Tiler is a utility to extract tile data from a bitmap. Currently it is aimed at Foenix computers, but it is intended to become more configurable and support sprites as well as additional settings to make it more flexible.
From a bitmap it can create a tile map, with tile index data, tile definitions and extract the palette in 0rgb form.
Bitmaps can be created with GIMP, use 8-bit indexed mode and a
suitable palette. Export as .bmp with the palette included.
Run through tiler.