/*
  An example showing 'ring' analogue meter on a TFT
  colour screen
 
  Needs Fonts 2, 4 and 7 (also Font 6 if using a large size meter)
  */
 
 // Meter colour schemes
 #define RED2RED 0
 #define GREEN2GREEN 1
 #define BLUE2BLUE 2
 #define BLUE2RED 3
 #define GREEN2RED 4
 #define RED2GREEN 5
 
 #define TFT_GREY 0x2104 // Dark grey 16 bit colour
 
 #include "Alert.h" // Out of range alert icon
 
 #include <TFT_eSPI.h> // Hardware-specific library
 #include <SPI.h>
 
 TFT_eSPI tft = TFT_eSPI(); // Invoke custom library with default width and height
 
 uint32_t runTime = -99999;       // time for next update
 
 int reading = 0; // Value to be displayed
 int d = 0; // Variable used for the sinewave test waveform
 bool range_error = 0;
 int8_t ramp = 1;
 
 void setup(void) {
   tft.begin();
   //Serial.begin(9600);
   tft.setRotation(1);
 
   tft.fillScreen(TFT_BLACK);
 }
 
 
 void loop() {
   if (millis() - runTime >= 0L) { // Execute every TBD ms
     runTime = millis();
 
     // Test with a slowly changing value from a Sine function
     //d += 4; if (d >= 360) d = 0;
 
     // Set the the position, gap between meters, and inner radius of the meters
     int xpos = 0, ypos = 5, gap = 4, radius = 52;
 
     // Draw meter and get back x position of next meter
 
     // Test with Sine wave function, normally reading will be from a sensor
     //reading = 250 + 250 * sineWave(d+0);
     //xpos = gap + ringMeter(reading, 0, 500, xpos, ypos, radius, "mA", GREEN2RED); // Draw analogue meter
 
     //reading = 20 + 30 * sineWave(d+60);
     //xpos = gap + ringMeter(reading, -10, 50, xpos, ypos, radius, "degC", BLUE2RED); // Draw analogue meter
 
     //reading = 50 + 50 * sineWave(d + 120);
     //ringMeter(reading, 0, 100, xpos, ypos, radius, "%RH", BLUE2BLUE); // Draw analogue meter
 
 
     // Draw two more larger meters
     //xpos = 20, ypos = 115, gap = 24, radius = 64;
 
     //reading = 1000 + 150 * sineWave(d + 90);
     //xpos = gap + ringMeter(reading, 850, 1150, xpos, ypos, radius, "mb", BLUE2RED); // Draw analogue meter
 
     //reading = 15 + 15 * sineWave(d + 150);
     //xpos = gap + ringMeter(reading, 0, 30, xpos, ypos, radius, "Volts", GREEN2GREEN); // Draw analogue meter
 
     // Draw a large meter
     xpos = 480/2 - 160, ypos = 0, gap = 15, radius = 170;
     reading +=(ramp);
     if (reading>98) ramp = -1;
     if (reading<0) ramp = 1;
     // Comment out above meters, then uncomment the next line to show large meter
     ringMeter(reading,0,100, xpos,ypos,radius," Watts",GREEN2RED); // Draw analogue meter
     if (reading<0) delay(1000);
   }
 }
 
 // #########################################################################
 //  Draw the meter on the screen, returns x coord of righthand side
 // #########################################################################
 int ringMeter(int value, int vmin, int vmax, int x, int y, int r, const char *units, byte scheme)
 {
   // Minimum value of r is about 52 before value text intrudes on ring
   // drawing the text first is an option
   
   x += r; y += r;   // Calculate coords of centre of ring
 
   int w = r / 3;    // Width of outer ring is 1/4 of radius
   
   int angle = 150;  // Half the sweep angle of meter (300 degrees)
 
   int v = map(value, vmin, vmax, -angle, angle); // Map the value to an angle v
 
   byte seg = 3; // Segments are 3 degrees wide = 100 segments for 300 degrees
   byte inc = 6; // Draw segments every 3 degrees, increase to 6 for segmented ring
 
   // Variable to save "value" text colour from scheme and set default
   int colour = TFT_BLUE;
  
   // Draw colour blocks every inc degrees
   for (int i = -angle+inc/2; i < angle-inc/2; i += inc) {
     // Calculate pair of coordinates for segment start
     float sx = cos((i - 90) * 0.0174532925);
     float sy = sin((i - 90) * 0.0174532925);
     uint16_t x0 = sx * (r - w) + x;
     uint16_t y0 = sy * (r - w) + y;
     uint16_t x1 = sx * r + x;
     uint16_t y1 = sy * r + y;
 
     // Calculate pair of coordinates for segment end
     float sx2 = cos((i + seg - 90) * 0.0174532925);
     float sy2 = sin((i + seg - 90) * 0.0174532925);
     int x2 = sx2 * (r - w) + x;
     int y2 = sy2 * (r - w) + y;
     int x3 = sx2 * r + x;
     int y3 = sy2 * r + y;
 
     if (i < v) { // Fill in coloured segments with 2 triangles
       switch (scheme) {
         case 0: colour = TFT_RED; break; // Fixed colour
         case 1: colour = TFT_GREEN; break; // Fixed colour
         case 2: colour = TFT_BLUE; break; // Fixed colour
         case 3: colour = rainbow(map(i, -angle, angle, 0, 127)); break; // Full spectrum blue to red
         case 4: colour = rainbow(map(i, -angle, angle, 70, 127)); break; // Green to red (high temperature etc)
         case 5: colour = rainbow(map(i, -angle, angle, 127, 63)); break; // Red to green (low battery etc)
         default: colour = TFT_BLUE; break; // Fixed colour
       }
       tft.fillTriangle(x0, y0, x1, y1, x2, y2, colour);
       tft.fillTriangle(x1, y1, x2, y2, x3, y3, colour);
       //text_colour = colour; // Save the last colour drawn
     }
     else // Fill in blank segments
     {
       tft.fillTriangle(x0, y0, x1, y1, x2, y2, TFT_GREY);
       tft.fillTriangle(x1, y1, x2, y2, x3, y3, TFT_GREY);
     }
   }
   // Convert value to a string
   char buf[10];
   byte len = 3; if (value > 999) len = 5;
   dtostrf(value, len, 0, buf);
   buf[len] = ' '; buf[len+1] = 0; // Add blanking space and terminator, helps to centre text too!
   // Set the text colour to default
   tft.setTextSize(1);
 
   if (value<vmin || value>vmax) {
     drawAlert(x,y+90,50,1);
   }
   else {
     drawAlert(x,y+90,50,0);
   }
 
   tft.setTextColor(TFT_WHITE, TFT_BLACK);
   // Uncomment next line to set the text colour to the last segment value!
   tft.setTextColor(colour, TFT_BLACK);
   tft.setTextDatum(MC_DATUM);
   // Print value, if the meter is large then use big font 8, othewise use 4
   if (r > 84) {
     tft.setTextPadding(55*3); // Allow for 3 digits each 55 pixels wide
     tft.drawString(buf, x, y, 8); // Value in middle
   }
   else {
     tft.setTextPadding(3 * 14); // Allow for 3 digits each 14 pixels wide
     tft.drawString(buf, x, y, 4); // Value in middle
   }
   tft.setTextSize(1);
   tft.setTextPadding(0);
   // Print units, if the meter is large then use big font 4, othewise use 2
   tft.setTextColor(TFT_WHITE, TFT_BLACK);
   if (r > 84) tft.drawString(units, x, y + 60, 4); // Units display
   else tft.drawString(units, x, y + 15, 2); // Units display
 
   // Calculate and return right hand side x coordinate
   return x + r;
 }
 
 void drawAlert(int x, int y , int side, bool draw)
 {
   if (draw && !range_error) {
     drawIcon(alert, x - alertWidth/2, y - alertHeight/2, alertWidth, alertHeight);
     range_error = 1;
   }
   else if (!draw) {
     tft.fillRect(x - alertWidth/2, y - alertHeight/2, alertWidth, alertHeight, TFT_BLACK);
     range_error = 0;
   }
 }
 
 // #########################################################################
 // Return a 16 bit rainbow colour
 // #########################################################################
 unsigned int rainbow(byte value)
 {
   // Value is expected to be in range 0-127
   // The value is converted to a spectrum colour from 0 = blue through to 127 = red
 
   byte red = 0; // Red is the top 5 bits of a 16 bit colour value
   byte green = 0;// Green is the middle 6 bits
   byte blue = 0; // Blue is the bottom 5 bits
 
   byte quadrant = value / 32;
 
   if (quadrant == 0) {
     blue = 31;
     green = 2 * (value % 32);
     red = 0;
   }
   if (quadrant == 1) {
     blue = 31 - (value % 32);
     green = 63;
     red = 0;
   }
   if (quadrant == 2) {
     blue = 0;
     green = 63;
     red = value % 32;
   }
   if (quadrant == 3) {
     blue = 0;
     green = 63 - 2 * (value % 32);
     red = 31;
   }
   return (red << 11) + (green << 5) + blue;
 }
 
 // #########################################################################
 // Return a value in range -1 to +1 for a given phase angle in degrees
 // #########################################################################
 float sineWave(int phase) {
   return sin(phase * 0.0174532925);
 }
 
 
 //====================================================================================
 // This is the function to draw the icon stored as an array in program memory (FLASH)
 //====================================================================================
 
 // To speed up rendering we use a 64 pixel buffer
 #define BUFF_SIZE 64
 
 // Draw array "icon" of defined width and height at coordinate x,y
 // Maximum icon size is 255x255 pixels to avoid integer overflow
 
 void drawIcon(const unsigned short* icon, int16_t x, int16_t y, int8_t width, int8_t height) {
 
   uint16_t  pix_buffer[BUFF_SIZE];   // Pixel buffer (16 bits per pixel)
 
   tft.startWrite();
 
   // Set up a window the right size to stream pixels into
   tft.setAddrWindow(x, y, width, height);
 
   // Work out the number whole buffers to send
   uint16_t nb = ((uint16_t)height * width) / BUFF_SIZE;
 
   // Fill and send "nb" buffers to TFT
   for (int i = 0; i < nb; i++) {
     for (int j = 0; j < BUFF_SIZE; j++) {
       pix_buffer[j] = pgm_read_word(&icon[i * BUFF_SIZE + j]);
     }
     tft.pushColors(pix_buffer, BUFF_SIZE);
   }
 
   // Work out number of pixels not yet sent
   uint16_t np = ((uint16_t)height * width) % BUFF_SIZE;
 
   // Send any partial buffer left over
   if (np) {
     for (int i = 0; i < np; i++) pix_buffer[i] = pgm_read_word(&icon[nb * BUFF_SIZE + i]);
     tft.pushColors(pix_buffer, np);
   }
 
   tft.endWrite();
 }
 

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