LEDs always glowing a little (Fix: Electrical grounding issue)

[beiyer838]

I am using a 128x64 with ICN2038S. I am not able to clear the screen completely. All the pixels seem to dimly lit. It disappears if I disconnect and reconnect my ESP32 from the HUB75E.

HUB75_I2S_CFG::i2s_pins _pins={R1, G1, BL1, R2, G2, BL2, CH_A, CH_B, CH_C, CH_D, CH_E, LAT, OE, CLK};
HUB75_I2S_CFG mxconfig(
                        128,   // width
                        64,   // height
                         1,   // chain length
                     _pins,   // pin mapping
  HUB75_I2S_CFG::ICN2038S      // driver chip
);

mxconfig.latch_blanking = 4; mxconfig.i2sspeed = HUB75_I2S_CFG::HZ_8M; mxconfig.clkphase = 0;

//dma_display->clearScreen(); //dma_display->fillScreenRGB888(0,0,0); dma_display->fillScreen(0); dma_display->setTextSize(4); dma_display->setTextColor(dma_display->color565(0,255,0)); dma_display->setCursor(1, 0); //0 dma_display->print("HELLO");

White background :

Disappeared after re-connecting ESP32 board to hub75 :

[mrcodetastic]

Looks like an electrical grounding issue. Is the ESP's and the panel grounds connected?

[beiyer838]

Yes ESP and panel share the same power source.

[beiyer838]

mxconfig.i2sspeed = HUB75_I2S_CFG::HZ_20M; The panel look like this with clock speed at 20M :

At 20Mhz, the full white background sometimes re-appear after resetting ESP32 several times. At 10Mhz, it is consistent full white background even with multiple resets. https://github.com/user-attachments/assets/053b4eb1-0b57-49e1-a187-07d242b38d42

[beiyer838]

The panel has 2 pins for GND connection. Disconnecting either one of them from ESP32 solves the problem. Thanks mrcodetastic for your guidance.