Function to determine altitude from atmospheric pressure

[TomD53]

Task for @nikiexpo

Create a new branch for this

Please add header file(s) to the lib/shared folder

Add some native unit tests for the function that can be run using the pio test -e native command

Any questions please ask here or on discord!

[nikiexpo]

Finished writing the basic feature, can calculate altitude from pressure theoretically up to 80km, but need to write some tests, but is there any additional feature that needs to be added to this?

[TomD53]

Sounds good, please make some commits to a separate branch and we shall do some code review

[nikiexpo]

Done, will send the additional files and math working in the discord

[nikiexpo]

ICAO_standard.pdf Reference

[TomD53]

Unit tests:

• For each layer of atmosphere, pre calculate 3 data points using a different tool (by hand, using ambiance python lib), and test that the output is correct
• Test edge cases on transition from one layer to the next, make sure there are no strange discontinuities

The above two tests should run in native environment

• Also would be good to produce a graph of the output using python, look up cpython

Please add tests for anything else that could go wrong

[TomD53]

Please also add a page in the docs folder to explain how this class works and add doxygen strings above each function/class to describe how they work and inputs/outputs

Refer to the documentation guide: https://mras.sunride.space/md_docs_documentation_guide.html

[nikiexpo]

[TomD53]

TODO list:

• MD file containing documentation
• Add unit tests for extreme cases (0 pressure and pressure > 101325)
• Rename to Atmosphere

[TomD53]

Above 101325Pa set altitude to 0

[TomD53]

Updated view of graph with grid and higher x-axis resolution of 1Pa

[TomD53]

Zoomed in view of discontinuity at P=101325, to be fixed by setting altitude=0 when P>101325

[nikiexpo]

Done

[nikiexpo]

@TomD53 Where do I put the md file, do i create a new folder within docs/

[nikiexpo]

nevermind, I think I got it :')

[nikiexpo]

IGNORE, testing something

$\text{if} \beta \neq 0$ $$H = H_b + \frac{T_b}{\beta} ((\frac{P_b}{P})^{\frac{\beta R}{g_0}} - 1)$$ $\text{if} \beta = 0$ $$H = H_b + \frac{RT}{g_0} ln({\frac{P_b}{P}})$$

[nikiexpo]