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use. We also define the CS_PIN as required for the touchscreen to be GPIO 16.
There is no need to define the rest of the pins as that has been done for you in User_Setup.h which is part of the
TFT_eSPI library.
// touchscreen calibration values
#define X_MIN 256
#define X_MAX 3632
#define Y_MIN 274
#define Y_MAX 3579
These calibration values will vary from display to display. You can use the draw-corners example to find out the values
for each corner and change them for your displays. The values here are likely to be OK for initial testing but you will
get more accurate results by performing your own calibration.
pinMode( 33 , OUTPUT);
digitalWrite( 33 , HIGH);
These lines are critical as GPIO 33 is used to power on the back-light. The back-light is driven through a transistor to
avoid drawing too much current from the GPIO.
ts.begin();
ts.setCalibration(X_MIN, X_MAX, Y_MIN, Y_MAX);
tft.init();
These lines initialize and calibrate the touchscreen and display.
// Set the TFT and touch screen to landscape orientation
tft.setRotation( 1 );
ts.setRotation( 1 );
Rotation 0 and 2 are portrait and 1 and 3 are landscape. This example will work in any of the rotations so you can
change them and see the effect. Remember to keep them in sync or you will get strange effects.
tft.setTextSize( 1 );
tft.fillScreen(TFT_BLACK);
tft.setTextColor(TFT_GREEN);
This sets the default font-seize, sets the background to black and sets the current text color. Note that much better
smooth fonts are easily usable - take a look at the TFT_eSPI library documentation.
swatchWidth = ts.getWidth() / 10 ;
swatchHeight = 34 ;
This example dynamically determines the display width so that it works in any orientation.
tft.fillRect(i
*
swatchWidth, 0 , swatchWidth, swatchHeight, colors[i]);
This fills a rectangle with a color.
tft.setCursor(ts.getWidth() - swatchWidth
*
1.5 , 3 , 2 ); // x,y,font
tft.setTextColor(TFT_WHITE);
tft.print( "Clear" );
These lines position the cursor, set the text color and write some text at the cursor position.
68 Chapter 22. IoT-Bus Touch Draw Example