m2 blinking alone, VCC at 0

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alizee
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Joined: Fri Dec 23, 2016 2:13 am

m2 blinking alone, VCC at 0

Post by alizee »

Hi there, I did try to find information but I have not found exactly this case - sorry if I missed something.

I have enjoyed my CF 2.0 for about three weeks. 2 days ago, I came back from vacation with it in a carry-on luggage and left it with the battery connected for a couple of days in my bag. Today, I got it out, impossible to push and activate the power button that seemed deteriorated. The plastic actually kinda fell apart and stayed between my fingers when I tried to get it out a little.

When I plugged in a new battery the m2 lights up for ~4sec, starts blinking at ~1Hz for ~5sec, and then blinks two times faster at ~2Hz indefinitely. Plugging it to power through USB has the exact same result.

Looking around on the forum I have seen that a classic check is to measure the current between GND and VCC. It seems that this is at 0.11V.

Do you guys have any idea what's happening?

Best,
Antoine
MCFurry
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Joined: Tue Jan 05, 2016 12:10 pm

Re: m2 blinking alone, VCC at 0

Post by MCFurry »

I experienced similar phenomena once some while ago. For me it was simply that the red wire from the battery connector had almost broken loose from the PCB. Simply stripping it an resoldering fixed the issue for me at least.
alizee
Beginner
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Joined: Fri Dec 23, 2016 2:13 am

Re: m2 blinking alone, VCC at 0

Post by alizee »

Allright, as I expected the power button was dead, and it was behaving as continuously pressed. The led blinking I saw was - I believe - the bootloader mode for the nRF24.

I physically removed the button and my crazyflie is working fine again. The only problem now is that the button is no more, so I'm left with un/plugging the battery. Since I am a complete beginner with SMDs, I couldn't really 'unsolder' the button and I believe I have removed the soldering pins on the PCB. Will I still be able to put a new one? If not, is there a pin somewhere that I can use to reset it by hand? I can't see any in the schematics ( 'SWITCH' from the nRF24 is just going to...the switch :-) )

Regarding the root causes of the problem, I still have a pending question: how did this button get deteriorated in the first place? I really believe that something happened with the battery being plugged in the whole time - is it possible?
tobias
Bitcraze
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Joined: Mon Jan 28, 2013 7:17 pm
Location: Sweden

Re: m2 blinking alone, VCC at 0

Post by tobias »

Sorry to hear about your switch. Are you sure you broke away the pad? Do you have any picture to share?

Using the battery cable to power on/off is one solution but you need the button to get into bootloader mode (if you want/need that). Something to short the SWITCH signal to GND is enough, like a pair of tweezers. Another option is to reprogram the nrf51 with another pin as being the switch, however to update the bootloader a SWD programmer is needed.
Regarding the root causes of the problem, I still have a pending question: how did this button get deteriorated in the first place? I really believe that something happened with the battery being plugged in the whole time - is it possible?
It can not deteriorate because of battery being plugged in byt maybe moist or something similar can.
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