ms, and would prefer 300ms. I emailed Keith and he said that it is possible to modify the code, and would be simple to do :) just needed to download Debian, GNU GCC, and that students have done far more complex things. Now just to be clear I have no experience with code, software, compiling, to me C was pretty much Chinese. I will not get into Debian, or the reading I had to do to figure out how to download and use it, but that was tricky already.

In the end...I found the file that holds the code to change the 50ms to the 300ms, and saved it. Now for the life of me, and I have been trying I have no idea how to figure out what to do next, what files to compile, how to include all the files, and how to get it all into a .ihx format for me to try to flash into the hardware. Can somebody please please help! I have a rocket that has been sitting infront of me for almost 2 months now, ready to go as soon as I figure this out!

Thank you all for any help you can offer in advance!

Best regards,

UAEFOX
 

UhClem

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You have a long way to go.

In the top level of the AltOS files there will be a file named INSTALL which has compilation instructions. The basic steps are pretty easy but complicated by the fact that it is dependent on many other things being installed on your system. I don't think I even managed to track them all down.

Some of those parts are required to build things (the GUI for example) that you aren't interested in. But the build process does the whole thing.
 

UAEFOX

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Thanks David. I have tried to clear many errors, the last one being that I couldn't locate the needed Kalman.h file it seemed to be looking for. I would appreciate if anyone has done this, or willing to help. All I need changed is in thew ao_Ignite file, where I change the definition of 2 items:
1- the Ignite time from 50ms to 300ms
2- The redundancy from 2000ms to 1000ms

Those are the only two things I need changed in that file, the rest to be as it is. Any software guys out there?
 

UhClem

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Kalman.h, if I remember correctly, is created by a program during the build process. See src/util.
 

OverTheTop

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I feel your pain UAEFOX. I wanted to change one parameter that increased the logging rate for the extra four pyro channels. Getting the tool chain to build wasted a lot of time and in the end I gave up. Too much other important stuff going on to waste my time so fruitlessly. I hope you get your tweaks working.

Have you contacted Keith and Bdale and asked for assistance?
 

UAEFOX

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Thanks a lot for that information David, that is interesting, I will look into it.
OTT. I'm glad I'm not alone then :) Unfortunately I need to get through this, as my whole Rocket Build is waiting for it!
I have even designed and printed a whole new rocket body in parallel, and have started dabbling with bottle water rockets as the kids were getting impatient. Tons of fun for them and myself, I must say. But I am not ready to have all this work put in for a one way trip :) I have looked at tilt sensors, but feel they could get jittery during the ride up. I'm open to ideas :)
 

OverTheTop

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The TeleMega and a couple of other of their products do tilt detection. I used it a couple of years back on my O3400-M2020 flight. Worked well.

I really think you should drop Keith and Bdale a message. They are very helpful.
 

Steve Shannon

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In the mean time, you might be able to avoid rebuilding software. If your homemade igniters take too long to heat up the nichrome wires, try switching to smaller nichrome bridge wire and augment the nichrome bridge wire by dipping it in one of the compounds discussed on this site or on Richard Nakka’s site.
 

UAEFOX

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OTT - Thanks for the comment. What I actually have is the mercury type tilt switches. I'm assume the ones in the Tele are a bit more advanced and probably have filters to avoid unwanted parachute deployment. I am also still only using 34mm diameter size, so need to get everything to fit :). I have honestly tried emailing Keith directly and through the Altus Metrum site which I assume goes to both. Keith did get back to me very quickly on the fact that it was possible. But once i got stuck and was asking for further help, I have not heard back, I'm sure they are both very busy, and the reason why i signed up to this forum as I seek help.

Steve - Thanks. You are right I could try that, and I will look into the compounds you mentioned. I have tried some of them for the main motor igniters in the past but have had very little luck, the best I found was to use Nichrome, 2 lipo Cells and have the igniter wrapped in a turn or two of KNO3 saturated coffee filter.
I must confess, the design I have put together originally used a very thin wire from a 3mm light bulb that i cut the glass away from, it worked most of the time, but is a hassle as it needs to be replaced every launch. I am experimenting with an arc generator 🤪 takes a small lipo and kicks out multiK volts to create an arc between two nodes. I have managed to get this into a gorgeous compact form that I am proud of, with the nodes in the chamber, I have tested this on the ground with 300ms and it works every time, again and again and again. Issue is that with 50ms, that spark goes through the flakes during the 50ms and does not generate enough heat to ignite. As I mentioned before 200ms did the trick every time, so to be safe I'm looking to set it to 300ms. I am doing this for convenience, and experimentation. The Mechanical and Chemical sides I have figured out through lots of trial and error. But the software side it stumping me :(
 

Steve Shannon

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Perhaps you already have realized this, but mercury tilt switches or pendulum switches will not work to detect tilt in a rocket while it is flying. Acceleration due to thrust and drag are mostly one dimensional, inline with the axis of the rocket. When free falling after apogee a condition of microgravity exists and the mercury just floats.
Mercury switches can be used to stage a motor based on cessation of thrust, but there’s no protection against off-vertical ignition and such use is prohibited by Tripoli for safety reasons.
 
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UAEFOX

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Steve - Yes, that's why I am not trusting to use it :)

I'm still hoping someone comes through for me on the software side !
 

FredA

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Mercury switches can be used to stage a motor based on cessation of thrust, but there’s no protection against off-vertical ignition and such use is prohibited by Tripoli for safety reasons.

I thought mercury switches were prohibited for hazmat reasons.
Are they allowed?
I'd like to use one for a burn-out detector on a saucer.....deploy on burnout.
 

Steve Shannon

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I thought mercury switches were prohibited for hazmat reasons.
Are they allowed?
I'd like to use one for a burn-out detector on a saucer.....deploy on burnout.
The requirement as included in the safety codes simply prohibited using them to start motors:
“A-5 A rocket motor shall not be ignited by using:
a. A switch that uses mercury.
b. “Pressure roller” switches”

Of course local launch directors or RSOs may have other concerns, but at least right now all that I find documented is the safety codes.
 

mikec

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I thought mercury switches were prohibited for hazmat reasons.
AFAIK, they're prohibited because they are too easy to trip during ground prep, not because mercury is hazmat. I wouldn't want to have an ejection charge controlled that way either, but the safety code appears to allow that.
 

FredA

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AFAIK, they're prohibited because they are too easy to trip during ground prep, not because mercury is hazmat. I wouldn't want to have an ejection charge controlled that way either, but the safety code appears to allow that.

Clearly not done without a second safety switch that is enabled only once on the pad and not longer going to be touched.
 

cerving

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There are ball-contact switches that will work just as well, and aren't hazmat. You will still need some kind of pad safety switch, though... a wirelessly operated switch would be ideal because there's not chance of accidentally jarring it on the pad while you're actuating it.
 

Zbench

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You might consider a Lightning Bug DD Altimeter. I have one I picked up from Apogee components. I don’t know how long the pulse is, but when you watch it, the arc is substantial and typically even produces a small flame. It’s hard to imagine it wouldn’t ignite your material. It uses just ordinary shooter wire. The best part is you need just trim 1/4”’from the end of the wire to get it ready for the next use.

You can write the manufacturer from their website at arcignitiontech.com. They don’t specify the length of the pulse but I’m sure they would tell you if you wrote.
 

UAEFOX

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Zbench - Thank you for that link! That is awesome, its just what I pretty much put together :) their e-match version. It is interesting as it should connect with any, and so hopefully they can support, so hopefully they might have a solution ready for various boards. I will email them right away! Thank you!
 

UAEFOX

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Zbench - since you mentioned, that you have time to watch it, and see the Arc, and a flame gets produced, then its definitely long enough. The Easy Mini only opens the power gates for 50m, that's 5% of a second. Blink and you miss it. All you hear it a tick. I did a lot of ground testing, and hooked it up to an Arduino so that I could mimic the time and play around with it to test. at 50ms, it works maybe 20% of the time. But at 200ms, which is 20% of a second, so still a very short time, but this is enough to ignite my pyro. I have emailed the team at arcignition, if they have the support for the easymini software so that this works on their ematch then great. If not, i guess I will try to make some homemade BP, and if that doesn't work, i guess I'm gonna have to cough up another $150 for a new board, and get rid of the programming idea. The Lightning bug is slim enough to fit, so I guess it is a viable, but not the most feasible option. Thank you again Pete.
 

Zbench

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I dug this out and ran it through its test routine. You can check it out in the attached video. As you can see, the result is pretty impressive and might be just the ticket for your application.

Looks like you have to download the movie and then you can play it on your desktop.
 

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  • IMG_1716.MOV
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UAEFOX

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Pete, awesome! thanks for sharing! I also got a response from Arcignitiontech. Seems there is no need for any firmware upgrades to use their stuff on the EasyMini as they have incorporated a " Pulse Extender" which draws out the time the gate is open to about 400ms. Curious about how that works, I dont see any electronics other than the coil, maybe there is a capacitor hiding in there somewhere :)...so it would be the an option. $75 instead of the whole $150 and I would be able to keep my EasyMini :). I think I will go for it!
 
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