[DorsetFlyer]

Although the CC3D does not support GPS, I wonder if it could provide an approximation to Position Hold by double integrating the accelerometer components to obtain position. I suppose this would drift, but it could be a helpful option if you loose orientation. Automatic landing might also be possible by controlling the descent speed as is done in ArduCopter.

[Mateusz]

I am not sure ArduCopter can run on CC3D (STM32F103) with limited memory, it's rather for hardware similar to Revolution FC. When it comes to position estimation with accelerometer I found this http://www.chrobotics.com/library/accel-position-velocity

In summary, it is possible to use the accelerometers to estimate velocity and position, but the accuracy will be very poor so that in most cases, the estimates are not useful.

[DorsetFlyer]

Sorry, I didn’t mean running ArduCopter on the CC3D. I know it can’t do that. I meant that in ArduCopter, although you have GPS and barometer, the final descent speed in “Land” is set to a constant low value using the integrated vertical acceleration. This does give a remarkably gentle landing hands off. I thought that perhaps the CC3D could be programmed to do much the same thing.

I take your point about position accuracy but I was thinking that in a situation where you lost orientation, getting it to stay more or less still for a while might allow you to sort things out before you crash.

[hwh]

Anything could be done, but with an old board like the cc3d it's unlikely.   We're talking about a 5 year old board design that was discontinued  4 years ago when it was replaced by the revolution board and other F4 based boards that have way more memory.  The only reason anyone can buy them is because the Chinese took the design and started producing clones.

As Mateusz said, it has very limited memory so you'd have to remove some existing functionality to make room for new functionality. 

[DorsetFlyer]

I guess that’s right. The board is obsolete now.

[Mateusz]

I guess that’s right. The board is obsolete now.

I think CC3D has different purpose, it never meant to be anything else then racing controller, and it still serves this purpose very well as best quality/price. I am still using it, just different purpose

[TheOtherCliff]

The sensors are very accurate, but to do what you ask for more than a few seconds would require impossibly accurate sensors.