LED Matrix Panel 64x32 is flickering / flashing (with NodeMCU)

phil2023 · January 21, 2023, 7:52pm

Hi,

I have a NodeMCU programmed with Arduino IDE so that a matrix panel (size 64x32) can be used in combination.
Since about two weeks I am struggling getting rid of some strange flickering / flashing.

I have a video which shows the PxMatrix/pixeltime....:

First half shows "effect" while programming the NodeMCU and then pixeltime.

Any idea or hint how to get rid of it?

b707 · January 21, 2023, 7:55pm

Your link is a white square rather than video

xfpd · January 21, 2023, 11:44pm

#include <Adafruit_NeoPixel.h>
#define LED_PIN    6
#define LED_COUNT  1023
Adafruit_NeoPixel strip = (LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);
void setup()
{
    strip.begin();
    for (int i = 0; i < LED_COUNT ; i++)
    {
        strip.setPixelColor(i, 0xff, 0xff, 0xff);
    }
    strip.show();
}
void loop(){}

TomGeorge · January 22, 2023, 12:02am

Hi, @phil2023
Welcome to the forum.

Can you please post your code?

Can we please have a circuit diagram?
An image of a hand drawn schematic will be fine, include ALL power supplies, component names and pin labels.
Please include your power supplies.

What are you using to power the matrix array.

Can you please post a link to data/specs of the array?

Thanks.. Tom..

phil2023 · January 22, 2023, 2:30am

Hi Tom,

Thank you for asking....

Code is...

// This is how many color levels the display shows - the more the slower the update
//#define PxMATRIX_COLOR_DEPTH 8

// Defines the buffer height / the maximum height of the matrix
//#define PxMATRIX_MAX_HEIGHT 64

// Defines the buffer width / the maximum width of the matrix
//#define PxMATRIX_MAX_WIDTH 64

// Defines how long we display things by default
//#define PxMATRIX_DEFAULT_SHOWTIME 30

// Defines the speed of the SPI bus (reducing this may help if you experience noisy images)
//#define PxMATRIX_SPI_FREQUENCY 20000000

// Creates a second buffer for backround drawing (doubles the required RAM)
//#define PxMATRIX_double_buffer true

#include <PxMatrix.h>

// Pins for LED MATRIX
#ifdef ESP32

#define P_LAT 22
#define P_A 19
#define P_B 23
#define P_C 18
#define P_D 5
#define P_E 15
#define P_OE 2
hw_timer_t * timer = NULL;
portMUX_TYPE timerMux = portMUX_INITIALIZER_UNLOCKED;

#endif

#ifdef ESP8266

#include <Ticker.h>
Ticker display_ticker;
#define P_LAT 16
#define P_A 5
#define P_B 4
#define P_C 15
#define P_D 12
#define P_E 0
#define P_OE 2

#endif

#define matrix_width 64
#define matrix_height 32

// This defines the 'on' time of the display is us. The larger this number,
// the brighter the display. If too large the ESP will crash
uint8_t display_draw_time=60; //30-70 is usually fine

//PxMATRIX display(32,16,P_LAT, P_OE,P_A,P_B,P_C);
//PxMATRIX display(64,32,P_LAT, P_OE,P_A,P_B,P_C,P_D);
//PxMATRIX display(64,64,P_LAT, P_OE,P_A,P_B,P_C,P_D,P_E);
PxMATRIX display(64,32,P_LAT, P_OE,P_A,P_B,P_C,P_D);

// Some standard colors
uint16_t myRED = display.color565(255, 0, 0);
uint16_t myGREEN = display.color565(0, 255, 0);
uint16_t myBLUE = display.color565(0, 0, 255);
uint16_t myWHITE = display.color565(255, 255, 255);
uint16_t myYELLOW = display.color565(255, 255, 0);
uint16_t myCYAN = display.color565(0, 255, 255);
uint16_t myMAGENTA = display.color565(255, 0, 255);
uint16_t myBLACK = display.color565(0, 0, 0);

uint16_t myCOLORS[8]={myRED,myGREEN,myBLUE,myWHITE,myYELLOW,myCYAN,myMAGENTA,myBLACK};

uint8_t static weather_icons[]={0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x20,0x00,0x00,0xff,0xe0,0x00,0x00,0x00,0x00,0xff,0xe0,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x07,0xff,0x07,0xff,0x07,0xff,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x20,0x00,0x00,0x07,0xff,0x07,0xff,0x07,0xff,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xff,0xe0,0xff,0xe0,0xff,0xe0,0xff,0xe0,0x00,0x00,0x00,0x20,0x00,0x00,0x00,0x00,0x00,0x00,0x07,0xff,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x20,0xff,0xe0,0xff,0xe0,0xff,0xe0,0xff,0xe0,0xff,0xe0,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xff,0xe0,0xff,0xe0,0xff,0xe0,0xff,0xe0,0xff,0xe0,0x00,0x00,0x00,0x00,0x00,0x00
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};

#ifdef ESP8266
// ISR for display refresh
void display_updater()
{
  display.display(display_draw_time);
}
#endif

#ifdef ESP32
void IRAM_ATTR display_updater(){
  // Increment the counter and set the time of ISR
  portENTER_CRITICAL_ISR(&timerMux);
  display.display(display_draw_time);
  portEXIT_CRITICAL_ISR(&timerMux);
}
#endif


void display_update_enable(bool is_enable)
{

#ifdef ESP8266
  if (is_enable)
    display_ticker.attach(0.004, display_updater);
  else
    display_ticker.detach();
#endif

#ifdef ESP32
  if (is_enable)
  {
    timer = timerBegin(0, 80, true);
    timerAttachInterrupt(timer, &display_updater, true);
    timerAlarmWrite(timer, 4000, true);
    timerAlarmEnable(timer);
  }
  else
  {
    timerDetachInterrupt(timer);
    timerAlarmDisable(timer);
  }
#endif
}



void setup() {

 Serial.begin(9600);
  // Define your display layout here, e.g. 1/8 step, and optional SPI pins begin(row_pattern, CLK, MOSI, MISO, SS)
  display.begin(16);
  //display.begin(8, 14, 13, 12, 4);

  // Define multiplex implemention here {BINARY, STRAIGHT} (default is BINARY)
  //display.setMuxPattern(BINARY);

  // Set the multiplex pattern {LINE, ZIGZAG,ZZAGG, ZAGGIZ, WZAGZIG, VZAG, ZAGZIG} (default is LINE)
  //display.setScanPattern(LINE);

  // Rotate display
  //display.setRotate(true);

  // Flip display
  //display.setFlip(true);

  // Control the minimum color values that result in an active pixel
  //display.setColorOffset(5, 5,5);

  // Set the multiplex implemention {BINARY, STRAIGHT} (default is BINARY)
  //display.setMuxPattern(BINARY);

  // Set the color order {RRGGBB, RRBBGG, GGRRBB, GGBBRR, BBRRGG, BBGGRR} (default is RRGGBB)
  //display.setColorOrder(RRGGBB);

  // Set the time in microseconds that we pause after selecting each mux channel
  // (May help if some rows are missing / the mux chip is too slow)
  //display.setMuxDelay(0,1,0,0,0);

  // Set the number of panels that make up the display area width (default is 1)
  //display.setPanelsWidth(2);

  // Set the brightness of the panels (default is 255)
  //display.setBrightness(50);

  // Set driver chip type
  //display.setDriverChip(FM6124);

  display.clearDisplay();
  display.setTextColor(myCYAN);
  display.setCursor(2,0);
  display.print("Pixel");
  display.setTextColor(myMAGENTA);
  display.setCursor(2,8);
  display.print("Time");
  display_update_enable(true);

  delay(3000);

}
union single_double{
  uint8_t two[2];
  uint16_t one;
} this_single_double;

// This draws the weather icons
void draw_weather_icon (uint8_t icon)
{
  if (icon>10)
  icon=10;
  for (int yy=0; yy<10;yy++)
  {
    for (int xx=0; xx<10;xx++)
    {
      uint16_t byte_pos=(xx+icon*10)*2+yy*220;
      this_single_double.two[1]=weather_icons[byte_pos];
      this_single_double.two[0]=weather_icons[byte_pos+1];
      display.drawPixel(1+xx,yy,this_single_double.one);
    }
  }
}

unsigned long last_draw=0;
void scroll_text(uint8_t ypos, unsigned long scroll_delay, String text, uint8_t colorR, uint8_t colorG, uint8_t colorB)
{
    uint16_t text_length = text.length();
    display.setTextWrap(false);  // we don't wrap text so it scrolls nicely
    display.setTextSize(1);
    display.setRotation(0);
    display.setTextColor(display.color565(colorR,colorG,colorB));

    // Asuming 5 pixel average character width
    for (int xpos=matrix_width; xpos>-(matrix_width+text_length*5); xpos--)
    {
      display.setTextColor(display.color565(colorR,colorG,colorB));
      display.clearDisplay();
      display.setCursor(xpos,ypos);
      display.println(text);
      delay(scroll_delay);
      yield();

      // This might smooth the transition a bit if we go slow
      // display.setTextColor(display.color565(colorR/4,colorG/4,colorB/4));
      // display.setCursor(xpos-1,ypos);
      // display.println(text);

      delay(scroll_delay/5);
      yield();

    }
}

uint8_t icon_index=0;
void loop() {
  scroll_text(1,50,"Welcome to PxMatrix!",96,96,250);
  display.clearDisplay();

  draw_weather_icon(icon_index);
  icon_index++;
  if (icon_index>10)
    icon_index=0;

  for (int xx=0; xx<16;xx++)
  {
    display.drawLine(xx+16,0,xx+16,5,display.color565(xx*16,0,0));
    display.drawLine(xx+16,6,xx+16,10,display.color565(0,xx*16,0));
    display.drawLine(xx+16,11,xx+16,15,display.color565(0,0,xx*16));
  }
  delay(1000);
  for (uint8_t dimm=255; dimm>0; dimm--)
  {
    display.setBrightness(dimm);
    delay(5);
  }
  for (uint8_t dimm=0; dimm<255; dimm++)
  {
    display.setBrightness(dimm);
    delay(5);
  }

}

I followed this diagram:

I connected the unpinned GND (Data In) and HE (Data In) to the other GND. I also tried not to connect "HD".

Power supply of the panel is a 5.1V DC 4A (20.4W).
Power supply of the NodeMCU is the USB connector plugged into the USB port of the computer for testing.

I assume it has something to do with the cabling or the NodeMCU because I also connected another matrix panel meanwhile in order to see if that's behaving the same way. And yes, it does.

phil2023 · January 22, 2023, 2:32am

...and because I wasn't able to make my first post with too many links here is the rest of my text:

NodeMCU is from Azdelivery Amica V2 ESP8266MOD 12-F (Nodemcu Lua Amica Module with ESP8266 12F at AZ-Delivery.de)
Panel is a Adafruit P3 64x32 (64x32 RGB LED Matrix - 3mm pitch : ID 2279 : $44.95 : Adafruit Industries, Unique & fun DIY electronics and kits)

phil2023 · January 22, 2023, 2:32am

I also read:
https://www.instructables.com/RGB-LED-Matrix-With-an-ESP8266/ (RGB LED Matrix With an ESP8266)

phil2023 · January 22, 2023, 2:33am

Your link is a white square rather than video

Very true!

Here it is again...

runaway_pancake · January 22, 2023, 2:42am

No difference. Maybe try vimeo.

PE - Just want to note "64 x 8" is 256, and each neopixel takes about 1mA quiescent (doing nothing), making that part of the project pulls around 250mA -- just sitting dark (then start adding LED On current).

xfpd · January 22, 2023, 4:23am

My Windows 11 thinks it is an audio file.

phil2023 · January 22, 2023, 8:17am

Sorry guys,
My Windows browser plays it well embedded. What about this one? Any better? If not, then I will try Vimeo as suggested.

b707 · January 22, 2023, 9:28am

Such matrices as those of the OP work as a dynamic indication, at each moment of time only two lines of 64 pixels are lit.
And yes, it's not neopixel

b707 · January 22, 2023, 9:37am

Yes, your video is visible now.
It is hardily can be called just flickering, in fact, the matrix does not work for you.
Can you post a photo of the back side of the matrix so that the inscriptions can be seen?
Have you tried using other libraries for RGB matrices, such as SmartMatrix , ESP32-HUB75-MatrixPanel-DMA or Protomatter? If you have a RP2040 type board, you can also try DMD_STM32 library

phil2023 · January 22, 2023, 10:27am

Can you post a photo of the back side of the matrix so that the inscriptions can be seen?

Here is the back side.
I will try the mentioned libraries!

Here is the currect panel I am testing with:

phil2023 · January 22, 2023, 10:28am

Same panel, zoomed in...

(sorry, I can only use one embedded photo per post)

phil2023 · January 22, 2023, 10:28am

..and this one is the first panel I was using and testing:

It behaved the same way.

phil2023 · January 22, 2023, 11:00am

Have you tried using other libraries for RGB matrices, such as [SmartMatrix] , [ESP32-HUB75-MatrixPanel-DMA] or [Protomatter]? If you have a RP2040 type board, you can also try [DMD_STM32] library

Having looked at these libraries it seems that they use either ESP32 (I have ESP8266) or a specific other board (like the Adafruit MatrixPortal M4).
That's why I tried the PxMatrix as this library refers to ESP8266.

b707 · January 22, 2023, 4:42pm

Could you inform what the names of the chips U1-U2, UG... and T1-T4 on your matrix?

phil2023 · January 22, 2023, 5:06pm

Could you inform what the names of the chips U1-U2, UG... and T1-T4 on your matrix?

My current testing panel (P3-2121-64x32-16S-D1.0):
"U" rows are: CHIPONE ICN2037BP B47271MA
"T" chips are: RUC7258D OWC20140

The other panel (P3-2121-64x32-16S-HL1.0) has:
"U": 6124D NCH591000
"T": RUC7258D OAD18871

TomGeorge · January 22, 2023, 5:20pm

Hi,
Where did you get the Fritzy picture in post #5?

Thanks.. Tom..

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