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
I am 100% behind PK's experiment, but it must be tested, and proven that this does not happen with it as well.
Also, what is it glued on with?
Unfortunately I did not see your mod, if I had not placed the controller the way you explained in your mod. I put the v + v + the regulator with Vin and Vin old controller, its shape is much more effective. Also disconnect the USB Cable Positive to remove the risk that the accident occurs, I think it's more effective than capacitor 100 uf, 100% to reduce the possibility of feed apm by usb.Si for any reason we lose no main power supply by usb risk
So... funny we were just talking about Good Luck Buy a bit ago; I just received my new APM Power Module from them. 9 days to my door from Shen Zhen. Now I didn't KNOW I was buying from them; I just found a nice inexpensive PM that had good looking specs on fleaBay:
www.ebay.com/itm/281220056608
and went with it because it was within my budget.
Before you say it, YES, it IS a Power Module; it has 5.3V out rated at up to 3A from up to a 28V power source, so definitely 6S capable.
As you can see here, it's built around a MP19530N adjustable regulator. This bad boy is rated for up to 3A output from up to a max of 30V; so 7S is technically possible, though such packs aren't exactly popular.
My question is: Is this an independent design, or is it based on an authorized design I just haven't seen yet? All the ones I've seen have a separate regulator module similar in appearance to the Pololu regulator modules most of us have used for some robotic project or another.
Power is filtered with, you guessed it, ganged ceramic caps. That little pair at the 5V output measures 48.8uf at 0.01Ω ESR!
When I'm not dead on my feet, I'll fire up the old 'scope and see what that power looks like.
Cheers!
Paul
Then change the regulator 3.3v for my apm 2.6 LD1117av33.
I've connected to the mission planer and everything worked perfectly.
Will I have any problems having put the LD11117av33?.
I have also removed the usb cable + power, if the usb vcc runs out the main power apm not hurt to not having current.
Did you use my LM1117 mod :
APM LM1117-3.3 Regulator Mod
as a guide? If so, welcome to the club. :D
Right now, this mod is in Beta testing; I'm looking for folks to try it out and see. Preliminary testing is promising; I'm waiting for more gear to arrive to continue my work.
Paul
Juan, Phelec -
Look at my APM LM1117-3.3 Regulator Mod
It has detailed pictures of two different ways you can mount the LM1117 securely; either one would be an improvement both mechanically and electrically to what you have there, Jose.
Paul
Thanks for your interest, I've attached with hot glue to prevent accidents.
and removing the power to the USB cable also worked, no longer exposed to work with USB power under any circumstances
A little sloppy but it worked.
Thanks for the help and best regards.
I am running APM rover 2.45 and have verified I2C voltage as 4.60 VDC. I also have a rock & roll horizon in MP.
The controller is 3DR of 12/12/2012 vintage so no warranty. The board has flown well for over a year on my quad and I just recently moved it to my rover on 3/14. I do not know how the regulator was blown but I can clearly see the blowout (see pix). I do not normally make wiring changes with power on, but this could probably be due to operator error.
Question 1: How do I precisely identify the board? I can see no ID except AT 2560.
Question 2: Assuming I have a 2.5 board, is the MIC5219-3.3YML TR the best choice or would I be better off wiring a more robust regulator off the board?
Question 3: Should I continue using Rover 2.45 firmware after repairs?
Hi emile,
i can not think of any reason why you shouldn't use APMrover_2.45 after the repair.
APMrover_2.45 is running here without problems on apm2.5 and clones.
no problem at all.
Regards,
Linus
Phelec -
The APM 2.5.2 has a built-in compass; if you have plugged in an external one as well it can lock up the I2C bus. To use the external compass, you need to cut the trace at the External Compass bypass. Later, you can re-enable the internal compass by soldering a bridge across those two pads.
Unless what you've actually got is a cheap clone "2.6" APM: There are many clone manufacturers shipping 2.5.2 APMs with compass omitted and selling as "2.6" boards, without even bothering to change the silkscreen; they still say 2.5.2. I have a friend on RCG who just got one sold as a 2.5.2 from a reputable US vendor; he's slightly torqued.
Paul
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