ILI9341_t3 - "touchpaint" example not working - found possible fix

[limmers2015]

Description

When attempting to use the "touchpaint" example sketch included in the ILI9341_t3 library, the touchscreen does not function, and locks up the whole SPI bus.

Steps To Reproduce Problem

• Load the example code from the aforementioned example sketch, and delete the if-while lockout loop in setup.
  Connect an ILI9341 display identical to the one PJRC sells (I purchased mine directly from pjrc.com) in the manner prescribed on pjrc.com.
  Flash the sketch.

Hardware & Software

Board: Teensy 4.1 (w/PSRAM chip)
Shields / modules used: "Color 320x240 TFT Touchscreen, ILI9341 Controller Chip"
Arduino IDE version: 1.8.13
Teensyduino version: 1.5.3
Operating system & version: MacOS High Sierra (10.13.6)
Other software or hardware: 10k pullup resistor on reset, breadboard, wires, 2x220 resistor in parallel for backlight

Arduino Sketch

/***************************************************
  This is our touchscreen painting example for the Adafruit ILI9341 Shield
  ----> http://www.adafruit.com/products/1651

  Check out the links above for our tutorials and wiring diagrams
  These displays use SPI to communicate, 4 or 5 pins are required to
  interface (RST is optional)
  Adafruit invests time and resources providing this open source code,
  please support Adafruit and open-source hardware by purchasing
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.
  MIT license, all text above must be included in any redistribution
 ****************************************************/


#include <SPI.h>
#include <Wire.h>      // this is needed even tho we aren't using it
#include <ILI9341_t3.h>
#include <Adafruit_STMPE610.h>

// This is calibration data for the raw touch data to the screen coordinates
#define TS_MINX 150
#define TS_MINY 130
#define TS_MAXX 3800
#define TS_MAXY 4000

// The STMPE610 uses hardware SPI on the shield, and #8
#define STMPE_CS 8
Adafruit_STMPE610 ts = Adafruit_STMPE610(STMPE_CS);

// The display also uses hardware SPI, plus #9 & #10
#define TFT_CS 10
#define TFT_DC  9
ILI9341_t3 tft = ILI9341_t3(TFT_CS, TFT_DC);

// Size of the color selection boxes and the paintbrush size
#define BOXSIZE 40
#define PENRADIUS 3
int oldcolor, currentcolor;

void setup(void) {
 // while (!Serial);     // used for leonardo debugging
 
  Serial.begin(9600);
  Serial.println(F("Touch Paint!"));
  
  tft.begin();

  if (!ts.begin()) {
    Serial.println("Couldn't start touchscreen controller");
    while (1);
  }
  Serial.println("Touchscreen started");
  
  tft.fillScreen(ILI9341_BLACK);
  
  // make the color selection boxes
  tft.fillRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_RED);
  tft.fillRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, ILI9341_YELLOW);
  tft.fillRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, ILI9341_GREEN);
  tft.fillRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, ILI9341_CYAN);
  tft.fillRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, ILI9341_BLUE);
  tft.fillRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, ILI9341_MAGENTA);
 
  // select the current color 'red'
  tft.drawRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
  currentcolor = ILI9341_RED;
}


void loop()
{
  // See if there's any  touch data for us
  if (ts.bufferEmpty()) {
    return;
  }
  /*
  // You can also wait for a touch
  if (! ts.touched()) {
    return;
  }
  */

  // Retrieve a point  
  TS_Point p = ts.getPoint();
  
 /*
  Serial.print("X = "); Serial.print(p.x);
  Serial.print("\tY = "); Serial.print(p.y);
  Serial.print("\tPressure = "); Serial.println(p.z);  
 */
 
  // Scale from ~0->4000 to tft.width using the calibration #'s
  p.x = map(p.x, TS_MINX, TS_MAXX, 0, tft.width());
  p.y = map(p.y, TS_MINY, TS_MAXY, 0, tft.height());

  /*
  Serial.print("("); Serial.print(p.x);
  Serial.print(", "); Serial.print(p.y);
  Serial.println(")");
  */

  if (p.y < BOXSIZE) {
     oldcolor = currentcolor;

     if (p.x < BOXSIZE) { 
       currentcolor = ILI9341_RED; 
       tft.drawRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     } else if (p.x < BOXSIZE*2) {
       currentcolor = ILI9341_YELLOW;
       tft.drawRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     } else if (p.x < BOXSIZE*3) {
       currentcolor = ILI9341_GREEN;
       tft.drawRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     } else if (p.x < BOXSIZE*4) {
       currentcolor = ILI9341_CYAN;
       tft.drawRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     } else if (p.x < BOXSIZE*5) {
       currentcolor = ILI9341_BLUE;
       tft.drawRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     } else if (p.x < BOXSIZE*6) {
       currentcolor = ILI9341_MAGENTA;
       tft.drawRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     }

     if (oldcolor != currentcolor) {
        if (oldcolor == ILI9341_RED) 
          tft.fillRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_RED);
        if (oldcolor == ILI9341_YELLOW) 
          tft.fillRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, ILI9341_YELLOW);
        if (oldcolor == ILI9341_GREEN) 
          tft.fillRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, ILI9341_GREEN);
        if (oldcolor == ILI9341_CYAN) 
          tft.fillRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, ILI9341_CYAN);
        if (oldcolor == ILI9341_BLUE) 
          tft.fillRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, ILI9341_BLUE);
        if (oldcolor == ILI9341_MAGENTA) 
          tft.fillRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, ILI9341_MAGENTA);
     }
  }
  if (((p.y-PENRADIUS) > BOXSIZE) && ((p.y+PENRADIUS) < tft.height())) {
    tft.fillCircle(p.x, p.y, PENRADIUS, currentcolor);
  }
}

Errors or Incorrect Output

The touchscreen does not function when its data is connected, and locks up the normal screen as well. When the touchscreen's data is disconnected, the normal screen functions properly, on the same code.

[limmers2015]

I have found a work-around (I was previously convinced that I had a bad display). Here is my updated code that seems to work properly with everything else the same (albeit with very poor touchscreen accuracy).

  This is our touchscreen painting example for the Adafruit ILI9341 Shield
  ----> http://www.adafruit.com/products/1651

  Check out the links above for our tutorials and wiring diagrams
  These displays use SPI to communicate, 4 or 5 pins are required to
  interface (RST is optional)
  Adafruit invests time and resources providing this open source code,
  please support Adafruit and open-source hardware by purchasing
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.
  MIT license, all text above must be included in any redistribution
 ****************************************************/


#include <SPI.h>
#include <Wire.h>      // this is needed even tho we aren't using it
#include <ILI9341_t3.h>
#include <XPT2046_Touchscreen.h>

// This is calibration data for the raw touch data to the screen coordinates
#define TS_MINX 150
#define TS_MINY 130
#define TS_MAXX 3800
#define TS_MAXY 4000

// The STMPE610 uses hardware SPI on the shield, and #8
#define STMPE_CS 8
#define TIRQ_PIN 2
XPT2046_Touchscreen ts(STMPE_CS,TIRQ_PIN);

// The display also uses hardware SPI, plus #9 & #10
#define TFT_CS 10
#define TFT_DC  9
ILI9341_t3 tft = ILI9341_t3(TFT_CS, TFT_DC);

// Size of the color selection boxes and the paintbrush size
#define BOXSIZE 40
#define PENRADIUS 3
int oldcolor, currentcolor;

void setup() {
 // while (!Serial);     // used for leonardo debugging
  delay(1000);
  Serial.begin(9600);
  Serial.println(F("Touch Paint!"));
  
  tft.begin();
  ts.begin();
  ts.setRotation(2);

  tft.fillScreen(ILI9341_BLACK);
  
  // make the color selection boxes
  tft.fillRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_RED);
  tft.fillRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, ILI9341_YELLOW);
  tft.fillRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, ILI9341_GREEN);
  tft.fillRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, ILI9341_CYAN);
  tft.fillRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, ILI9341_BLUE);
  tft.fillRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, ILI9341_MAGENTA);
 
  // select the current color 'red'
  tft.drawRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
  currentcolor = ILI9341_RED;
}


void loop()
{
  // See if there's any touch data for us
  if (ts.bufferEmpty()) {
    return;
  }
  /*
  // You can also wait for a touch
  if (! ts.touched()) {
    return;
  }
  */

  // Retrieve a point  
  TS_Point p = ts.getPoint();
  
 /*
  Serial.print("X = "); Serial.print(p.x);
  Serial.print("\tY = "); Serial.print(p.y);
  Serial.print("\tPressure = "); Serial.println(p.z);  
 */
 
  // Scale from ~0->4000 to tft.width using the calibration #'s
  p.x = map(p.x, TS_MINX, TS_MAXX, 0, tft.width());
  p.y = map(p.y, TS_MINY, TS_MAXY, 0, tft.height());

  /*
  Serial.print("("); Serial.print(p.x);
  Serial.print(", "); Serial.print(p.y);
  Serial.println(")");
  */

  if (p.y < BOXSIZE) {
     oldcolor = currentcolor;

     if (p.x < BOXSIZE) { 
       currentcolor = ILI9341_RED; 
       tft.drawRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     } else if (p.x < BOXSIZE*2) {
       currentcolor = ILI9341_YELLOW;
       tft.drawRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     } else if (p.x < BOXSIZE*3) {
       currentcolor = ILI9341_GREEN;
       tft.drawRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     } else if (p.x < BOXSIZE*4) {
       currentcolor = ILI9341_CYAN;
       tft.drawRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     } else if (p.x < BOXSIZE*5) {
       currentcolor = ILI9341_BLUE;
       tft.drawRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     } else if (p.x < BOXSIZE*6) {
       currentcolor = ILI9341_MAGENTA;
       tft.drawRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, ILI9341_WHITE);
     }

     if (oldcolor != currentcolor) {
        if (oldcolor == ILI9341_RED) 
          tft.fillRect(0, 0, BOXSIZE, BOXSIZE, ILI9341_RED);
        if (oldcolor == ILI9341_YELLOW) 
          tft.fillRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, ILI9341_YELLOW);
        if (oldcolor == ILI9341_GREEN) 
          tft.fillRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, ILI9341_GREEN);
        if (oldcolor == ILI9341_CYAN) 
          tft.fillRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, ILI9341_CYAN);
        if (oldcolor == ILI9341_BLUE) 
          tft.fillRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, ILI9341_BLUE);
        if (oldcolor == ILI9341_MAGENTA) 
          tft.fillRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, ILI9341_MAGENTA);
     }
  }
  if (((p.y-PENRADIUS) > BOXSIZE) && ((p.y+PENRADIUS) < tft.height())) {
    tft.fillCircle(p.x, p.y, PENRADIUS, currentcolor);
  }
}