Color support and next collaboration examples about epdiy

[mataide]

Hello, I have here the Kaleido display https://www.eink.com/product/detail/SC1452-FOA, let me know how I can help to test this Color filter.

[martinberlin]

Further color bugs:
Sometimes, not every render I think, a pixel shifts from R to G (or to B don’t really know) making this effect in the display:

FOUND what it is:

It seems for some weird reason the pattern suddenly changes after some rows, so it's half one pattern, half the other. To understand this in code:

uint8_t epd_get_panel_color(int x, int y, uint8_t r, uint8_t g, uint8_t b) {
  // Crazy: Add 1 more to see the line (CFA filter has displaced colors)
  uint16_t y_color_offset = 684;
    /**
     * @brief First 996 Y rows have: RBG pattern but the other rows have one pixel shifted to the right so the next
     *              684 Y rows have: BGR pattern (So I have to make this weird conditionals to get the right color)
     */
    uint8_t c = (x + (epd_height() - y)) % 3;
    switch (c)
    {
      case 0:
        if ((epd_height() - y) < y_color_offset) {
          return gamme_curve[b];
        } else {
          return gamme_curve[r];
        }
        
        break;
      case 1:
        if ((epd_height() - y) < y_color_offset) {
          return gamme_curve[g];
        } else {
          return gamme_curve[b];
        }
        break;
      default:
        if ((epd_height() - y) < y_color_offset) {
          return gamme_curve[r];
        } else {
          return gamme_curve[g];
        }
    }
}

@vroland I checked this with the microscope and it does not seem that the color filter is displaced. Can be this pixel shifting something that occurs with big buffers ?

[vroland]

Hm, maybe this is because on the frame restart hack on the LCD peripheral for displays higher than 1024 pixels? It seems weid, because in that case it should be shifted by a block of 4 pixels (1 cycle), but maybe this is correlated. What's the resolution on this display again? Right now it's set to do this after 1000 lines. Does the color line shift if you change the LINE_BATCH value in output_lcd/lcd_driver.c?

[martinberlin]

Thanks for the hint. Yes this looks exactly because of this.
Resolution is: 2232x1680 (WxH)
Setting the LINE_BATCH to 840 that is exactly half of this epd_height() then this effect of color-shifting appears on the middle of the display. Trying to set it higher than 1000 it just crashes.

It seems weird, because in that case it should be shifted by a block of 4 pixels (1 cycle), but maybe this is correlated. What's the resolution on this display again?

Sure I don't really know how many pixels are, just see that is one color shifted to the right, will do more tests and let you know.
I guess it does not have anything to do with color, right? It should be possible to see a pixel shifting in any other display after certain amount of rows (Example: the 13.3" I will try that also)
We should try also on the 13.3 (The PCB I sent you has this connector) and draw some vertical lines, check if they look all plain vertical all over the display with some magnifier lens.

[martinberlin]

Hello @mataide
If you have some information / datasheet please send it to me with a private email to martin [AT] cale.es and get a working epdiy v7 board. Then we can try something together. So far I had only this Wuxi Weifeng (DES) color displays that are sold by Good-Display.

[mataide]

@martinberlin Done. Let me know if you got my email. I am very interested in making it work, and I do have contact with the EINK Engineers, so hope that I can help you with this.

[mickeprag]

Is the kaleido display different from the one you have @martinberlin?
@mataide Where did you get it from?

[martinberlin]

I'm quite sure the colors arrangement is not the same. But we need to try it so first thing I will do is to sell one of my v7 boards to him so he can try it out. And tonight will take a deeper look to the datasheet and check if the Pinout is the same as v7 current 16 bit, 40 pin connector.