Add Mandelbrot example to DMA folder. It takes code from the 3D spinn…

examples/DMA test/Mandelbrot_DMA/Mandelbrot_DMA.ino/Mandelbrot_DMA.ino.ino

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+// Mandelbrot set generator
+// Based on the C# version at:http://csharphelper.com/blog/2014/07/draw-a-mandelbrot-set-fractal-in-c/
+// Tiling code adapted from SpriteRotatingCube.ino demo in this library
+#include <SPI.h>
+#include <TFT_eSPI.h>  // Hardware-specific library
+TFT_eSPI tft = TFT_eSPI();  // Invoke custom library
+
+
+// Mandelbrot calculation settings
+// 1. Define area to show
+double yMin = -1.25;
+double yMax = 1.2;
+double xMin = -2.5;
+double xMax = 1.58;
+// 2. Define max iterations per pixel
+#define MaxIterations 30
+// 3. Define max magnitude squared.
+const int MAX_MAG_SQUARED = 10;
+
+// Screen settings
+// 1. Set screen size to use
+#define SCREEN_WIDTH 800
+#define SCREEN_HEIGHT 480
+// 2. Set tile size
+#define TILEWIDTH  200
+#define TILEHEIGHT 120
+
+#define BACKLIGHT_PIN 5
+#define COLOR_DEPTH 16
+
+typedef struct rgb
+{
+  int r;
+  int g;
+  int b;
+} rgb;
+
+const int colourCount = 60;
+uint32_t colours[MaxIterations];
+
+// Sprite for drawing.
+TFT_eSprite sprite  = TFT_eSprite(&tft);
+// Pointer to start of sprite in RAM
+uint16_t* spritePointer;
+
+void setup()
+{
+  Serial.begin(115200); 
+  delay(2000);
+  randomSeed ( analogRead ( 0 ) );
+  configureScreen();
+  defineSprite();
+  createColourArray();
+
+  calculateMandelbrot();
+}
+
+void configureScreen()
+{
+  Serial.println("initialise screen");
+  pinMode(BACKLIGHT_PIN, OUTPUT);
+  digitalWrite(BACKLIGHT_PIN, HIGH);
+  tft.init();
+  tft.setRotation(1);
+  tft.fillScreen( TFT_BLACK);
+  tft.setTextSize(1);
+  tft.setTextColor(TFT_WHITE);
+  tft.setCursor(0, 0);
+  Serial.println("screen initialised\n");
+}
+
+void defineSprite()
+{
+  // Define sprite colour depth
+  sprite.setColorDepth(COLOR_DEPTH);
+  // Create the sprite
+  spritePointer = (uint16_t*)sprite.createSprite(TILEWIDTH, TILEHEIGHT);
+
+  // Define text datum and text colour for sprite
+  sprite.setTextColor(TFT_BLACK);
+  sprite.setTextDatum(MC_DATUM);
+}
+
+void loop()
+{
+  // put your main code here, to run repeatedly:
+}
+
+void createColourArray()
+{
+  int steps = MaxIterations/7;
+  int offset = 0;
+  rgb stages[7];
+  stages[0].r = 0; stages[0].g = 0; stages[0].b = 0;
+  stages[1].r = 0; stages[1].g = 0; stages[1].b = 255;
+  stages[2].r = 0; stages[2].g = 255; stages[2].b = 0;
+  stages[3].r = 0; stages[3].g = 0; stages[3].b = 0;
+  stages[4].r = 255; stages[4].g = 255; stages[4].b = 255;
+  stages[5].r = 0; stages[5].g = 0; stages[5].b = 0;
+  stages[6].r = 255; stages[6].g = 255; stages[6].b = 255;
+
+  for (int r = 0; r < 6; r++)
+  {
+    rgb startCol = stages[r];
+    rgb endCol = stages[r + 1];
+
+    double rDelta = (double)(endCol.r - startCol.r) / (double)steps;
+    double gDelta = (double)(endCol.g - startCol.g) / (double)steps;
+    double bDelta = (double)(endCol.b - startCol.b) / (double)steps;
+
+    double newRed = startCol.r;
+    double newGreen = startCol.g;
+    double newBlue = startCol.b;
+    for (int i = 0; i < steps; i++)
+    {
+      colours[offset] = tft.color565((int)newRed, (int)newGreen, (int)newBlue);
+      newRed += rDelta;
+      newGreen += gDelta;
+      newBlue += bDelta;
+      offset++;
+    }
+  }
+}
+
+void calculateMandelbrot()
+{
+  Serial.print("Calculate Mandelbrot set\n");
+  Serial.print("("); Serial.print(xMin); Serial.print(", "); Serial.print(yMin); Serial.print(") -> (");
+  Serial.print(xMax); Serial.print(", "); Serial.print(yMax); Serial.println(")");
+  double xOffset = xMin;
+  double yOffset = yMin;
+  double xTiles = (double)SCREEN_WIDTH / (double)TILEWIDTH;
+  double yTiles = (double)SCREEN_HEIGHT / (double)TILEHEIGHT;
+  double xTileRealWidth = (xMax - xMin) / xTiles;
+  double yTileRealHeight = (yMax - yMin) / yTiles;
+  Serial.printf("drawing set, based on sprites sized (%dx%d) in screen (%dx%d) - tiles (%fx%f) - tile set space (%fx%f) \n ",TILEWIDTH,TILEHEIGHT, SCREEN_WIDTH, SCREEN_HEIGHT,xTiles, yTiles,xTileRealWidth, yTileRealHeight);
+
+  int startTime = millis();
+  for(int x = 0; x < SCREEN_WIDTH; x+= TILEWIDTH)
+  {
+    for(int y = 0; y < SCREEN_HEIGHT; y+= TILEHEIGHT)
+    {
+      CalculateMandelbrotTile(xOffset, xOffset + xTileRealWidth, yOffset, yOffset + yTileRealHeight, x, y);
+      yOffset += yTileRealHeight;
+    }
+    xOffset += xTileRealWidth;
+    yOffset = yMin;
+  }
+  int endTime = millis();
+
+  Serial.print("Calculation complete in: "); Serial.print(endTime - startTime); Serial.println("ms");
+}
+
+void CalculateMandelbrotTile(double xStart, double xEnd, double yStart, double yEnd, int spritePositionX, int spritePositionY)
+{
+  double dReaC = (xEnd - xStart) / (TILEWIDTH - 1);
+  double dImaC = (yEnd - yStart) / (TILEHEIGHT - 1);
+  double xStep = (xEnd - xStart) / (double)TILEWIDTH;
+  double yStep = (yEnd - yStart) / (double)TILEHEIGHT;
+
+  double Zr = 0;
+  double Zim = 0;
+  double Z2r = 0;
+  double Z2im = 0;
+
+  double xPos = xStart;
+  double ReaC = xStart;
+  long startTime = millis();
+
+  for(int32_t x = 0; x < TILEWIDTH; x++)
+  {
+    double yPos = yStart;
+    double ImaC = yStart;
+    for (int32_t y = 0; y < TILEHEIGHT; y++)
+    {
+      double ReaZ = Zr;
+      double ImaZ = Zim;
+      double ReaZ2 = Z2r;
+      double ImaZ2 = Z2im;
+      int clr = 1;
+      while ((ReaZ2 + ImaZ2 < MAX_MAG_SQUARED) && (clr < MaxIterations))
+      {
+        // Calculate Z(clr).
+        ReaZ2 = ReaZ * ReaZ;
+        ImaZ2 = ImaZ * ImaZ;
+        ImaZ = 2 * ImaZ * ReaZ + ImaC;
+        ReaZ = ReaZ2 - ImaZ2 + ReaC;
+        clr++;
+      }
+
+      uint32_t colour =  colours[clr % MaxIterations];
+      // Set the pixel's value.
+      sprite.drawPixel(x, y,colour);
+      ImaC += dImaC;
+    }
+    ReaC += dReaC;
+  }
+  long duration = millis() - startTime;
+  Serial.printf("Calc a tile at position: (%d,%d) with data range (%f,%f) -> (%f,%f) duration %dms \n", spritePositionX, spritePositionY, xStart, yStart, xEnd, yEnd, duration);
+
+  #ifdef USE_DMA_TO_TFT
+  if (tft.dmaBusy()) prime_max++; // Increase processing load until just not busy
+    tft.pushImageDMA(spritePositionX, spritePositionY, TILEWIDTH, TILEHEIGHT,  spritePointer);
+  #else
+  sprite.pushSprite(spritePositionX, spritePositionY); // Blocking write (no DMA) 115fps 
+  #endif
+  //sprite.fillSprite(TFT_BLACK);
+}