Help required from Multiwii coders

[f0x]

Hello all,

I have been reading the forum for quite a while, however this is my first post as a registered user.
My name is andrew and I have a multiwii quad which I have been enjoying thanks to the help I got from reading the forums.
First of all Multiwii is a kick-ass firmware works flawlessly for my FPV and has brought me many many joyful battery cycles in the air.

However, I am writing due to a project I started in my spare time which requires arduino coding skills (which I lack heavily).

One of my other hobbies (apart from FPV flying) is cave diving which includes the rather risky and slow process of mapping/survaying a cave line.
This includes aligning your compass with the line writing down on a waterproof wrist pad and measuring the line by hand.
All this takes your mind off your gauges, surroundings, slows you down significantly and is honestly boring.
I want to automate this process.

My project aims to develop a semi-automated cave line mapping device which I will try to describe.

The device is basically a data logger which consists of the following:

-multiwii pro flight controller (which I got from readytoflyquads)
-laser mouse optical flow sensor ( for measuring the rope/cave line length )

The device whould do the following actions:

1. Attach it to the line and start sliding it with you as you swim along.
2. measure the length of the line passing through the optical mouse/flow sensor (i've done this in hardware and code already)
3. Take a compass reading every few centimeters (1,5,10 needs testing)
4. log the distance and heading to an sd card ( done this in code and hardware already)
5. Later a map of the line will be drawn from the log file by a pc based software or script.

I am unable to code the functions which will intialize the compass and calibrate it (like the multiwii rotation calibration routine) and then take an accurate measurement of heading.
I am also unable to perform the tilt compensation with the gyro and compass.

I tried extracting the sections of code from the multiwii firmware since it already has those functions, but I am stuck for almost a month (lost in the code).

So I am asking for the community's help. Could someone write or extract the code from multiwii which starts the compass, does a calibration and outputs a correct heading in degrees (tilt compensated and with magnetic declination included).

I have this board to work with:
http://witespyquad.gostorego.com/flight ... ption.html

Currently I am using this library to get raw values from the hmc5883l successfully.
https://github.com/jrowberg/i2cdevlib

I hope I have not violated any board rules by posting this and I will be happy to provide any details if someone would like to help me.

Kind Regards,
Andrew

[haydent]

i imagine there are arduino libraries for this sort of thing ?