SSD1307 dma

[AndrewCapon]

This also includes: #624

Added DMA transfers for data transfers to reduce cpu overhead.

display.h has a new pure virtual bool UpdateFinished(), returns true if the update has finished.

oled_display.h implements UpdateFinished() and calls the driver.

SSD130x4WireSpiTransport has been altered to support basic chained DMA via the finished callback, Config now has a useDma flag to enable DMA.

Some times:

Using SPI Prescaler = 2

Blocking
  1492.6 us total update time and Cpu

Dma
  Total update time = 1549.3us
  Cpu = (12.9us*16) + 0.3us = 206.7us

[github-actions]

Test Results

151 tests  ±0   151 ✅ ±0   0s ⏱️ ±0s
 16 suites ±0     0 💤 ±0 
  1 files   ±0     0 ❌ ±0 

Results for commit 8a602c9. ± Comparison against base commit f7727ed.

♻️ This comment has been updated with latest results.