ESP32-HUB75-MatrixPanel-DMA/fillrate.md

Estimating fillrate

Here are some results of simple tests on filling DMA buffer with data. Filling DMA buffer requres lot's of memory operations on a bit level rather than doing simple byte/word wide store and copy. And it looks like it's quite a task both for esp32 core and compiler. I've done this while optimizing loops and bit logic along with testing compiler results.

So the testbed is:

• Matrix modules: 4 x FM6126A based 64x64 modules chained in 256x64

A testpatters sketch:

• allocating single DMA buffs for 256x64
• allocating (NUM_LEDS*3) bytes for CRGB buffer
• measuring microseconds for the following calls:
  • clearScreen() - full blanking
  • fillScreenRGB888() with monochrome/gray colors
  • fill screen using drawPixel()
  • filling some gradient into CRGB buff
  • painting CRGB buff into DMA buff with looped drawPixelRGB888()
  • drawing lines

	clearScreen()	drawPixelRGB888(), ticks	fillScreen()	fillScreen with a drawPixel()	fillRect() over Maxrix	V-line with drawPixel	fast-V-line	H-line with drawPixel	fast-H-line
v1.2.4	1503113 ticks	9244 non-cached, 675 cached	1719 us, 412272 t	47149 us, 11315418 ticks	-	24505 us, 5880209 ticks	-	24200 us	-
FastLines	1503113 ticks	1350 non-cached, 405 cached	1677 us, 401198 t	28511 us, 6841440 ticks	10395 us	14462 us, 3469605 ticks	10391 us, 2492743 ticks	14575 us	5180 us, 1242041 ticks

to be continued...