Created Create a custom splash screen (markdown)

Create-a-custom-splash-screen.md

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+Are you bored of the standard power on screen?
+Do you want your own image at power up to personalise your device?
+You can!
+
+Prerequisites:
+Some form of linux command line such as WSL or a bash/sh prompt
+A graphics program such as GIMP (Gnu Image Manipulation Program)
+xxd (available from your packet manager, in Debian-based systems sudo apt install xxd)
+
+Create (or load) an image
+
+Resize (or crop) it to width 240 height 304 (the LCD is 320x240, rotated 90 degrees so 240x320, with 16 pixels deducted for the top line)
+
+If you want to add text, do it after the next step so the text looks as clear as possible.
+
+Change the image to an optimised 256 colours (8 bit) or 16 colours (4 bit) palette. Consider also greyscale 8 bits, it can make a so-so image look brilliant.
+As mentioned, any text you wish to overlay should be added now.
+
+Export the image as Windows bitmap, RLE (run length encoded) if possible. RLE means that any colours the same get merged into one making the filesize much smaller.
+Save it as splash.bmp to a directory such as ~/Pictures
+
+Open a terminal window
+
+Change directory to where the image was saved (for example ~/Pictures):
+cd ~/Pictures
+Convert the image to a c++ header file:
+xxd -i splash.bmp bmp_splash.hpp
+
+Make a backup of the existing splash screen
+Change directory to the path to where you downloaded the Mayhem source eg ~/src/portapack_mayhem
+cd ~/src/portapack_mayhem
+mv firmware/application/bitmaps/bmp_splash.hpp firmware/application/bitmaps/bmp_splash.hpp.backup
+
+Copy the new splash screen to here
+cp ~/Pictures/bmp_splash.hpp firmware/application/bitmaps/bmp_splash.hpp
+
+Finally, rebuild the source and flash the HackRF One and PortaPack.
+