To see rather dramatically the differences in performance, consider the two Logic screen captures showing the SPI transfers when filling and 7735 LCD with a solid color shown in Figure 12. The upper capture measures the time for transferring 2 pixels, while the lower capture measures the time for transferring 128 pixels. The theoretical peak is 12x106/16 = 750; 000pixels/second for a 12 MHz SPI clock. Without DMA, our transfer rate is 1/20x10