This is a discussion re the bad Accel, Gyro and Baro values that we're seeing with ArduCopter-3.1. The increase in the SPI bus speed from 500khz to 8Mhz has exposed a hardware problem on some boards. That hardware problem is that the 3.3V regulator has been blown so all sensors are running at 5V instead of the intended 3.3V.
How have these regulators been burnt out?
- Attaching a radio receiver or MinimOSD to the APM while the APM is only powered through the USB (see video below)
- Some clone boards seem to come from the factory with blown regulators. 3DR boards might also come with blown regulators although they do a specific check of the regulator as part of the regular QA process.
- It is not (as far as we know) actually caused by the AC3.1 software itself, it just exposes the problem. You could prove this to yourself by checking the 3.3V regulator (see video above) before and after the upgrade.
How can we fix the regulator?
Option #1: If it's a new board (so that it's less likely you burned it out yourself) you could report the problem to the retailer that sold you the board and ask for an replacement. If it's 3DR it's called an "RMA".
Option #2: if you're handy with a soldering iron you can replace the regulator yourself. On the APM2.5.2 (and higher) boards it's not that difficult. On the APM2.5 it's far more difficult.
For APM2.5.2 : TPS79133DBVR
For APM 2.5: MIC5219-3.3YML TR
How can I stop it from happening again?
Do not connect any devices such as a radio receiver, MinimOSD, GPS, etc while the APM is powered especially while powered only through the USB cable.
Attaching a 100uF capacitor across any of the APM's radio input's 5V and GND pins will stop the regulator from being blown by plugging in a receiver. video here!
There are very few reports of regulators being blown twice and no reports of it ever failing in flight.
Below are some graphs of the types of values that we are seeing on these boards.
Replies
Hansaka, thank you for the photos.
Now, a question... is there any chance that you pulled the shell off the board while trying to disconnect the the cable? I have done that before. You can push the shell back on, but possibly put it backwards. Any chance that happened?
Just want to be sure that we have a real situation here.
Sorry for my English and the accent
Well anyone who buys from those sellers doesn't deserve it any better. This one is a real extreme example - looks like the seller is himself not sure what he is selling. Versions and pictures from multiple products all mixed up - how would a buyer know what he gets?
Don't those clones go for $60 nowadays and shipped from the US?
Philip, I was going to mention that fact. 3/4 of the pictures there are of 3DR product. The only one that shows what you're really getting, has a connector backwards.
But you're preaching to the choir. When you can get a full-featured auto-pilot for $200, I really don't understand the desire to save a few bucks buying from a shady supplier. This stuff is complicated enough without worrying about this.
Not that everything is perfect all the time from 3DR. But the world of these clones seems SO much worse.
A lesson in open Hardware..... These sellers cannot call it ArduPilot, they can't show pictures of other brands when selling a different item.
Buyer beware.... What is your plane worth? What is your time worth? What are you saving buying a clone? These Suppliers DO NOT support this community, so why support them?
Wouldn't that explain why some people have a connector which is wired back to front?
BTW I agree, the pic you showed has the connector soldered the wrong way round!
Don't you just love Chinese quality control....
sure, I'll post something tonight. Im in a class right now ;)
Well, then get back to your studies! ;)
Thanks for the note. Another piece to the puzzle. Probably not the silver bullet, but another potential cause of problems.
SOLVED: Link to the original post
http://diydrones.com/forum/topics/the-problem-is-not-the-3-3-regula...
I read your thread Guaifi. I am not sure exactly what you did. I do not have that much of understanding of that board.
However let's assume that you found the problem and that would be the real fix. Then how would you explain that all those people that have a blown regulator replaced their regulators and their boards started functioning properly?
I am not trying to be negative at all. If what you describe is the real issue, I will be so happy. I am just trying to arrive at a logical conclusion from what you are saying and what we have in our hands so far...
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