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
Well, when all said and done and the thread read it is very obvious that the hardwaredesigners of APM2.x don't know their stuff and desperately failed in delivering a solid hardwareplatform no sweet talk around that plain fact. The marketing however is splendid since there is not a single note on that subject in the shop. Not even a hint - not to say a red warning sign - for customers. So if customers don't stumble above this thread they risk crashing expensive equipment with a grin on some companies face? Did the same developers design the PIXHAWK?
Randy
As i understand it in 3.1 the buss speed was increased to 8 K i think not sure on this but my question is now is this over clocking the chipset or is it still able to handle a higher buss speed i know if it is over clocked this can cause glitches freezes in the program ETC also what is the ram in the 2.5 chipset as it needs to have room for math calq.
Also if the sensors on the board only uses 3.3 v why not just reduce it at the feed to the board if this can be done it would eliminate the bugger of soldiering that little reg on the board.
Dennis
Hi guys, sorry to ask some unrelated question but after doing some search I am helpless.
I have a few question about external compass module (HMC 5883L) for APM 2.5
Where would I post this question so I can get some answers before it gets buried down?
Please be specific (exact forum section/name etc.) so I don't get lost...
Thanks
Wow!
I just mounted my new Arduflyer 2.5.2 board into my quadcopter, installed the firmware, stepped through the MP wizard until the page where it asked to calibrate my radio. Then I connected my PPM-sum cable (correctly) and noticed that the radio input bars weren't moving. I started MP again, and then started getting "no heartbeat packet" messages. I also tried a different USB port with the same result. Then, decided to measure the voltage over the I2C port and found it to be 0.07V (on my other blown 2.5 board it was 4.6V). So it looks like I blew something again (3rd time). Are these boards so vulnerable and could connecting a receiver while it's on be enough to damage it? I'm starting to loose faith in these boards. I hope the Pixhawk is more robust.
Anyway, I can still connect via the terminal, and I can erase the eeprom, and install new firmware, but that's about it.
I've got an old 2.5 board with the tiny regulator that's blown, but not only is the regulator too small for me to replace, Digikey asks $30 for shipping.
So... if I don't use anything connected to the I2C port, is it safe to continue using the board with the 2.9.1b firmware or else use it for Arduflyer (haven't tried that yet)? I'm not sure which sensors are all affected and how bad that is.
Btw just ordered a PX4FMU+IO pair :)
I just found out the voltage regulator in my APM 2.5.2 is bad. I know i've never plugged anything in backwards, in fact I've hardly used this APM. Thankfully I can actually replace this chip myself.
Odd behavior I noted, it doesn't spike when powered via USA, only via battery/power module (tried both). I'll measure the voltage when it's on USB power to see why that doesn't cause spikes.
Randy
This has been frustrating to say the least first the quad was flying just fine an hour before upgrading the firmware to 3.1 and then not working at all i might just through in the towel on this one.
Dennis
I hope i am in the correct forum location to get an answer to a regulator question.
Well here goes i finely got a new regulator on the board it seams to be up and running i connected to the board via the usb and mission planner flight data page no longer displays bad gyro health and all looks normal when i pick up the quad and move it around the hud corresponds mission planner loaded 3.1 on the board i can get the motors to arm and spin but now i don't have GPS the little blue led dose not light but when i go into terminal screen and run test gps it shows a coordinate heading it did work the led worked before the reg went out so is there something in the new 3.1 firmware that turns it on or did it blow.
Thanks
Any drop in replacements for APM 2.5 for the regulator?
Really don't want to scroll through all the pages.
Yeah I could get a exact part replacement, but I was wondering if there is an alternative part.
Hi,
the SPI bus speed from 500khz to 8Mhz for Arduplane ????
Best ;)
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