Smart LED Matrix for Particle Photon

// Simple LED Matrix Display with Blynk and Weather Integration 
// Uses 4x MAX7219 Dot Matrix Modules to display messages
// Make sure you add these two libraries using the Particle IDE

#include <ledmatrix-max7219-max7221.h>
#include <blynk.h>

char auth[] = "1234"; // Put your blynk token here

LEDMatrix *led;

int bitmapWidth = 8;   // 8 is default
int webcount = 60001;   // timer to run the weather webhook every 60 seconds

String text = "Hello World";   // default string for display
String text2 = "No Texts";  //  default string for Blynk texts
String text3 = "Getting Weather"; // default string for weather

int mode = 0;

int textLength = text.length();

// default position of the text is outside and then scrolls left
int textX = bitmapWidth;
int fontWidth = 5, space = 1;

void drawText(String s, int x)
{
  int y = 0;
  for(int i = 0; i < s.length(); i++) {
    // Adafruit_GFX method
    led->drawChar(x + i*(fontWidth+space), y, s[i], true, false, 1);
  }
}


void setup() {
  Blynk.begin(auth);   // setup Blynk 
  // setup pins and library
  // 1 display per row, 1 display per column
  // optional pin settings - default: CLK = A0, CS = A1, D_OUT = A2
  // (pin settings is independent on HW SPI)
  led = new LEDMatrix(4, 1, D1, D2, D3); // my pins vary from the default
  // > add every matrix in the order in which they have been connected <
  // the first matrix in a row, the first matrix in a column
  // vertical orientation (-90°) and no mirroring - last three args optional
  // the Wangdd22 Matrix has 4 matrix elements, arranged side-by-side
  led->addMatrix(3, 0, 0, false, false);
  led->addMatrix(2, 0, 0, false, false);
  led->addMatrix(1, 0, 0, false, false);
  led->addMatrix(0, 0, 0, false, false);
  
  Particle.subscribe("hook-response/get_weather", gotWeatherData, MY_DEVICES);   // see particle.io tutorial on weather webhooks
}

// In the Blynk app, I used the Termianl widget on virtual pin V1 to send text messages for display.  
BLYNK_WRITE(V1) {
   String cmd = param[0].asStr();
   text2 = cmd;
}

// In the Blynk app, I used V2 as a button to toggle mode between weather and texts.
BLYNK_WRITE(V2){
    mode = param.asInt();
}

// This collects data from my get_weather webhook, METAR data in my example.  See the photon tutorial on webhooks to get other data.  https://docs.particle.io/tutorials/integrations/webhooks/

void gotWeatherData(const char *name, const char *data) {
    text3 = String(data);
}

void loop() {
    Blynk.run();   

    if (webcount > 60000) {    // fetch data via the webhook only once a minute
        Particle.publish("get_weather"); 
        webcount = 0;
    }

// pick which text string will be displayed
    if (mode == 0) {
        text = text3;
        textLength = text.length();
    }    
    
    if (mode == 1) {
        text = text2;
        textLength = text.length();
    }
    
    webcount = webcount + 1;
    
  if(led != NULL) {
    drawText(text, textX--);
    // text animation is ending when the whole text is outside the bitmap
    if(textX < textLength*(fontWidth+space)*(-1)) {
      // set default text position
      textX = bitmapWidth;
      // show heart
      led->flush();
      delay(333);   // 1000 is default
      // turn all pixels off (takes effect after led->flush())
      led->fillScreen(false);
    }
    // draw text
    led->flush();
    delay(125);   // 250 is default 
  }
  // animations end
  else if (led != NULL) {
    // shutdown all displays
    led->shutdown(true);
    // free memory
    delete led;
    led = NULL;
  }
}