reTerminal E1002 max SPI speed 200 khz instead of 2 mhz, is that correct or do I have a bad unit?

Products & Technology
1

I got the reTerminal E1002 color 7.3” display and the wiki Arduino examples didn’t work (nothing happened with the Seeed_GFX one and the GxEPD2 filled the screen with garbage/snow sometimes). I finally got the GxEPD2 example working, but only if I lower the hspi speed to 200000 (200 khz) from the 2000000 (2 mhz). I’ve looked around and it seems like I should be able to do 1 mhz (Home assistant configs). So did I get a bad unit/screen? Or is the example they provide just got 1 too many zeros?

I did notice that the example had MAX_HEIGHT macro that was defined incorrectly for the color display (wasn’t changed from the b/w version), so maybe the color example is just un-tested crap code…

2

Hi there,

So, I would suspect the example / software setup before the panel itself.

A few reasons:

  1. Seeed’s Arduino wiki currently shows the reTerminal E1002 GxEPD2 example using HSPI at 2 MHz, so the extra zero does not look like a simple typo in the published code.
  2. Seeed also documents a known issue where the microSD card and ePaper share the same SPI bus, and if the SD side is not initialized or disabled correctly, the display may show nothing or fail to refresh properly. They specifically recommend either using the SD enable code or removing the card if it is not needed.
  3. Since you already found that the published example had a wrong MAX_HEIGHT macro setup carried over from the black-and-white version, that does suggest the color Arduino example may not have been fully validated. The wiki does show the color example using the same generic MAX_HEIGHT pattern and the GxEPD2_730c_GDEP073E01 driver.

So no, I would not call it a bad unit yet.

I would test in this order:

  • remove the microSD card completely, or add the SD enable/init handling exactly as Seeed documents
  • keep using the confirmed-correct E1002 color driver (GxEPD2_730c_GDEP073E01)
  • keep the corrected color MAX_HEIGHT / buffer configuration
  • then try stepping SPI upward gradually: 200 kHz → 500 kHz → 1 MHz → 2 MHz

If it is solid at low speed and breaks as speed rises, that still points more toward timing / example-stack / bus-contention issues than a bad screen.

HTH
GL :slight_smile: PJ :v:

3

Thank you! It was the SD card being present. After removing it, the screen is working at 2 mhz. I should have read to the very end, but got hung-up on the basic examples not working.

Although, if it’s a know issue, it might be good to include in the first example code… :wink:

Yea, the MAX_HEIGHT issue is that they use WIDTH/8 (1 bit pixel for BW) but need to use WIDTH/2 (4 bit pixel) for 7 color. And since the ESP32-S3 has 512K of ram, it does work but uses 187.5K of ram instead of 15.625K…

// Select the ePaper driver to use
// 0: reTerminal E1001 (7.5'' B&W)
// 1: reTerminal E1002 (7.3'' Color)
#define EPD_SELECT 1

#if (EPD_SELECT == 0)
#define GxEPD2_DISPLAY_CLASS GxEPD2_BW
#define GxEPD2_DRIVER_CLASS GxEPD2_750_GDEY075T7 // 7.5'' B&W driver
#elif (EPD_SELECT == 1)
#define GxEPD2_DISPLAY_CLASS GxEPD2_7C
#define GxEPD2_DRIVER_CLASS GxEPD2_730c_GDEP073E01 // 7.3'' Color driver
#endif

#define MAX_DISPLAY_BUFFER_SIZE 16000

#define MAX_HEIGHT(EPD)                                        \
    (EPD::HEIGHT <= MAX_DISPLAY_BUFFER_SIZE / (EPD::WIDTH / 8) \
         ? EPD::HEIGHT                                         \
         : MAX_DISPLAY_BUFFER_SIZE / (EPD::WIDTH / 8))
4

Hi there,

Whew, That was a shot in the dark… But glad it’s that for sure and not a bad one,
I’m still waiting for the Live stream unit I won to Arrive, but my FOMO got me to read through the wiki.. :grin:

Do me a solid and Mark it as the Solution so others with the same enthusiasm can find it fast :slight_smile: :+1:

GL :slight_smile: PJ :v:

They are hitting the market by storm , so I’m certain more info and better hardware will be forthcoming as well. :crossed_fingers: