PicoMite demo on the Waveshare RP2040-LCD-1.28

Author	Message
matherp Guru Joined: 11/12/2012 Location: United Kingdom Posts: 11866	Posted: 04:34pm 01 Jan 2023         Quote   Is this a balancing act between when it is faster to write to and blit the entire buffer vs. when when it is faster to perform the individual drawing instructions "directly" on the display ... or do I misunderstand how these SPI displays work ? Not really The big issue with all these displays is "undrawing" something. Consider the demo but without the framebuffers Think of the hands of the clock. To move the second hand I need to: 1: restore the background that was under it 2: save the background where I am now going to draw it 3: draw the hand in the new position All this takes time and the result is that the hand flickers from one location to the next. This is improved if the background is a flat colour as I can miss step 2 but I still get flicker It can be improved again if I can time the moves with the displays raster but his is impossible on many displays (anything without a working MISO, and even with difficult) such as the demo display. The framebuffer solves this as I can assemble the image in a framebuffer where all these moves are invisible and then just paint the completed image (COPY) or the part that has changed (BLIT) to the actual display. Copying framebuffer to framebuffer takes less than a millisecond. Copying the complete image to the display in the demo takes 50mSec @ default CPU speed and 46 @ 378MHz