all columns shifted one pixel left, column 0 is shown on right side of panel

[Markusenz]

Thanks for this work, I plan to use that lib as it works best of all I saw. However one thing I cannot easily find how to correct: I use a standard p3 panel 64x32, 1/16 scan. All works so far, but all pixels with x=0 show on the rightmost column instead of the leftmost, and all pixels with x=63 show on column 63 instead 64. So all pixels are shifted left one column, and the leftmost appears at column 64.

I wonder why since my panel is standard and I also used it already with other libs. Thanks in advance!

[Markusenz]

Another problem is that the Panel starts to show ghosting as soon as WiFi is active (as soon as the ESP32 joins an access point), which makes it useless for me...

[mrcodetastic]

Can you post an example sketch of your code ? Ghosting is probably caused by electrical interference due to the wiring - not much that can be done there. What module are you using?

[Markusenz]

Thanks a lot for your reply. I am using a standard NodeMCU from aliexpress. In the meantime I updated to current ESP32 Arduino core 1.0.1, and the ghosting when using WiFi has gone. However I still see the problem with columns shifted one pixel to the left. I attach the link to the picture showing that, and my code. I set one pixel at (0,0), which you see in the picture appearing in upper right corner, and in addition one ghosting pixel right side 16th row: https://imgur.com/a/wBa1YCS

#include <ESP32-RGB64x32MatrixPanel-I2S-DMA.h>

const byte ROWS=32;
const byte COLUMNS=64;

#define R1_PIN  17
#define G1_PIN  16
#define B1_PIN  4
#define R2_PIN  0
#define G2_PIN  2
#define B2_PIN  15

#define A_PIN   21
#define B_PIN   19 
#define C_PIN   18
#define D_PIN   5
#define E_PIN   -1

#define LAT_PIN 3
#define OE_PIN  23
#define CLK_PIN 22

RGB64x32MatrixPanel_I2S_DMA matrix; 

void weatherDemo() {
  byte br = 127;
  auto white = matrix.color444(br, br, br);
  auto red = matrix.color444(br, 0, 0);
  auto cyan = matrix.color444(0, br, br);
  auto blue = matrix.color444(0, 0, br);
  matrix.fillScreen(matrix.color444(0, 0, 0));
  matrix.setTextWrap(false);
  matrix.setTextSize(2);
  matrix.setCursor(2, 1);
  matrix.setTextColor(white);
  matrix.print("12");
  matrix.print(":");
  matrix.print("34");
  matrix.setCursor(2, 16);
  matrix.setTextColor(red);
  matrix.print("abcdef");
  matrix.drawPixel(0, 0, matrix.color444(br, br, br));
}

void setup() {
  Serial.begin(115200);
  matrix.begin(R1_PIN, G1_PIN, B1_PIN, R2_PIN, G2_PIN, B2_PIN, A_PIN, B_PIN, C_PIN, D_PIN, E_PIN, LAT_PIN, OE_PIN, CLK_PIN );  // setup the LED matrix
  matrix.fillScreen(matrix.color444(0, 0, 0));
  weatherDemo();

}

void loop() {
  delay(100);
}

[Markusenz]

When I set a green pixel at (0,23), the pixel is shown also on the right side, and the ghosting pixel one row above with reduced intensity, see second picture on that page: https://imgur.com/a/wBa1YCS

matrix.drawPixel(0, 0, matrix.color444(255, 255, 255)); matrix.drawPixel(0, 23, matrix.color444(0, 255, 0));

[mrcodetastic]

In line 251 of ESP32-RGB64x32MatrixPanel-I2S-DMA.cpp, there is:

        // need to turn off OE one clock before latch, otherwise can get ghosting
        if((x_coord)==PIXELS_PER_LATCH-1) v|=BIT_OE;

Can you comment out this bit and see what happens?

If that changes nothing, on line 236 there's:

       // drive latch while shifting out last bit of RGB data
        if((x_coord) == PIXELS_PER_LATCH-1) v|=BIT_LAT;

Can you change it to:

       // drive latch while shifting out last bit of RGB data
        if((x_coord) == 0) v|=BIT_LAT;

And see what happens?

I can't replicate this issue with my panel. Not all of these panels are made exactly the same it seems.

Thanks.

[colonelwatch]

Hello, I see this issue went stale, but I have a panel with a similar problem. All of the columns are also shifted one pixel left, where column 0 is on the right side of the panel. I don't know if this is relevant, but there is also a little bit of vertical ghosting in column 0 (nowhere else). My panel is 64x64 and a MBI5124 variant, and I put together my code from the examples.

I see that you mentioned some possible fixes before you closed the issue, but I can't find those lines of code in the most recent release.

#include <ESP32-HUB75-MatrixPanel-I2S-DMA.h>
#include <FastLED.h>

// Configure for your panel(s) as appropriate!
#define PANEL_WIDTH 64
#define PANEL_HEIGHT 64    // Panel height of 64 will required PIN_E to be defined.
#define PANELS_NUMBER 1   // Number of chained panels, if just a single panel, obviously set to 1
#define PIN_E 32

MatrixPanel_I2S_DMA *dma_display = nullptr;

uint16_t colorWheel(uint8_t pos) {
  if(pos < 85) {
    return dma_display->color565(pos * 3, 255 - pos * 3, 0);
  } else if(pos < 170) {
    pos -= 85;
    return dma_display->color565(255 - pos * 3, 0, pos * 3);
  } else {
    pos -= 170;
    return dma_display->color565(0, pos * 3, 255 - pos * 3);
  }
}

void drawText(int colorWheelOffset)
{
  // draw text with a rotating colour
  dma_display->setTextSize(1);     // size 1 == 8 pixels high
  dma_display->setTextWrap(false); // Don't wrap at end of line - will do ourselves

  dma_display->setCursor(5, 0);    // start at top left, with 8 pixel of spacing
  uint8_t w = 0;
  const char *str = "ESP32 DMA";
  for (w=0; w<strlen(str); w++) {
    dma_display->setTextColor(colorWheel((w*32)+colorWheelOffset));
    dma_display->print(str[w]);
  }

  dma_display->println();
  dma_display->print(" ");
  for (w=9; w<18; w++) {
    dma_display->setTextColor(colorWheel((w*32)+colorWheelOffset));
    dma_display->print("*");
  }

  dma_display->println();

  dma_display->setTextColor(dma_display->color444(15,15,15));
  dma_display->println("LED MATRIX!");

  // print each letter with a fixed rainbow color
  dma_display->setTextColor(dma_display->color444(0,8,15));
  dma_display->print('3');
  dma_display->setTextColor(dma_display->color444(15,4,0));
  dma_display->print('2');
  dma_display->setTextColor(dma_display->color444(15,15,0));
  dma_display->print('x');
  dma_display->setTextColor(dma_display->color444(8,15,0));
  dma_display->print('6');
  dma_display->setTextColor(dma_display->color444(8,0,15));
  dma_display->print('4');

  // Jump a half character
  dma_display->setCursor(34, 24);
  dma_display->setTextColor(dma_display->color444(0,15,15));
  dma_display->print("*");
  dma_display->setTextColor(dma_display->color444(15,0,0));
  dma_display->print('R');
  dma_display->setTextColor(dma_display->color444(0,15,0));
  dma_display->print('G');
  dma_display->setTextColor(dma_display->color444(0,0,15));
  dma_display->print("B");
  dma_display->setTextColor(dma_display->color444(15,0,8));
  dma_display->println("*");

}

void setup() {
  HUB75_I2S_CFG mxconfig;
  mxconfig.mx_height = PANEL_HEIGHT;      // we have 64 pix heigh panels
  mxconfig.chain_length = PANELS_NUMBER;  // we have 2 panels chained
  mxconfig.gpio.e = PIN_E;                // we MUST assign pin e to some free pin on a board to drive 64 pix height panels with 1/32 scan
  mxconfig.driver = HUB75_I2S_CFG::MBI5124;
  mxconfig.i2sspeed = HUB75_I2S_CFG::HZ_10M;

  dma_display = new MatrixPanel_I2S_DMA(mxconfig);

  dma_display->begin(); // use default pins
  dma_display->setPanelBrightness(64);
  dma_display->setLatBlanking(2);
}

uint8_t wheelval = 0;
void loop() {
  drawText(wheelval);
  wheelval +=1;

  delay(20); 
}

[ovdessel]

Experienced the same issue as the above comments. First column (x_coord = 0 ) was shifted to the right side of the board rather than the left.

The solution involved editing ESP32-HUB75-MatrixPanel-I2S-DMA.cpp line 366

x_coord = ESP32_TX_FIFO_POSITION_ADJUST(x_coord)+1;

[mrcodetastic]

Experienced the same issue as the above comments. First column (x_coord = 0 ) was shifted to the right side of the board rather than the left.

Did you try adjusting the 'clkphase' value?