unable to use RGB matrix and the serial monitor at once

Using Arduino Programming Questions
#1

Hello,

Recently I bought the following matrix:

I own an Arduino Uno for those who are interested.

I got the 32x32 variant and I am very happy with it. I managed to connect all the wires correctly and get the examples of the library working.

The problem I am facing right now is I can’t get it to work properly for a personal project of mine. Somehow I am unable to use the serial functions and the matrix library functions in one project.

Currently my project looks like this:

Arduino is connected like this:

800×600 20.2 KB

And my code looks like this:

#include <gamma.h>
#include <RGBmatrixPanel.h>
#include <Adafruit_GFX.h>
#include <gfxfont.h>

#define CLK 8
#define OE  9
#define LAT 10
#define A   A0
#define B   A1
#define C   A2
#define D   A3

RGBmatrixPanel matrix(A, B, C, D, CLK, LAT, OE, false);

String incomingCommand = "";

void setup()
{
  Serial.begin(9600);

  matrix.begin();

  matrix.fillRect(0, 0, 32, 32, matrix.Color333(0, 0, 0));
}

void loop()
{
  if (Serial.available() > 0)
  {
    int incomingByte = Serial.read();
    char receivedChar = (char) incomingByte;

    incomingCommand += receivedChar;
  }

  if (incomingCommand.indexOf('#') > - 1 && incomingCommand.indexOf('%') > - 1)
  {
    String rawCommand = incomingCommand.substring(incomingCommand.indexOf('#'), incomingCommand.indexOf('%') + 1);

    rawCommand = rawCommand.substring(1, rawCommand.length() - 1);

    Serial.print("Following command received: ");
    Serial.println(rawCommand);

    if (rawCommand == "turnledon")
    {
      matrix.drawPixel(0, 0, matrix.Color333(7, 7, 7));
    }

    incomingCommand = "";
    rawCommand = "";
  }
}

The idea is that a command gets send from the serial monitor. Based on the command one led on the matrix will turn on. An example of a future command will looke similair to this: “#drawPixel_X1_Y2%”, hence the part that checks on “#” and “&”.

The problem that I am facing is that the functionality of the serial monitor isn’t working with line 14 and 48 of the code. As soon as I remove those lines the serial monitor works perfectly and I can receive and write to the serial monitor. I have no idea what is causing this.

I was wondering if someone ever faced with a similair problem or just knows what I am doing wrong right now.

Thank you in advance!

#2

Nobody encountered this issue?

The funny thing I just found out if I remove D from this line: RGBmatrixPanel matrix(A, B, C, D, CLK, LAT, OE, false);

I get it working but the matrix will only light up half of the pixels.

#3

HI, I’m facing exactly the same problem, were you able to find the fix?

Many thanks in advance for any help.

#4

These panels are normally run by very fast processors or FPGAs, not a 16 MHz Arduino. To achieve reasonable performance in this limited environment, the library is optimized by tying specific signals to specific Arduino pins and on a Uno they use PORT manipulation on full port and as you can see in the extract of the library on a UNO this is PORTD which encompasses PINs 0 to 7 so RX and TX

// A full PORT register is required for the data lines, though only the
// top 6 output bits are used.  For performance reasons, the port # cannot
// be changed via library calls, only by changing constants in the library.
// For similar reasons, the clock pin is only semi-configurable...it can
// be specified as any pin within a specific PORT register stated below.

#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
 // Arduino Mega is now tested and confirmed, with the following caveats:
 // Because digital pins 2-7 don't map to a contiguous port register,
 // the Mega requires connecting the matrix data lines to different pins.
 // Digital pins 24-29 are used for the data interface, and 22 & 23 are
 // unavailable for other outputs because the software needs to write to
 // the full PORTA register for speed.  Clock may be any pin on PORTB --
 // on the Mega, this CAN'T be pins 8 or 9 (these are on PORTH), thus the
 // wiring will need to be slightly different than the tutorial's
 // explanation on the Uno, etc.  Pins 10-13 are all fair game for the
 // clock, as are pins 50-53.
 #define DATAPORT PORTA
 #define DATADIR  DDRA
 #define SCLKPORT PORTB
#elif defined(__AVR_ATmega32U4__)
 // Arduino Leonardo: this is vestigial code an unlikely to ever be
 // finished -- DO NOT USE!!!  Unlike the Uno, digital pins 2-7 do NOT
 // map to a contiguous port register, dashing our hopes for compatible
 // wiring.  Making this work would require significant changes both to
 // the bit-shifting code in the library, and how this board is wired to
 // the LED matrix.  Bummer.
 #define DATAPORT PORTD
 #define DATADIR  DDRD
 #define SCLKPORT PORTB
#else
 // Ports for "standard" boards (Arduino Uno, Duemilanove, etc.)
 #define DATAPORT PORTD
 #define DATADIR  DDRD
 #define SCLKPORT PORTB
#endif

A few control lines can be reconfigured, but others are very specific.

So long story short if you want to keep a serial line, then get à MEGA.

Note that there are time sensitive operations so serial interrupts or blocking calls can mess up your display.

#5