[avu2]

I connected an I2C HMC5983 external mag which could be correctly calibrated for use with INS13 and GPS. But in this configuration the ESC will not initialise on battery Power On (3 short bips) and motors will not spin. All systems show green and go. The ESC will correctly initialize (the normal 7 bips) and the motors will spin if the Revo is USB powered before connecting the battery. Anyone has an explanation or workaround for this ?

The setup is LP16.09 std, Revo, Ublox8 GPS with unusable disconnected I2C ext mag, I2C HMC5983 ext mag, PWM inputs, 4 x PWMsync outputs to 12A Blheli with BEC ESC, 1550mAh 3S 45C LiPo. Powering the HMC5983 external mag directly from the 5V power distribution BEC instead of the Flexi port has no effect, ESC will not initialise on battery only. Is it worth buying a 75C LiPo ?

Thank you

[Rickolas]

Open GCS and take a look at the flight data tab.  Are any of the sensors showing RED?  If they are, it will not arm and you will need to find the cause.

It's also possible that if you've just upgraded your FC and GCS to 16.09, that it has defaulted to always disarmed under the arming settings.

[avu2]

All sensors are GREEN in GCS and arming is indeed manual with the RC. GCS says and shows ARMED when done, status WS281x LED is blue, but motors will not spin due to incorrect ESC initialization at power up. This quad was flying with 16.09 before adding the external magnetometer. I tried 16.09+r711 but import 16.09 UAV settings is not straightforward, you must reconfigure a lot, so got back to 16.09 until this is settled. Thank you for the advice.

[Rickolas]

Might sound daft, but have you set the home location and calibrated the Mag?

[TheOtherCliff]

When powered only with USB, the ports are not powered, so the I2C mag is not powered.  It gets temporarily removed from the list of devices and that lets everything else work.  When you use the battery, it sees the mag and has constant problems talking to it.  Be aware that you must connect SCL to SCL and SDA to SDA.

You don't need a different LiPo.

You may want to search the forum.  I know there are some new, different mags out there and one of the programmers (mr_w) at least has a private version that works with some newer mag.

[avu2]

When I power up the Revo with USB then connect the battery and then I remove the USB from the Revo and rely only on telemetry, everything looks OK in GCS Flight Data and UAV Objects : no I2C error, ext mag showing good readings, INS13 converged with external mag only, GPS 3D fix, so I think the wiring is OK. The ext mag is correctly calibrated (green with a few yellows) and oriented with the internal mag, motors are spinning (without propellers) on output configuration test or when armed. So the advice would be to change this external magnetometer, that will take time. Until then I may try this particular power on sequence before flying. Thanks again both of you.

[TheOtherCliff]

That says "better power comes from USB" which says "try different power option on battery".

I always keep all my ESC BECs enabled.  Try leaving all the ESC red wires connected on the servo / control signal connector.

Some stand alone BECs have a 5v/6v jumper.  If you have a higher voltage option on the BEC you could try that.

Try a different type of power (different brand of BEC) on the quad.