Problem with 2.13" "MH-ET LIVE E-ink Display

[jhnwmr]

Hello,
I designed a PCB with an ESP32 WROOM S3 as µController and connected to the E-Ink Display MH-ET Live 2.13".

The wiring between the two devices is as following:
ESP32 - E-Ink
5V - VCC
GND - GND
GPIO 11 - SDI
GPIO 12 - SCLK
GPIO 4 - BUSY
GPIO 5 - CS
GPIO 16 - RST
GPIO 17 - DC

For the first run I tested the "Hello World" example with the bw config (GxEPD2_213_GDEY0213B74). Unfortunately, no reaction can be seen on the display.
To test whether the display works, I connected it to the ESP32 Wroom 32. And it works perfectly there.
At first I thought the SPI configuration was wrong for the ESP32 S3, so I added an SPI.begin. Unfortunately without success. The display always remains unchanged with the ESP32 S3. What else do I have to change in the configuration?
Thanks!

[G6EJD]

Well it seems like you have a pcb routing error.

The pcb should replicate your connections defined in the code.

You can't run an epaper from 5v, it must be 3.3v

Check your pcb wiring

[ZinggJM]

I would need to know which board you select to compile for. There are several S3 boards available.
Then I need to know the constructor parameters you use. The parameters need to match your wiring. Post the whole constructor line.
And post the SPI.begin(...) parameters you tried to use. Did you add it before display.init() ?

[jhnwmr]

Hello,
I tested the Display also with 3.3 V at VCC, but there is no differents.
So far I have always used the “ESP32S3 Dev” board. Other functions on the PCB such as controlling leds (WS2812) work without any problems.
I have tried different variants with the initialization of the SPI bus. Before and after display.init. But without any difference.
The verbose shows me that the SPI bus has been initialized correctly with the right pins.

ESP32 Wiring and the Display wires go directly to the conncetor.

Here my code for testing:

#include <SPI.h>
#include <GxEPD2_BW.h>
#include <GxEPD2_3C.h>
#include <Fonts/FreeMonoBold9pt7b.h>

GxEPD2_BW<GxEPD2_213_GDEY0213B74, GxEPD2_213_GDEY0213B74::HEIGHT> display(GxEPD2_213_GDEY0213B74(/*CS*/ 5, /*DC*/ 17, /*RST*/ 16, /*BUSY*/ 4)); // GDEY0213B74 122x250, SSD1680, (FPC-A002 20.04.08)

void setup()
{
  //Variant I
  SPI.begin(12,-1,11,5); //No differents with SPI.begin(12,13,11,5);
  display.init(115200); 
  //Variant II
  //SPI.end();
  //SPI.begin(12,-1,11,5);
  helloWorld();
    delay(1000);
  helloFullScreenPartialMode();
  delay(1000);
  helloArduino();
  delay(1000);
  showFont("FreeMonoBold9pt7b", &FreeMonoBold9pt7b);
  delay(1000);
  if (display.epd2.WIDTH < 104)
  {
    showFont("glcdfont", 0);
    delay(1000);
  }

  if (display.epd2.hasPartialUpdate)
  {
    showPartialUpdate();
    delay(1000);
  } // else // on GDEW0154Z04 only full update available, doesn't look nice
  display.powerOff();
  deepSleepTest();
  Serial.println("setup done");
  //display.clearScreen(); To clear screen
  display.end();  // Releases SPI pins. Need to run init again to use display
}
[...]

[ZinggJM]

You don't need the SPI.begin() calls, as you use the default HW SPI pins for the boards you compile for. See pins_arduino.h.

VCC 3.3V is important. Else the level converter would feed 5V to the BUSY pin on the processor.

You might have an issue with strapping pins when connecting this display with its level converters.

Take a look at diagnostic output from Serial Monitor. And post it here.

[jhnwmr]

Thanks for your tips, I have removed the part with “SPI.begin()”. i have now experimented even more. I have found out that the problem is not the busy pin, but the DC pin. I connected this to GPIO 17 on the PCB and rewired it to GPIO 6 as a test. The display worked normally after that.
GPIO 17 is not a strapping pin and is identified as a normal GPIO with “U1 TXD”. Could it be that the serial interface is causing a problem with this pin?
Do you have any ideas as to how I can still use the GPIO 17 for the DC Pin?

Here the Serial Monitor output, it works with GPIO 6:

------------------------------------------
  Arduino Board     : ESP32S3_DEV
  Arduino Variant   : esp32s3
  Arduino FQBN      : esp32:esp32:esp32s3:UploadSpeed=921600,USBMode=hwcdc,CDCOnBoot=cdc,MSCOnBoot=default,DFUOnBoot=default,UploadMode=default,CPUFreq=240,FlashMode=qio,FlashSize=4M,PartitionScheme=default,DebugLevel=verbose,PSRAM=disabled,LoopCore=1,EventsCore=1,EraseFlash=none,JTAGAdapter=default,ZigbeeMode=default
============ Before Setup End ============
[  1088][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type GPIO (1) successfully set to 0x4202f12c
[  1088][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 6 successfully set to type GPIO (1) with bus 0x7
[  1097][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type GPIO (1) successfully set to 0x4202f12c
[  1108][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 16 successfully set to type GPIO (1) with bus 0x11
[  1118][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type GPIO (1) successfully set to 0x4202f12c
[  1129][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 5 successfully set to type GPIO (1) with bus 0x6
[  1139][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type GPIO (1) successfully set to 0x4202f12c
[  1149][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 4 successfully set to type GPIO (1) with bus 0x5
[  1159][I][esp32-hal-periman.c:141] perimanSetPinBus(): Pin 19 already has type USB_DM (45) with bus 0x3fc9741c
[  1169][I][esp32-hal-periman.c:141] perimanSetPinBus(): Pin 20 already has type USB_DP (46) with bus 0x3fc9741c
[  1209][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type SPI_MASTER_SCK (34) successfully set to 0x420096d0
[  1210][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type SPI_MASTER_MISO (35) successfully set to 0x420095f8
[  1222][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type SPI_MASTER_MOSI (36) successfully set to 0x42009520
[  1233][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type SPI_MASTER_SS (37) successfully set to 0x4200940c
[  1245][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type GPIO (1) successfully set to 0x4202f12c
[  1256][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 12 successfully set to type GPIO (1) with bus 0xd
[  1266][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 12 successfully set to type SPI_MASTER_SCK (34) with bus 0x1
[  1277][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type GPIO (1) successfully set to 0x4202f12c
[  1288][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 13 successfully set to type GPIO (1) with bus 0xe
[  1297][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 13 successfully set to type SPI_MASTER_MISO (35) with bus 0x1
[  1308][V][esp32-hal-periman.c:235] perimanSetBusDeinit(): Deinit function for type GPIO (1) successfully set to 0x4202f12c
[  1319][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 11 successfully set to type GPIO (1) with bus 0xc
[  1329][V][esp32-hal-periman.c:160] perimanSetPinBus(): Pin 11 successfully set to type SPI_MASTER_MOSI (36) with bus 0x1
We are running 2
_Update_Full : 1756000
_Update_Full : 1756000
helloFullScreenPartialMode
_Update_Part : 456000
helloFullScreenPartialMode done
helloArduino
[...]

[ZinggJM]

Maybe it is related with USB mode. You could try changing options for USB.

[G6EJD]

This is a common problem, but note once the device has been programmed the UART pin is no-longer used for serial communication with the device, but if you reassign the pin to your intended use then it should all work providing you disconnect the serial port, but then it makes communication with the device difficult in the future.
To reestablish communications with the device, typically use the boot button or set the strapping pins accordingly so the boot rom is invoked.

Nearly every pin on the ESP32 can be reassigned, but you'd need to check your choice is not one of those with a dedicated use.