28084 ePaper Black Screen?

CJMJ

Why does the updateDisplay(ePaper) call make the screen go black then white again? Because it looks like the text is already written to the white screen before the black screen appears.

iseries

Yes, I find that annoying as well. The graphics controller is doing that and I think it's to prevent ghosting. I'm not buying it.

Mike

Roy Eltham

This is the epaper display itself when it refreshes the display.
The code just tells it to update, and then the on board chip/logic of the display does all the flashing and whatnot to update the display.

CJMJ

Take a look at this video:

The IL3820 is being updated without the flashing. I wonder if the display has different refresh modes.

CJMJ

I have another question. Still trying to understand the operation of the IL3820. In the IL3820_update.c file, after you write the Display Update 2 command, you write a data byte of 0xC4. Am I correct in assuming this is a parameter of the command? If so, I don't see an 0xC4 parameter in the datasheet.

// Update display
il3820_spiWrite(mask_cs, mask_sdi, mask_clk, mask_dc, IL3820_DISPLAY_UPDATE_2, 0);
il3820_spiWrite(mask_cs, mask_sdi, mask_clk, mask_dc, 0xC4, 1);

iseries

To update my display I wrote my own driver and based on the very poor documentation I could find on the IL3820 if it even uses that module.

I have tried several different modes and code and I still see flashing. Need better documentation on the chip used to drive this ePaper display.

Mike

Roy Eltham

The number display portion of that video is likely using the partial update functionality. I'm not sure if whatever you are using for a driver has that option.

You can see it does do the black then white flashing when doing full updates.

CJMJ

I agree the documentation could be better. It could do a better job explaining the function of each command.

I don't remember seeing any partial update functionality in the SimpleIDE IL3820 library. I wanted to use the 28084 similar to the way it's being used in the first part of the video (above). Updating variables in realtime. You can see in the video that there is a slight flicker between each updates. Also, I'd like to find that LED numbering capability, being used in the upper right hand corner of the display.

I ran across an issue on GitHub about the IL3820 flicker. It had something to do with using a different LUT for better performance and less flicker.

https://github.com/olikraus/u8g2/issues/347 "Fast and nearly flicker free LUT"

It's about halfway down the page. I'm still trying to understand the function of the waveform produced by the LUT.