Hello Yan2,
The EPD function can be separated into two major asynchronous processes. The first is
the front end portion which is responsible for processing display updates. The second is
the function of driving waveforms to the TFT panel in order to update the screen contents
(the refresh operation).
With the EPDC_STANDARD MODE you are selecting the Waveform mode. The EPDC provides a mechanism through its histogram analysis feature (which can be run as part of any frame/region processing operations)
to allow the SW driver to characterize the region/buffer in terms of gray-map content.
For example, EPDC can determine if the update region (considering only those pixels undergoing a transition) contains only 2, 4, 8 or 16 gray levels, HW can automatically select waveform mode according to a programmed LUT holding
mapping between grey level and waveform mode. SW driver can also manually
choose the appropriate waveform update mode (e.g., when doing an update to repair
ghosting artifacts).
If you want to see further details please refer to section 13.6.3.4.2 Panel Architecture Configuration of the i.MX7D Reference Manual.
Have a nice day!
Jaime
