Monday, February 18, 2019

P3 64x32 HUB75E LED matrix panels with FM6126A Chip

I purchased a P3 (3mm LED spacing) 64 by 32 HUB75E Panel on eBay.  Needless to say it does not work with a "normal" HUB75 interface.  HUB75E adds a row select called "E" that ties to A4 to get the panel working.  That make 32 row selections possible.  Otherwise noise on that pin would cause garbage to come up on the display once in a while.

Here is a picture of the HUB75 connector from someone else on the Internet.  Note the "E" pin in the middle right of the pin listing.

So far I can only get it to turn all white or half white.  I am working on my own code since all the drivers out there are insanely complex!

 This picture shows the mod to connect E (Located between B and G2) to A4, using the lower yellow jumper wire.  The upper yellow jumper is for the clock to go to D8 or to D11 for use with the Mega.

This is the first video of it starting to work:

Here is a video of THREE 64x32 panels working with an Arduino UNO.

This video shows three panels with different text and background colors.

This is a picture of the display with some different color backgrounds.

The FM6126A Spec sheet tells how the chip is not just a normal shift register.  This was translated from the Chinese manual with google translate.  Basically the number of clock pulses while the LE (Latch Enable) is high tells the shift register what to do.  Three clock pulses are required to latch and display the data.  No clock pulses resets the display to blank.  That explains why most demo programs come up with a blank display.  Eleven or twelve clock pulses access the control registers.  Some people say you can set all the data for the control registers to high and that works.

Instruction         LE     Instruction Description
---------------        ---        ----------------------------
RESET_OEN      0-1     Soft reset signal
DATA_LATCH 3         latches 16 bit data to the output
--                       4~10    Reserved
WR_REG1        11       Write configuration register 1
WR_REG2        12       Write configuration register 2

Remark: The length of LE refers to the number of rising edges of CLK when LE is high. As shown in the figure below, the length of the first LE signal is 3, which is the "Data_Latch" command.

Here is two of the panels working with a Raspberry Pi after running

This is the Raspberry Pi VU meter demo program;

This is the back side of one of the LED panels;

My Arduino code is now compatable with the Adafruit demos!

Here is the Youtube Video:

Now some pictures of the demo's running, the first two are called "Plasma"

This is the "Test Shapes" demo:

// 128x32 Uno LED panel driver
// Fast Clock Mod
// 3/4/2019 by Bob Davis

// #define A   A0  // Port D assignments
// #define B   A1
// #define C   A2
// #define D   A3
// #define E   A4
// #define CLK 8 // Port B assignments 
// #define OE  9
// #define LAT 10

int C12[16] = {0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1};
int C13[16] = {0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0};

#define MaxLed 128
byte BGC1=0x04;  // Background
byte FGC1=0x1C;  // Foreground
byte BGC2=0x20;  // Background
byte FGC2=0xE0;  // Foreground

#define PIXEL_PORT PORTD  // Port the pixels are connected to
#define PIXEL_DDR  DDRD   // D2-D7
#define ROW_PORT   PORTC  // Port the rows are connected to
#define ROW_DDR    DDRC   // A0-A5
#define CLK_PORT   PORTB  // Port the Clock/LE/OE are connected to
#define CLK_DDR    DDRB   // D8-D10

char text1[]="ARDUINO UNO RUNS        ";
char text2[]="TWO 64X32 PANELS        ";

// This font from
byte font[][7] = {
0x00,0x00,0x00,0x00,0x00,0x00,0x00, // ascii 32
0x00,0x00,0xfa,0x00,0x00,0x00,0x00, // !
0x00,0xe0,0x00,0xe0,0x00,0x00,0x00, // "
0x28,0xfe,0x28,0xfe,0x28,0x00,0x00, // #
0x00,0x34,0xfe,0x58,0x00,0x00,0x00, // $
0xc4,0xc8,0x10,0x26,0x46,0x00,0x00, // %
0x6c,0x92,0xaa,0x44,0x0a,0x00,0x00, // &
0x00,0xa0,0xc0,0x00,0x00,0x00,0x00, // '
0x00,0x38,0x44,0x82,0x00,0x00,0x00, // (
0x00,0x82,0x44,0x38,0x00,0x00,0x00, // )
0x10,0x54,0x38,0x54,0x10,0x00,0x00, // *
0x10,0x10,0x7c,0x10,0x10,0x00,0x00, // +
0x00,0x0a,0x0c,0x00,0x00,0x00,0x00, // ,
0x10,0x10,0x10,0x10,0x10,0x00,0x00, // -
0x00,0x06,0x06,0x00,0x00,0x00,0x00, // .
0x04,0x08,0x10,0x20,0x40,0x00,0x00, // /
0x7c,0x8a,0x92,0xa2,0x7c,0x00,0x00, // 0
0x00,0x42,0xfe,0x02,0x00,0x00,0x00, // 1
0x42,0x86,0x8a,0x92,0x62,0x00,0x00, // 2
0x84,0x82,0xa2,0xd2,0x8c,0x00,0x00, // 3
0x18,0x28,0x48,0xfe,0x08,0x00,0x00, // 4
0xe4,0xa2,0xa2,0xa2,0x9c,0x00,0x00, // 5
0x3c,0x52,0x92,0x92,0x0c,0x00,0x00, // 6
0x80,0x8e,0x90,0xa0,0xc0,0x00,0x00, // 7
0x6c,0x92,0x92,0x92,0x6c,0x00,0x00, // 8
0x60,0x92,0x92,0x94,0x78,0x00,0x00, // 9
0x00,0x6c,0x6c,0x00,0x00,0x00,0x00, // :
0x00,0x6a,0x6c,0x00,0x00,0x00,0x00, // ;
0x00,0x10,0x28,0x44,0x82,0x00,0x00, // <
0x28,0x28,0x28,0x28,0x28,0x00,0x00, // =
0x82,0x44,0x28,0x10,0x00,0x00,0x00, // >
0x40,0x80,0x8a,0x90,0x60,0x00,0x00, // ?
0x4c,0x92,0x9e,0x82,0x7c,0x00,0x00, // @
0x7e,0x90,0x90,0x90,0x7e,0x00,0x00, // A
0xfe,0x92,0x92,0x92,0x6c,0x00,0x00, // B
0x7c,0x82,0x82,0x82,0x44,0x00,0x00, // C
0xfe,0x82,0x82,0x82,0x7c,0x00,0x00, // D
0xfe,0x92,0x92,0x92,0x82,0x00,0x00, // E
0xfe,0x90,0x90,0x80,0x80,0x00,0x00, // F
0x7c,0x82,0x82,0x8a,0x4c,0x00,0x00, // G
0xfe,0x10,0x10,0x10,0xfe,0x00,0x00, // H
0x00,0x82,0xfe,0x82,0x00,0x00,0x00, // I
0x04,0x02,0x82,0xfc,0x80,0x00,0x00, // J
0xfe,0x10,0x28,0x44,0x82,0x00,0x00, // K
0xfe,0x02,0x02,0x02,0x02,0x00,0x00, // L
0xfe,0x40,0x20,0x40,0xfe,0x00,0x00, // M
0xfe,0x20,0x10,0x08,0xfe,0x00,0x00, // N
0x7c,0x82,0x82,0x82,0x7c,0x00,0x00, // O
0xfe,0x90,0x90,0x90,0x60,0x00,0x00, // P
0x7c,0x82,0x8a,0x84,0x7a,0x00,0x00, // Q
0xfe,0x90,0x98,0x94,0x62,0x00,0x00, // R
0x62,0x92,0x92,0x92,0x8c,0x00,0x00, // S
0x80,0x80,0xfe,0x80,0x80,0x00,0x00, // T
0xfc,0x02,0x02,0x02,0xfc,0x00,0x00, // U
0xf8,0x04,0x02,0x04,0xf8,0x00,0x00, // V
0xfe,0x04,0x18,0x04,0xfe,0x00,0x00, // W
0xc6,0x28,0x10,0x28,0xc6,0x00,0x00, // X
0xc0,0x20,0x1e,0x20,0xc0,0x00,0x00, // Y
0x86,0x8a,0x92,0xa2,0xc2,0x00,0x00,  // Z

void setup() {
  PIXEL_DDR = 0xFF;  // Set all pixel pins to output
  ROW_DDR = 0xFF;    // Set all row pins to output
  CLK_DDR = 0xFF;    // Set all CLK/LE/OE pins to output

  // Send Data to control register 11
  for (int l=0; l<MaxLed; l++){
    int y=l%16;
    PORTD = 0x00;
    if (C12[y]==1) PORTD=0xFC;
      if (l>MaxLed-12){ PORTB=7; PORTB=6; }
      else{ PORTB=1; PORTB=0; }
  // Send Data to control register 12
  for (int l=0; l<MaxLed; l++){
    int y=l%16;
    PORTD = 0x00;
    if (C13[y]==1) PORTD=0xFC;
      if (l>MaxLed-13){ PORTB=7; PORTB=6; }
      else{ PORTB=1; PORTB=0; }

void loop() {
  for (int c=0; c<600; c++){
    if (c > 000){BGC1=0x04; BGC2=0x20; FGC1=0x1C; FGC2=0xE0;}
    if (c > 200){BGC1=0x08; BGC2=0x40; FGC1=0x1C; FGC2=0xE0;}
    if (c > 400){BGC1=0x10; BGC2=0x80; FGC1=0x1C; FGC2=0xE0;}
    // Select the Row
    for (int r=0; r<16; r++){
      for (int l=0; l<MaxLed; l++){
        int y=l%8; // remainder after division
        int pd1 = BGC1;
        int pd2 = BGC2;
        if (y < 6){
          if ((font[text1[l/8]-32][y] >> 8-r/2) & 0x01==1) pd1=FGC1;
          if ((font[text2[l/8]-32][y] >> 8-r/2) & 0x01==1) pd2=FGC2;
        if (l<MaxLed-3) {PORTB=1; PORTB=0;}
        else {PORTB=7; PORTB=6;}
      PORTC=r;  // Update row


SpydaSammage said...

This is great stuff Bob! Any chance we can see the sketches for the other demo programs as well?

robiv8 said...

If I understand you correctly, you can use the P3 64x32 panel with the FM6126A chip.
I have the Identical Panel as seen in your picture. (Https://
I have been trying for days with an ESP8266 and the MorphingClock Sketch.
Would you show me (as text or image) how this is wired.
Thank you and nice Easter

PS.: I have the following devices to choose from:
ESP8266, ESP32, Arduino UNO Nano and a WeMos ESP14,

Unknown said...

Thanks, your code works with the new P3 panels having FM6126A chips. I am trying to port this library to STM32F103C8T6 (bluepill). Could you please let me know where I can find the datasheet for FM6126A?


Unknown said...

I'm getting error
error: 'PORTD' was not declared in this scope
any idea ?

n13ldo said...

Compiling in Arduino results in 'error: 'DDRD' was not declared in this scope' and similar for 'DDRC', 'DDRB', 'PORTB', 'PORTD', 'PORTC'

Anonymous said...

Hi Bob

Is the assumption the code shown above for the UNO is to be used with the Adafruit Matrix Shield?

Thanks for any help as you may imagine these panels ar enot the easiest to get working.

I have had success using a Mega with the DF_Robot library.

Still trying to get my ESP32 working.


GalaxyMan (Github)

Anonymous said...

Goto the ESP32 working, so all is ok with the world now.


Unknown said...

Hi, I have similar problem with different chip. By mistake I have ordered wrong panels and cannot configure them. It woould be very sad to unuse them as where is a lot of interesting ideas for diy projects.

I was trying to use Px Matrix library with ESP32 and wrote down my issue here

Led driver chip is MBI 5120

Would appreciate your help as I am looking to solve this problem desperately!

Bob Davis said...

The ESP32 does not have 8 bit I/O ports. I am curious as to how GalaxyMan got it working?

To: Unknown with the MBI 5120 chips, it looks like you almost have it working.

Ndembo255 said...

May how can I use this code to Control 64x64 P4 (256cm x 256cm) with HUB75E with arduino Uno?

Bob Davis said...

The 64x64 array would require another bit to select upper or lower 32 halfs. Send me one and I will figure it out?

away said...

64x32 P2.5 HUB75E(have E) with chip "FM6126A" - do not working with ESP32 + SmartMatrix library. Work with Raspberry Pi only.

Bob Davis said...

I have been thinking about porting my code to the ESP32....

Unknown said...

hello, please how to build a 64*64 LEDS matrix

Unknown said...

Hi Bob, great job!
Did you find any method to set the brightness of the panel using the OE pin (PWM)?

Anonymous said...

Hey Bob,

great Job. I try to get it working with an ESP8266 NodeMCU. Unfortunately, the led brightness does not work. Only the LEDs on the left bottom have full brightness. The other ones not. The driver chip of the LED Matrix is FM6126B. Do you have a workaround for this issue?

Thanks in advance.

Bob Davis said...

I have never tried the code with an ESP8266, so I do not know what went wrong. -Bob

Unknown said...

Hello Bob,

great job. I just started to work with these panels.

Just got a 64x64 P3 Panel, it has only A,B,C and E pins. Do you have any idea how this can work only with 4 selection pins ?

Hope you have an idea or hint about it.

Bob Davis said...

I have never played with a 64x64 panel. I do not know why htye skipped the D pin. Sorry.

Unknown said...

thanks Bob for fast answer.

After measuring pin continuity, I realized one GND pin is actually D pin ( wrong label on panel)

Was able to run today morning some demos using

with following modifications:

change number of rows and columns to 64
number of panels set to 2
connect wrong labeled pin to E control pin in esp32 board
assign number to E pin on board configuration

Actually my target board is an rpi. At least now happy to know the panel itself is ok. Still need to find the way to control in with the rpi library