Cee'z Blog

Thank you so much for this entry. I have been searching the web for a whole day to get this touchscreen running, edited code and was not abled to get rid of that white stripe on the left side and now it works perfectly because of your help :)

Thank you very much I have the ST7783 version of the same thing and the touchscreen input was exactly backwards, your change to TouchScreen.cpp fixed it! thanks!

Found something that removed the requirement for calibration, this may help you too.
This guy says the screen may be rotated 180degrees out of phase with the touchscreen, which is what I experienced.
https://mentaladventuresofnanoborg88.wordpress.com/2014/08/04/finally-got-the-touchscreen-shield-to-work/
“The touch pad was rotated 180 degrees from the display so adding tft.setRotation(2); in the setup before tft.initDisplay(); will line the two up again.”
This fixed it for me.
It would be nice to have some uniformity to setting up these little units, but I got mine barely used for less than $3 USD on ebay, I guess the last owner didn’t want to mess with it. Not bad for the price.
Thanks

You are my new god! I have been working for days on finding a library that would bring my LCD display to life. I finally got the chip identified to LGDP4535 and Google led me to you. Now it works perfectly even the reverse touch is fixes. Thank you very much for spending the time solving this an sharring it with us.

Dear Ceez,

You are a life saver. Got this LCD from amazon and got it working with your library. There is still one thing left unsolved -the touch screen part. There is no touch screen library in your attached code and I tried many versions from online. Never can draw anything with paint sketch. Can you elaborate?

Thanks in advance for your assitance.

Tony

Thank you for uploading the library, Ceez. The touch screen part is still not working. All the samples in your library displayed fine. It just does not respond to touching (such as Paint and Keypad). After uploading the samples from TouchScreen library, some x,y,pressure display and scrolls in Monitor. Is this a bad LCD or something else I am missing? any thoughts?

Thanks again for eveything.

Tony

Hello Ceez,

Thanks gain for your prompt help. I did download the new sketch. If I pressed the lower right corner (where the resistive ribbon extends out) hard and pressed the lower left corner (where the right box resides), I can get some red dots, occationally. I think I got a bad touch screen. Will try to get another one and give it a try.

Thanks gain for everything.

Tony

Bad luck. Most shields are designed for Arduino Uno and doesn’t work well on Arduino Mega or even doesn’t work at all.

I don’t have Arduino Mega at hand, but google shows that SPI pins are different between Arduino Uno and Mega
http://www.ceezblog.info/images/blog/ArduinoMega2560_pinout.png
http://www.ceezblog.info/images/blog/ArduinoUno_R3_Pinouts.png

We need SPI (D11, D12, D13 of Uno) to communicate with SD card and sometime with the LCD TFT, but with this shield it uses 8-bit bus interface (LCD_D0 - LCD_D7) instead of SPI. That is why only LCD works but SD card doesn’t. But I think touchscreen should work too, because it needs 2 digital pins pull up to Vcc and 2 analog pins to get read of x-axis, y-axis of touch-point.

I have some sample codes in “Main library for LGDP4535” that should work with SD lib and CeezTouchScreen lib, you can check it out.
The touchscreen use 4 pins :

#define YP A1  
#define XM A2  
#define YM 7   
#define XP 6

Anyway, touchscreen has crap quality. So, don’t put high hope for this.

thanks man :-) you saved me a lot of time! cheers….

Very nice!
Thanks for the sketch.
I am sure many people will love this!
I will test it and put it in my post if i have your permision :)

I also like your thinking.

Anyway, I want to implement rotate feature in touchscreen lib in order to make it works better in lanscape mode. It’s not perfect yet. I will improve it when I have free time.

Yes. It’s designed as a Uno shield and it should work fine like plug and play with the right library of course

I have found a way to make the SD card work with an Arduino Mega. The problem is, that the shield is for an UNO, and the Mega uses other pins for the SD card.

I used the normal “SD.h” Library and my SD-setup looks as follows:

//Setting up the SD card reader
Serial.print("Initializing SD card...");
if (!SD.begin(10, 11, 12, 13))
{
   	Serial.println("initialization failed!");
    	return;
}
  	Serial.println("initialization done.");

Im in no way pro at C++, but this works with my Data logger projekt.

That is what tag [code] is invented for ;)

Thank you! worked right out of the box for the 4535 display I received from ebay! saved me a lot of time. Thank you again :)

Actually, it worked, but I update the zTouchScreen lib and forgot to update these examples in the TFT-LGDP4535 lib.
I think access variables directly like that would not be a good practice in C++ generally. So I put up a function to do the job.

ts.InitVariable(0, 240, 320, TS_MINX, TS_MAXX, TS_MINY, TS_MAXY, MINPRESSURE, MAXPRESSURE);

Read README.txt and header file for more info about public function that you can use.

One thing comes up: wrong pin config for touchscreen

Try
#define YP A3
#define XM A2
#define YM 9
#define XP 8

You can use a VOM meter to trace the pins of touchscreen.
Or try to find 2 pairs of pins which have about 300 Ohm across each pair

Hey Ceez,

I tested the display with all of your files from your post. I tried to run the calculator example from user Jason Church here, but for me is it not possible to have the touch feature on the correct positions. I think there is some parameters not fine for my touchpad.

I use the same panal as you and I’m happy if you could give a short statement about that.

Thanks allot for your post here. This is the first useful page withe information about that lcd.

Best regards
Mia

Hey Ceez,

thank you allot. I measured 400 Ohm between theese pins, but I’ll try to take a look again for this. You’re right with the pins A3/A2/9/8. That is exactly the configuration I used in my code:

/***********************************************************
Example 6: Calculator
File version: 1.0
Update: using CeezTouchScreen lib
Description:
************************************************************/

#include <Adafruit_GFX.h>    // Core graphics library
#include <LGDP4535.h>        // Hardware-specific library
#include <zTouchScreen.h>

// 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

// If using the shield, all control and data lines are fixed
LGDP4535 tft;

#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

// your calibrated value should look like this
#define TS_MINX 120
#define TS_MINY 160
#define TS_MAXX 840
#define TS_MAXY 920

// un-comment this line to enable blue dot on touch point
//#define DEBUG

#define PENRADIUS 3
#define MINPRESSURE 10
#define MAXPRESSURE 1000
// 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, 400);

int matrix[5][4] =
{ {15, 16, 12, 24},
  {1, 2, 3, 23},
  {4, 5, 6, 22},
  {7, 8, 9, 21},
  {0, 10, 11, 21}
}
;

char matrixc[5][4] =
{ {'O', 'C', '<', '/'},
  {'1', '2', '3', '*'},
  {'4', '5', '6', '-'},
  {'7', '8', '9', '+'},
  {'0', '.', '=', ' '}
}
;

long result, input, mem;
byte op;
boolean in;

void setup(void) {

  // initiate these variable for calculation correct point
  // ts.min_x = TS_MINX;
  // ts.min_y = TS_MINY;
  // ts.max_x = TS_MAXX;
  // ts.max_y = TS_MAXY;
  // ts.width = 240;
  // ts.width = 320;
  // ts.orientation = 0; // rotate 180 degree

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

  tft.reset();

  uint16_t identifier = tft.readID();
  Serial.print(F("LCD driver chip: "));
  Serial.println(identifier, HEX);
  if (identifier == 0x4535)
    Serial.println(F("Using the library LGDP4535.nnPress the keypad to display number:"));
  else Serial.println(F("This is not the driver chip LGDP4535.nForce using library LGDP4535..."));
  Serial.println();
  tft.begin();
  drawGUI();
  input = 0;
  updateInput();
}

void drawGUI()
{
  tft.fillScreen(BLACK);
  int i, j;

  for (i = 0; i <= 3; i++)
    tft.drawFastHLine(1, 58 + i * 52, 238, WHITE);
  tft.drawFastHLine(1, 58 + 4 * 52, 178, WHITE);
  tft.drawFastHLine(1, 58 + 5 * 52, 238, WHITE);

  for (i = 0; i <= 3; i++)
    tft.drawFastVLine(1 + i * 59, 58, 266, WHITE);
  tft.drawFastVLine(238, 58, 260, WHITE);

  for (j = 0; j < 5; j++)
    for (i = 0; i < 4; i++)
    {
      switch (matrixc[j][i])
      {
        case 'O':
          tft.drawChar(58 * i + 14, 58 + 52 * j + 16, 'A', RED, BLACK, 3);
          tft.drawChar(58 * i + 32, 58 + 52 * j + 16, 'C', RED, BLACK, 3);
          continue;
        case '<':
          tft.drawChar(58 * i + 14, 58 + 52 * j + 16, '<', YELLOW, BLACK, 3);
          tft.drawChar(58 * i + 29, 58 + 52 * j + 16, '-', YELLOW, BLACK, 3);
          continue;
        case '+':
          tft.drawChar(58 * i + 22, 100 + 52 * j, matrixc[j][i], YELLOW, BLACK, 3);
          continue;
        default:
          tft.drawChar(58 * i + 22, 58 + 52 * j + 16, matrixc[j][i], YELLOW, BLACK, 3);
      }
    }
}

void updateInput()
{
  tft.fillRect(1, 10, 240, 40, BLACK);
  tft.setCursor(1, 10),
                tft.setTextColor(GREEN, BLACK);
  tft.setTextSize(3);
  tft.print(input);
}

void updateResult()
{
  tft.fillRect(1, 10, 240, 40, BLACK);
  tft.setCursor(1, 10),
                tft.setTextColor(GREEN, BLACK);
  tft.setTextSize(3);
  tft.print(result);
}

void updateOp()
{
  tft.fillRect(220, 10, 240, 40, BLACK);
  tft.setCursor(220, 10),
                tft.setTextColor(GREEN, BLACK);
  tft.setTextSize(3);
  if (op == 1) tft.print("+");
  if (op == 2) tft.print("-");
  if (op == 3) tft.print("*");
  if (op == 4) tft.print("/");
}

void loop(void) {
  // Recently Point was renamed TSPoint in the TouchScreen library
  // If you are using an older version of the library, use the
  // commented definition instead.
  // Point p = ts.getPoint();
  int x, y;
  static int anterior = 0, actual;
  static unsigned long int tanterior = 0, tactual = 0;
  TSPoint p = ts.getPoint();

  //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)
  {

    x = (4 * p.x) / tft.width(); //0 - 3
    y = (5 * (p.y - 52)) / (tft.height() - 52); // 0 - 5

    actual = matrix[y][x];
    tactual = millis();
    if (tactual - tanterior > 1000)
    {
      tanterior = tactual;
      anterior = -1;
    }

    if (actual != anterior );
    {
      Serial.println(actual);
      anterior = actual;

      //we got actual here as our touchpoint
      switch (actual)
      {
        case 0:
        case 1:
        case 2:
        case 3:
        case 4:
        case 5:
        case 6:
        case 7:
        case 8:
        case 9:
          if (in == false) input = 0;
          in = true;
          input = input * 10 + actual;
          updateInput();
          break;
        case 15: //AC
          input = 0;
          mem = 0;
          result = 0;
          op = 0;
          in = true;
          updateInput();
          break;
        case 16:
          input = 0;
          in = true;
          updateInput();
          break;
        case 12:
          // working on it later
          input = input / 10;
          break;
        case 21:
          op = 1;
          mem = input;
          input = 0;
          in = false;
          updateOp();
          break;
        case 22:
          op = 2;
          mem = input;
          input = 0;
          in = false;
          updateOp();
          break;
        case 23:
          op = 3;
          in = false;
          mem = input;
          input = 0;
          updateOp();
          break;
        case 24:
          op = 4;
          mem = input;
          input = 0;
          in = false;
          updateOp();
          break;
        case 11: // =
          result = input;
          if (op == 1) result = mem + input;
          if (op == 2) result = mem - input;
          if (op == 3) result = mem * input;
          if (op == 4) result = mem / input;
          op = 0;
          //          input = 0;
          mem = result;
          in = true;
          updateResult();
          break;
      }

#ifdef DEBUG
      tft.fillCircle(p.x, p.y, PENRADIUS, BLUE);
#endif
    }

  }
}

I’m a beginner in coding for arduino and will check again. The touch funktion works, but the positions of the touches are wrong.

I think it’s only a little thing I missed in the code.

After testing I would write here and give you a featback about that.

Best regards
Mia

Thank you so much :-)

As I said, I’m a beginner and now I able to start with my own code for some projects.

In

 ts.InitVariable(2, 240, 320, TS_MINX, TS_MAXX, TS_MINY, TS_MAXY, MINPRESSURE, MAXPRESSURE);

I use the rotation for 180 degree. Maybe I changed it in the <zTouchScreen.h>.

Thank you again. You’re blog is saved in my browser ;-)

Mia

Are you sure yours is lgdp4535 one ?

In the software yes. But in the hardware, I don’t think so. Its a resistive touch screen, cheap one. One finger, two fingers or the whole palm, it still registers as one single point with some dummy pressusure value. Totally not reliable.

Ceez

Did anybody here make the SD card work with Arduino Mega 2560? I have no problem with Uno, but lost with Mega.

Thanks in advance for any help.

Tony

Ceez,

awesome, great work…

Sounds very good. I’ll give em another try just in a few minutes. :-)

Thank you very much.

Br

Guido

Take a quick look on the SPI library SPI.h, SPI.cpp (hardware/arduinoavr/librariesSPI) and I find nothing for SOFTWARE SPI. My Arduino IDE version is 1.65. So, I suspect the SD lib from adafruit won’t work either, even they have some config option for changing the SPI pins for using SOFTWARE SPI.

I take back what I said. I saw some SPI bitbang functions in SD-master/utility/Sd2Card.cpp look like the same code as TFT display ST7753

inline void ST7735::spiwrite(uint8_t c)
{
  //Serial.println(c, HEX);
  if (hwSPI) {    // if using Hardware SPI
    SPI.transfer(c);
  } else {    // if not using Hardware SPI
    // Fast SPI bitbang swiped from LPD8806 library   <--- COPY AND PASTE ???
    for(uint8_t bit = 0x80; bit; bit >>= 1) {
      if(c & bit) dataport->PIO_SODR |= datapinmask;
      else        dataport->PIO_CODR |= datapinmask;
      clkport->PIO_SODR |= clkpinmask;
      clkport->PIO_CODR |= clkpinmask;
    }
  }
}

And this code is found on SD-master/utility/Sd2Card.cpp

  static void spiSend(uint8_t b) {
    if (clockPin_ == -1) {
      #ifndef USE_SPI_LIB
        SPDR = b;
        while (!(SPSR & (1 << SPIF)));
      #else
        SPI.transfer(b);
      #endif
    } else {
      noInterrupts();
      // Fast SPI bitbang swiped from LPD8806 library <--- COPY AND PASTE ???
      for (uint8_t i = 0; i < 8; i++) {
        *clkport &= ~clkpinmask;
        if (b & 0x80)
          *mosiport |= mosipinmask;
        else
          *mosiport &= ~mosipinmask;
        *clkport |=  clkpinmask;
        b <<= 1;
      }
      nop;nop;nop;nop;
      *clkport &= ~clkpinmask;
      
      interrupts();
    }
  }

That is funny, it look like the job of copy and paste :D . Anyway, I think it should work. Sorry I can’t be more helpful since I don’t have a Mega board at hand.

Hi Ceez,

Got it working, finally. You were right! I post the step here http://tech.memoryimprintstudio.com/access-sd-cards-from-tft-lcd-shield-using-arduino-mega-2560-soft-spi/.

Thanks again.

Tony
——————————–
Memory Imprint Studio

Can you explain where the text “rotate” is found. I have my screen in landscape and text is in portrait? the default demo rotates the whole screen but “https://learn.adafruit.com/downloads/pdf/2-8-tft-touchscreen.pdf” suggests there is a rotate command? thanks

Hi Ceez,

Can you give some general guidance on how to make this library work with LGDP4535? https://github.com/ginge/GuiLibrary It uses Adafruit core library.

Thanks

Tony

Thanks, Ceez. I got the display working fine. Fixing the touch screen coordinate now. Will keep you updated.

Tony

Pingback from http://thdarduino.blogspot.de/2015/12/freeduino-serial-v20-bausatz.html

I would like to know how many pins are free so I can work with them and if the I2C is functional? I noted that on Arduino Uno even if I don’t use the sdcard function I can’t use pin #3. Thanks for your hard work!

First, you need to know your TFT LCD uses SPI or 8bit/16bit parallel or i2c connection. It is easy: judge from the labels of the pins, it says SDA, SCK or SCLK, MOSI, MISO or D0, D1, D2…D7 so you will know it uses what kind of connection.

Then you search for a library that support that kind of connection, even it is not meant for your TFT LCD. The library will provide some functions that send/receive data to the LCD include a fuction that will read ID of TFT LCD, something like

LGDP4535 tft; 
void setup(void) {
  Serial.begin(9600);
  Serial.println(F("TFT LCD test - Graphic Test"));
  tft.reset();
  uint16_t identifier = tft.readID();
  Serial.print(F("LCD driver chip: "));
  Serial.println(identifier, HEX);

You will find similar code in the samples of that library.
Once you can make your TFT LCD talks, everything become easier unless your TFT LCD uses a graphic driver that no library has been written for it yet.

One more thing, most TFT LCD only accepts 3v3 TTL signal, 5v TTL signal from Arduino won’t work but lucky it won’t kill the LCD.

Judge on the link, it is 8 bit parallel one.

Have you tried this library https://forum.arduino.cc/index.php?topic=327294.msg2292602#msg2292602 yet ?

I’ve just take a quick look at the code, and found example RGB_TO_565 just like the picture on Taobao. I beleive this library is the right one for you.

Anyhow, you said not much success, and you got the LCD ID 0×0303. I think you actually got some code that works, proof is you success comunicate with your TFT LCD. All you need now is the right initialization code to “start-up” your TFT LCD.

Did you try to listen on serial port for debug information of the sample sketch, or even better, the ID of the TFT screen?

As far as I know, TFT shield usually uses parallel connection or SPI connection. Mostly cheap TFT shields use 8-bit parallel connection. Check the label of pins on the back for connection type. usually the command to get the ID is the same to most of TFT shield. If you can get the ID everything will be easier.

To be honest, it is almost no way to tell if the tft still work or fail, except you are able to communicate to the tft screen. Assume yours is a tft shield, yes? Then there are 2 things should take in account: wrong library and yours is not Arduino Uno but arduino mega or leonardo or something else.

1/ Double check if the label of the pins on your the TFT shield are in exact order to the one in picture. Picture is better.

2/ If “YES” then try sample “graphicstest” and tell me if it shows “LCD driver chip: 0×4535”. Again picture is better.

I doubt it will show 0×4535 for the chip ID. Or maybe It doesn’t show anything on serial monitor at all.

If “NO” for either one of two questions, I am unable to help you since the only TFT shield I have is this TFT with 4535 chipset. You need professional help like this guy https://forum.arduino.cc/index.php?topic=366304.msg2524865#msg2524865

Anyway, It won’t go anywhere without knowing the exact chipset of your TFT shield or just trying random libraries from the internet while crossing your fingers.

It doesn’t compile or it compiles and shows white screen?
Are you sure yours is 4535? Run example and open serial monitor (9600 baud rate) and see the results.

Read comments above. I know it’s long, but the answer’s probably up there.

Or you’ll another tutorial on Mega board here http://tech.memoryimprintstudio.com/arduino-with-a-lgdp4535-tft-lcd-touch-screen/

Oh i have to add that i used this TFT in an Arduino UNO and it worked (just that one axis was inverted) with your programs.

i got the Display problem solved, now it works partially ok. But now i have a problem with my X axis, its inverted xD, do you know how can i solve it?

can you post pin description of ILI9341 2.8” TFT display?
Thanks in advance.

The sield uses most pins, only a few left - what about the connection labeled {COM1} at the end of the board? What is it for? Can it be used as a “break-out” connection for the display, to free up the pins on the Uno?

My board is labeled HXJ002 rather than mcufriend, and identifies as an ILI8341. There are 18 open solder pads (2×9) on the end of the circuit board, where it extends past the glass, labeled COM1. Most appear to go to the ribbon cable connector, with a couple going to U2/U3 and at least 1 to the SD.
Is it possible to identify these pins? I suspect this would be the pins for a Mega, which shows a header across its end perpendicular to the normal Uno headers.

I see what you mean

I think they are extra pins for 18bit interface, 16bit interface (D8 to D17) and SPI interface of the driver chip ili9341 (LGDP4535 has these interfaces too). Those pins go to SD card must be SPI pins of the driver, but I guess it connect to D13, D12, D11 on Arduino via level shifter U2.

If you can trace these pins CON1 to the yellow flex cable and also has the pinout of the that flex cable, you can determine what function of these pins. And so you can change the interface of your TFT following the datasheet of ili9341 page 26 https://cdn-shop.adafruit.com/datasheets/ILI9341.pdf . And yes, if you can find pin IM0 to IM3 of the the TFT driver you are able to use this shield as an breakout board by forcing it to run on SPI interface.

Never done this nor having that much curiosity to take control completely of the TFT shield, just some possibilities that I can think of, but anyhow these pins are pretty much useless to me as it takes to much effort to use these pins. Anyway, you can get a breakout TFT screen with SPI interface for half price of the TFT shield.