Update README.md

README.md

@@ -4,4 +4,18 @@ Will draw Adafruit GFX compatible fonts, lines, squares, and it will also fill a
 
 Made for ST7920 with my own driver library, but it should be pretty universal, it just needs draw and clear functions taking x,y coords of a pixel + some user context.
 
-Idk why I added a readme, it's pretty self documenting. Maybe i'll break this into it's own git repo and add it as submodule, along with the disp driver.
+The API is pretty self-explanatory, but just in case
+
+```c
+const gfx_canvas_t canvas = {
+	.ctx = &dev,
+	.draw_pixel_callback = st7567_draw_pixel,
+	.clear_pixel_callback = st7567_clear_pixel,
+};
+
+const GFXfont *font = &FreeSans9pt7b;
+st7567_clear(canvas.ctx);
+gfx_fill_box(&canvas, 40, 40, 8, 8, false);
+gfx_draw_string(&canvas, font, 0, 16, "Hello", false);
+st7567_update_screen(canvas.ctx);
+```