ILI9328 TFT touch screen inaccuracy + bitmap problems

I’ve noticed my Chinese red touch screen (ILI9328 according to driver diagnostics, but advertised as ILI9325) has a slight inaccuracy problem when using the touch paint code. At coordinates near [0,0] it’s fine, but as X increases the drawing point gets increasingly further left from the stylus’ actual position. Picture of the issue and code are below:

Code:

#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_TFTLCD.h> // Hardware-specific library
#include <TouchScreen.h>

#if defined(__SAM3X8E__)
    #undef __FlashStringHelper::F(string_literal)
    #define F(string_literal) string_literal
#endif

// When using the BREAKOUT BOARD only, use these 8 data lines to the LCD:
// For the Arduino Uno, Duemilanove, Diecimila, etc.:
//   D0 connects to digital pin 8  (Notice these are
//   D1 connects to digital pin 9   NOT in order!)
//   D2 connects to digital pin 2
//   D3 connects to digital pin 3
//   D4 connects to digital pin 4
//   D5 connects to digital pin 5
//   D6 connects to digital pin 6
//   D7 connects to digital pin 7

// For the Arduino Mega, use digital pins 22 through 29
// (on the 2-row header at the end of the board).
//   D0 connects to digital pin 22
//   D1 connects to digital pin 23
//   D2 connects to digital pin 24
//   D3 connects to digital pin 25
//   D4 connects to digital pin 26
//   D5 connects to digital pin 27
//   D6 connects to digital pin 28
//   D7 connects to digital pin 29

// For the Arduino Due, use digital pins 33 through 40
// (on the 2-row header at the end of the board).
//   D0 connects to digital pin 33
//   D1 connects to digital pin 34
//   D2 connects to digital pin 35
//   D3 connects to digital pin 36
//   D4 connects to digital pin 37
//   D5 connects to digital pin 38
//   D6 connects to digital pin 39
//   D7 connects to digital pin 40

#define YP A3  // must be an analog pin, use "An" notation!
#define XM A2  // must be an analog pin, use "An" notation!
#define YM 9   // can be a digital pin
#define XP 8   // can be a digital pin

#define TS_MINX 150
#define TS_MINY 120
#define TS_MAXX 920
#define TS_MAXY 940

// For better pressure precision, we need to know the resistance
// between X+ and X- Use any multimeter to read it
// For the one we're using, its 300 ohms across the X plate
TouchScreen ts = TouchScreen(XP, YP, XM, YM, 300);

#define LCD_CS A3
#define LCD_CD A2
#define LCD_WR A1
#define LCD_RD A0
// optional
#define LCD_RESET A4

// Assign human-readable names to some common 16-bit color values:
#define  BLACK   0x0000
#define BLUE    0x001F
#define RED     0xF800
#define GREEN   0x07E0
#define CYAN    0x07FF
#define MAGENTA 0xF81F
#define YELLOW  0xFFE0
#define WHITE   0xFFFF


Adafruit_TFTLCD tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET);

#define BOXSIZE 40
#define PENRADIUS 3
int oldcolor, currentcolor;

void setup(void) {
  Serial.begin(9600);
  Serial.println(F("Paint!"));
  
  tft.reset();
  
  uint16_t identifier = tft.readID();
 if(identifier==0x0101)
      identifier=0x9341;
  if(identifier == 0x9325) {
    Serial.println(F("Found ILI9325 LCD driver"));
  } else if(identifier == 0x9328) {
    Serial.println(F("Found ILI9328 LCD driver"));
  } else if(identifier == 0x4535) {
    Serial.println(F("Found LGDP4535 LCD driver"));
  }else if(identifier == 0x7575) {
    Serial.println(F("Found HX8347G LCD driver"));
  } else if(identifier == 0x9341) {
    Serial.println(F("Found ILI9341 LCD driver"));
  } else if(identifier == 0x8357) {
    Serial.println(F("Found HX8357D LCD driver"));
  } else {
    Serial.print(F("Unknown LCD driver chip: "));
    Serial.println(identifier, HEX);
    Serial.println(F("If using the Adafruit 2.8\" TFT Arduino shield, the line:"));
    Serial.println(F("  #define USE_ADAFRUIT_SHIELD_PINOUT"));
    Serial.println(F("should appear in the library header (Adafruit_TFT.h)."));
    Serial.println(F("If using the breakout board, it should NOT be #defined!"));
    Serial.println(F("Also if using the breakout, double-check that all wiring"));
    Serial.println(F("matches the tutorial."));
    return;
  }

  tft.begin(identifier);

  tft.fillScreen(BLACK);

  tft.fillRect(0, 0, BOXSIZE, BOXSIZE, RED);
  tft.fillRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, YELLOW);
  tft.fillRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, GREEN);
  tft.fillRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, CYAN);
  tft.fillRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, BLUE);
  tft.fillRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, MAGENTA);
  // tft.fillRect(BOXSIZE*6, 0, BOXSIZE, BOXSIZE, WHITE);
 
  tft.drawRect(0, 0, BOXSIZE, BOXSIZE, WHITE);
  currentcolor = RED;
 
  pinMode(13, OUTPUT);
}

#define MINPRESSURE 10
#define MAXPRESSURE 1000

void loop()
{
  digitalWrite(13, HIGH);
  TSPoint p = ts.getPoint();
  digitalWrite(13, LOW);

  // if sharing pins, you'll need to fix the directions of the touchscreen pins
  //pinMode(XP, OUTPUT);
  pinMode(XM, OUTPUT);
  pinMode(YP, OUTPUT);
  //pinMode(YM, OUTPUT);

  // we have some minimum pressure we consider 'valid'
  // pressure of 0 means no pressing!

  if (p.z > MINPRESSURE && p.z < MAXPRESSURE) {
    /*
    Serial.print("X = "); Serial.print(p.x);
    Serial.print("\tY = "); Serial.print(p.y);
    Serial.print("\tPressure = "); Serial.println(p.z);
    */
    
    if (p.y < (TS_MINY-5)) {
      Serial.println("erase");
      // press the bottom of the screen to erase 
      tft.fillRect(0, BOXSIZE, tft.width(), tft.height()-BOXSIZE, BLACK);
    }
    // scale from 0->1023 to tft.width
    p.x = map(p.x, TS_MINX, TS_MAXX, tft.width(), 0);
    p.y = map(p.y, TS_MINY, TS_MAXY, tft.height(), 0);
    /*
    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 = RED; 
         tft.drawRect(0, 0, BOXSIZE, BOXSIZE, WHITE);
       } else if (p.x < BOXSIZE*2) {
         currentcolor = YELLOW;
         tft.drawRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, WHITE);
       } else if (p.x < BOXSIZE*3) {
         currentcolor = GREEN;
         tft.drawRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, WHITE);
       } else if (p.x < BOXSIZE*4) {
         currentcolor = CYAN;
         tft.drawRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, WHITE);
       } else if (p.x < BOXSIZE*5) {
         currentcolor = BLUE;
         tft.drawRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, WHITE);
       } else if (p.x < BOXSIZE*6) {
         currentcolor = MAGENTA;
         tft.drawRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, WHITE);
       }

       if (oldcolor != currentcolor) {
          if (oldcolor == RED) tft.fillRect(0, 0, BOXSIZE, BOXSIZE, RED);
          if (oldcolor == YELLOW) tft.fillRect(BOXSIZE, 0, BOXSIZE, BOXSIZE, YELLOW);
          if (oldcolor == GREEN) tft.fillRect(BOXSIZE*2, 0, BOXSIZE, BOXSIZE, GREEN);
          if (oldcolor == CYAN) tft.fillRect(BOXSIZE*3, 0, BOXSIZE, BOXSIZE, CYAN);
          if (oldcolor == BLUE) tft.fillRect(BOXSIZE*4, 0, BOXSIZE, BOXSIZE, BLUE);
          if (oldcolor == MAGENTA) tft.fillRect(BOXSIZE*5, 0, BOXSIZE, BOXSIZE, MAGENTA);
       }
    }
    if (((p.y-PENRADIUS) > BOXSIZE) && ((p.y+PENRADIUS) < tft.height())) {
      tft.fillCircle(p.x, p.y, PENRADIUS, currentcolor);
    }
  }
}

Changing TS_MAXX does not appear to have any effect. Is there some sort of calibration program I could run to get things back on track here? I’m intending to use this for touch-screen buttons, and I’m worried the user interface might not be accurate about the actual button area being pressed.

Also, I was hoping to display the actual buttons as ‘animated’ bitmap images. However, the board can’t seem to recognize any bitmaps I put on there, even the ‘tiger.bmp’ that seems to be a standard test for these display screens. Just returns ‘bad bmp’ 10 times, followed by ‘didnt find BMPimage’. Tried this on two different SD cards (one SDFat formatted, one not, both with only tiger.bmp on there) with the exact same result. Slightly modified code is below - only edit is to the bitmap list:

#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_TFTLCD.h> // Hardware-specific library
#include <SD.h>
#include <SPI.h>


// The control pins for the LCD can be assigned to any digital or
// analog pins...but we'll use the analog pins as this allows us to
// double up the pins with the touch screen (see the TFT paint example).
#define LCD_CS A3 // Chip Select goes to Analog 3
#define LCD_CD A2 // Command/Data goes to Analog 2
#define LCD_WR A1 // LCD Write goes to Analog 1
#define LCD_RD A0 // LCD Read goes to Analog 0
#define PIN_SD_CS 10 // Adafruit SD shields and modules: pin 10

#define LCD_RESET A4 // Can alternately just connect to Arduino's reset pin

// When using the BREAKOUT BOARD only, use these 8 data lines to the LCD:
// For the Arduino Uno, Duemilanove, Diecimila, etc.:
//   D0 connects to digital pin 8  (Notice these are
//   D1 connects to digital pin 9   NOT in order!)
//   D2 connects to digital pin 2
//   D3 connects to digital pin 3
//   D4 connects to digital pin 4
//   D5 connects to digital pin 5
//   D6 connects to digital pin 6
//   D7 connects to digital pin 7
// For the Arduino Mega, use digital pins 22 through 29
// (on the 2-row header at the end of the board).

// Assign human-readable names to some common 16-bit color values:
#define  BLACK   0x0000
#define BLUE    0x001F
#define RED     0xF800
#define GREEN   0x07E0
#define CYAN    0x07FF
#define MAGENTA 0xF81F
#define YELLOW  0xFFE0
#define WHITE   0xFFFF

Adafruit_TFTLCD tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET);
// If using the shield, all control and data lines are fixed, and
// a simpler declaration can optionally be used:
// Adafruit_TFTLCD tft;


#define MAX_BMP         10                      // bmp file num
#define FILENAME_LEN    20                      // max file name length

const int __Gnbmp_height = 320;                 // bmp hight
const int __Gnbmp_width  = 240;                 // bmp width

unsigned char __Gnbmp_image_offset  = 0;        // offset

int __Gnfile_num = 4;                           // num of file

char __Gsbmp_files[4][FILENAME_LEN] =           // add file name here
{
"tiger.bmp",
};
File bmpFile;

/*********************************************/
// This procedure reads a bitmap and draws it to the screen
// its sped up by reading many pixels worth of data at a time
// instead of just one pixel at a time. increading the buffer takes
// more RAM but makes the drawing a little faster. 20 pixels' worth
// is probably a good place

#define BUFFPIXEL       60                      // must be a divisor of 240 
#define BUFFPIXEL_X3    180                     // BUFFPIXELx3

void bmpdraw(File f, int x, int y)
{
    bmpFile.seek(__Gnbmp_image_offset);

    uint32_t time = millis();

    uint8_t sdbuffer[BUFFPIXEL_X3];                 // 3 * pixels to buffer

    for (int i=0; i< __Gnbmp_height; i++) {
        for(int j=0; j<(240/BUFFPIXEL); j++) {
            bmpFile.read(sdbuffer, BUFFPIXEL_X3);
            
            uint8_t buffidx = 0;
            int offset_x = j*BUFFPIXEL;
            unsigned int __color[BUFFPIXEL];
            
            for(int k=0; k<BUFFPIXEL; k++) {
                __color[k] = sdbuffer[buffidx+2]>>3;                        // read
                __color[k] = __color[k]<<6 | (sdbuffer[buffidx+1]>>2);      // green
                __color[k] = __color[k]<<5 | (sdbuffer[buffidx+0]>>3);      // blue
                
                buffidx += 3;
            }

      for (int m = 0; m < BUFFPIXEL; m ++) {
              tft.drawPixel(m+offset_x, i,__color[m]);
      }
        }
    }
    
    Serial.print(millis() - time, DEC);
    Serial.println(" ms");
}

boolean bmpReadHeader(File f) 
{
    // read header
    uint32_t tmp;
    uint8_t bmpDepth;
    
    if (read16(f) != 0x4D42) {
        // magic bytes missing
        return false;
    }

    // read file size
    tmp = read32(f);
    Serial.print("size 0x");
    Serial.println(tmp, HEX);

    // read and ignore creator bytes
    read32(f);

    __Gnbmp_image_offset = read32(f);
    Serial.print("offset ");
    Serial.println(__Gnbmp_image_offset, DEC);

    // read DIB header
    tmp = read32(f);
    Serial.print("header size ");
    Serial.println(tmp, DEC);
    
    int bmp_width = read32(f);
    int bmp_height = read32(f);
    
    if(bmp_width != __Gnbmp_width || bmp_height != __Gnbmp_height)  {    // if image is not 320x240, return false
        return false;
    }

    if (read16(f) != 1)
    return false;

    bmpDepth = read16(f);
    Serial.print("bitdepth ");
    Serial.println(bmpDepth, DEC);

    if (read32(f) != 0) {
        // compression not supported!
        return false;
    }

    Serial.print("compression ");
    Serial.println(tmp, DEC);

    return true;
}

/*********************************************/
// These read data from the SD card file and convert them to big endian
// (the data is stored in little endian format!)

// LITTLE ENDIAN!
uint16_t read16(File f)
{
    uint16_t d;
    uint8_t b;
    b = f.read();
    d = f.read();
    d <<= 8;
    d |= b;
    return d;
}

// LITTLE ENDIAN!
uint32_t read32(File f)
{
    uint32_t d;
    uint16_t b;

    b = read16(f);
    d = read16(f);
    d <<= 16;
    d |= b;
    return d;
}

void setup(void) {
  Serial.begin(9600);
  Serial.println(F("TFT LCD test"));

#ifdef USE_ADAFRUIT_SHIELD_PINOUT
  Serial.println(F("Using Adafruit 2.4\" TFT Arduino Shield Pinout"));
#else
  Serial.println(F("Using Adafruit 2.4\" TFT Breakout Board Pinout"));
#endif

  Serial.print("TFT size is "); Serial.print(tft.width()); Serial.print("x"); Serial.println(tft.height());

  tft.reset();

  uint16_t identifier = tft.readID();
  if(identifier==0x0101)
      identifier=0x9341;
  
  if(identifier == 0x9325) {
    Serial.println(F("Found ILI9325 LCD driver"));
  } else if(identifier == 0x4535) {
    Serial.println(F("Found LGDP4535 LCD driver"));
  }else if(identifier == 0x9328) {
    Serial.println(F("Found ILI9328 LCD driver"));
  } else if(identifier == 0x7575) {
    Serial.println(F("Found HX8347G LCD driver"));
  } else if(identifier == 0x9341) {
    Serial.println(F("Found ILI9341 LCD driver"));
  } else if(identifier == 0x8357) {
    Serial.println(F("Found HX8357D LCD driver"));
  } else {
    Serial.print(F("Unknown LCD driver chip: "));
    Serial.println(identifier, HEX);
    Serial.println(F("If using the Adafruit 2.4\" TFT Arduino shield, the line:"));
    Serial.println(F("  #define USE_ADAFRUIT_SHIELD_PINOUT"));
    Serial.println(F("should appear in the library header (Adafruit_TFT.h)."));
    Serial.println(F("If using the breakout board, it should NOT be #defined!"));
    Serial.println(F("Also if using the breakout, double-check that all wiring"));
    Serial.println(F("matches the tutorial."));
    return;
  }
  
  tft.begin(identifier);
  tft.fillScreen(BLUE);
  
  
  
  //Init SD_Card
  pinMode(10, OUTPUT);
   
  if (!SD.begin(10)) {
    Serial.println("initialization failed!");
    tft.setCursor(0, 0);
    tft.setTextColor(WHITE);    
    tft.setTextSize(1);
    tft.println("SD Card Init fail.");   
  }else
  Serial.println("initialization done."); 
}

void loop(void) {
     for(unsigned char i=0; i<__Gnfile_num; i++) {
        bmpFile = SD.open(__Gsbmp_files[i]);
        if (! bmpFile) {
            Serial.println("didnt find image");
            tft.setTextColor(WHITE);    tft.setTextSize(1);
            tft.println("didnt find BMPimage");
            while (1);
        }
   
        if(! bmpReadHeader(bmpFile)) {
            Serial.println("bad bmp");
            tft.setTextColor(WHITE);    tft.setTextSize(1);
            tft.println("bad bmp");
            return;
        }

        bmpdraw(bmpFile, 0, 0);
        bmpFile.close();
        delay(1000);
        delay(1000);
    }
    
}

Install libraries via IDE Library Manager.

Build both programs.
Copy-paste the "libraries and memory used" lines for each build. (like you have done with previous problems)

Then readers can reproduce your problem(s) by using the same library versions, and same library example sketches.

This applies to anyone with difficulties i.e.

  1. Post links to the hardware screen that you have bought
  2. Install libraries via IDE Library Manager.
  3. Enable verbose compile via IDE File->Preferences
  4. Always try the library examples first.
  5. Copy-paste just the "libraries and memory used" lines for a successful build.
  6. If you get build failures, attach the whole build report as a TXT file.
  7. Quote Library examples by name. The examples were installed with the library.
  8. If you make an edit to an example, just copy-paste your changes. So we can reproduce.

David.

EDIT: Realized I should probably run through this in list order to make sure I have everything.

Link to hardware board:
https://www.ebay.com/itm/KEYES-2-8-Inch-TFT-LCD-Touch-Screen-Module-240X320-for-Arduino-UNO-R3-Project/264161623971?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
(Note that this claims an ILI9325 driver, when according to diagnostics run in Arduino programs, what I received is actually an ILI9328).

All referenced libraries were uninstalled and reinstalled exclusively using the IDE library manager. The new library output is below (for the life of me, I can't find where the other versions of those header files are located):

Multiple libraries were found for "Adafruit_GFX.h"
Used: C:\Users\Jeremy\Documents\Arduino\libraries\Adafruit_GFX_Library
Multiple libraries were found for "Adafruit_TFTLCD.h"
Used: C:\Users\Jeremy\Documents\Arduino\libraries\Adafruit_TFTLCD_Library
Multiple libraries were found for "TouchScreen.h"
Used: C:\Users\Jeremy\Documents\Arduino\libraries\Adafruit_TouchScreen
Multiple libraries were found for "Adafruit_I2CDevice.h"
Used: C:\Users\Jeremy\Documents\Arduino\libraries\Adafruit_BusIO
Multiple libraries were found for "Wire.h"
Used: C:\Program
Multiple libraries were found for "SPI.h"
Used: C:\Program
Using library Adafruit_GFX_Library at version 1.9.0 in folder: C:\Users\Jeremy\Documents\Arduino\libraries\Adafruit_GFX_Library
Using library Adafruit_TFTLCD_Library at version 1.0.3 in folder: C:\Users\Jeremy\Documents\Arduino\libraries\Adafruit_TFTLCD_Library
Using library Adafruit_TouchScreen at version 1.1.0 in folder: C:\Users\Jeremy\Documents\Arduino\libraries\Adafruit_TouchScreen
Using library Adafruit_BusIO at version 1.4.1 in folder: C:\Users\Jeremy\Documents\Arduino\libraries\Adafruit_BusIO
Using library Wire at version 1.0 in folder: C:\Program Files
Using library SPI at version 1.0 in folder: C:\Program Files

I can't attach the bitmap I've been using for testing to this post, so here's a link to the page I took it from:

The SD card is readable from the shield and lists the correct files, as well as the SD card info using SDInfo and the listfiles tutorial from the Arduino website.

graphicstest.ino from the Adafruit_TFTLCD library works with no modifications.
touchscreendemoshield.ino from the Adafruit_TouchScreen library works with no modifications.
tftbmp.ino from the Adafruit_TFTLCD library works with no modifications for any loaded bmp image (including my custom bcktt.bmp and tiger.bmp).

The intended code from the manufacturer of the board (in my second post) for displaying bitmaps does not work, still giving the 'bad bmp' error.

So far, I'm 99% sure it's not a problem with the Arduino, shield, USB cable, or SD card. Therefore, it should be a problem with the code. Maybe I'm not editing some variable to properly search for these bitmap files?

You have a "Mcufriend-style" Uno Shield. The photos in your link show that it has an AMS1117 regulator on the pcb. i.e. like the old Mcufriend displays.

It also tells you the Touch pins.

Of course you have to compare the item on your desk with the photos in the link.

Anyway, it appears that the Adafruit_TFTLCD examples all work 100%.

So the only "problem" is the "unknown code" in #1.

I suggest that you adapt the Adafruit examples rather than try to use some "unknown code".

David.

Got in touch with the seller, who managed to get my code working by sending me their reference images. Still haven't got custom images to work, but I want to focus on displaying images more quickly. I'm not too fussed about instant (or faster than the human eye could see), but below 500 ms for a full-sized image would be ideal.

After comparing the two, I realized the tftbmp.ino sketch is exactly as fast (if not slightly faster), at about 2.75 seconds to display a full image, so I'll be using that. It's worth noting that most of the bitmaps I plan to display are smaller than the full size of the screen, which may make them display faster (save for the backgrounds).

That said, changing BUFFPIXEL on line 106 does not appear to decrease the display time - I experimented with values from 20 to 80 in increments of 20 and always got a full image display time of around 2.75 seconds This is on an Arduino Uno (I hope to move to Nano in the future but don't know if that's realistic given my other goals).

There are several libraries that support "Mcufriend Uno Shield" style displays.
Especially for common controllers like ILI9325 / ILI9328.

Many have examples for displaying BMP files from an SD.

Most will be faster than 2.75 seconds.

David.