Easymini strange behaviour

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donalquinn

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Nov 21, 2023
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Location
Barcelona, Spain
Hi all - hoping someone can help me understand whats going on with my Altus Metrum Easymini. I flew it first back in March successfully, deploying both charges. It flew twice that day as after my flight I lent it to a student team and it worked great for them too.

However, in preparation for yesterdays flight I noticed that it was behaving strangely. Plugging in the same battery (3.7v LiPo bought from Altus with the Easymini) it was registering 7.2 V instead of the usual 3.7V. Figuring it must be the battery I bought another 3.7V LiPo but it gave the same result. I updated the firmware on the device and the Altus software on my laptop but no change. Testing both batteries with a multimeter showed that they were both actually at 3.7V as they should be.

I wasn't able to test fire any charges until I got to the launch field but once there I set everything up for a static test and noticed that instead of saying "Ready" it said "Unknown" and then failed to fire. Obviously I didn't launch but now I don't know what to do with it.

Any advice?
 
Hi all - hoping someone can help me understand whats going on with my Altus Metrum Easymini. I flew it first back in March successfully, deploying both charges. It flew twice that day as after my flight I lent it to a student team and it worked great for them too.

However, in preparation for yesterdays flight I noticed that it was behaving strangely. Plugging in the same battery (3.7v LiPo bought from Altus with the Easymini) it was registering 7.2 V instead of the usual 3.7V. Figuring it must be the battery I bought another 3.7V LiPo but it gave the same result. I updated the firmware on the device and the Altus software on my laptop but no change. Testing both batteries with a multimeter showed that they were both actually at 3.7V as they should be.

I wasn't able to test fire any charges until I got to the launch field but once there I set everything up for a static test and noticed that instead of saying "Ready" it said "Unknown" and then failed to fire. Obviously I didn't launch but now I don't know what to do with it.

Any advice?
I don't visit this site often, but a friend sent email letting me know of your question.

The symptom you describe is likely caused by a damaged resistor in the divider used to measure the battery voltage. With the battery voltage circuit reading too high, the pyro status going to 'unknown' makes sense since the higher than expected battery voltage is fooling the code into thinking the igniter is high resistance.

To confirm this, you could set up the board with a USB cable to a computer and use our ground station software to 'monitor idle', then short one of the pyro channel screw pairs. If the igniter voltage is relatively close to what you know the battery voltage to be, then it's just the battery voltage measuring circuit that's bad and the board should continue to work just fine otherwise.

If that's the case, and you or someone near you is comfortable replacing an 0402 SMT resistor, the divider in question is made up R12 100k and R13 27k. I'm also willing to fix it for you, though I'm backed up enough right now that I can't promise rapid turnaround. If you want to pursue that path, use the 'contact us' form at shop.gag.com and send me the details including board serial number if you have it, and I'll open an RMA for you.

Thanks for your interest in Altus Metrum products!

Bdale
 
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