mp-pico-solar-system

An app designed for the Pico Explorer Base board and the RV3028 Real-Time Clock breakout. The app displays the solar system's planets on the board's built-in display.

The planets are displayed (not to scale!) on simplified circular orbits. The orbit tracks for the four rocky inner planets are brighter, and the orbit tracks for the outer planets are darker. Earth is placed on a green orbit with (obviously) Mars on the nearest outer track and Venus on the nearest inner track. The date of the planetary positions is shown in the top left-hand corner of the display.

At startup the display is in Night Mode, with everything rendered in RED. Hitting "A" toggles between this mode and the alternative full colour mode.

Installation

Copy the files in the pico directory to the root of the Raspberry Pi Pico. main.py will run automatically when the explorer is switched on. Alternatively, if you don't want to commit main.py to the board you can upload the other files and use Thonny to run the app.

Using the app

At startup the current locations of the planets are displayed

• Press (and hold) Y to advance the planets, one day at a time
• Press (and hold) B to retard the planets
• Press A to toggle night mode
• Press X to exit the application's main loop

Maximum Advance is set by the program's _ADVANCE_DAYS_MAX constant (typically a year). Maximum retard set by the program's _ADVANCE_DAYS_MIN constant (typically a year). So you can display the planets either side of the current time by a year (i.e. one orbit of the Sun by the Earth).

As you hold Y or B the speed that the planets advance or retard increases, i.e. they orbit faster the longer the button remains pressed.

Demo mode

If you set _DEMO to True an automatic advancement of the orbits takes place (and the advance/retard buttons are disabled). The animation resets after a full orbit of Neptune (160 years) with a full orbit taking about 5 minutes on the Pico.

Credits

Planetary calculations have been taken from the code written by Dmytro Panin, and can be found in his pico-solar-system repository. I have used his planets.py module, but replaced the main-loop with a version suitable for the Pico Explorer Base.

Mods to 3rd party code

1. planets.py: Added #pylint: skip-file to line 1
2. main.py: Replaced to use the RV3028 and Pico Explorer Base

Anatomy of planets.py

The planets.py module is unchanged from Dmytro's original. Unfortunately it has no documentation, and I've reverse-engineered some potentially helpful documentation here...

• planets_a is a list of planet 'bitmaps' (sprites). The array has eight entries, one for each planet (Mercury to Neptune). Each array entry is a one-dimensional list of bytes that is 'interpreted' as consecutive blocks (rows) of 5-byte values for each pixel in the bitmap. The five bytes are the pixel's 'x', 'y', 'red', 'green', and 'blue' values. The bitmap size is up to 7x7 with 'x' and 'y' values ranging from 47 to 50. The pixel at 50,50 (the centre of the bitmap) is placed on planet's co-ordinate.

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