ili9341 touch

[stan cartwright]

I am using the lgt328 ili9341 touch demo. It's interesting. I stripped it down to a minimum and it just draws circles where you touch the screen. here's the minimum code.

    #chip LGT8F328P
    #option explicit

    #include <glcd.h>
    #include <xpt2046.h>
    #include <LGT8F328P.h >

    '******************************************************************************************************
    'Setup the GLCD

    #define GLCD_TYPE GLCD_TYPE_ILI9341

    'Pin mappings for SPI - this GLCD driver supports Hardware SPI and Software SPI
    #define GLCD_DC       DIGITAL_8           ' Data command line
    #define GLCD_CS       DIGITAL_10          ' Chip select line
    #define GLCD_RESET    DIGITAL_9           ' Reset line
    #define GLCD_DI       DIGITAL_12          ' Data in | MISO    - Not used therefore not really required
    #define GLCD_DO       DIGITAL_11          ' Data out | MOSI
    #define GLCD_SCK      DIGITAL_13          ' Clock Line

    #define ILI9341_HARDWARESPI
    'Setup the XPT2046
    'Typical Calibration range for Software SPI when using XPT2046
    #define XPT2046XMIN   30
    #define XPT2046YMIN   25
    #define XPT2046XMAX   210
    #define XPT2046YMAX   225

    #define XPT2046_DI       DIGITAL_12          ' Data in | MISO
    #define XPT2046_DO       DIGITAL_11          ' Data out | MOSI
    #define XPT2046_SCK      DIGITAL_13          ' Clock Line
    #define XPT2046_CS       DIGITAL_2           ' Chip select line
    #define XPT2046_IRQ      ANALOG_5

    #define XPT2046_SOFTWARESPI
    #define LGT_XPT_HWSPIMODE  MASTER  'optionally can be MASTERSLOW

    'Main program
    GLCDRotate Portrait
    GLCDCLS TFT_BLUE
    SetCalibation_XPT2046 ( XPT2046XMIN, XPT2046XMAX, XPT2046YMIN, XPT2046YMAX, GLCD_WIDTH, GLCD_HEIGHT )
;    ScreenLayout

    dim Xconverge, Yconverge as Integer
    dim convergeCounter as byte
    do

      Xconverge = 0
      Yconverge = 0
      convergeCounter = 1

      do
          repeat 5
              'get the values -
              GetXY_XPT2046( XTouchPoint_XPT2046, YTouchPoint_XPT2046 )
          end Repeat
          'test for settling by testing for convergance
          if ABS( ( Xconverge - XTouchPoint_XPT2046 ) ) > 1  or  ABS( ( Yconverge - YTouchPoint_XPT2046 ) ) > 1  then
              Xconverge = XTouchPoint_XPT2046
              Yconverge = YTouchPoint_XPT2046
              convergeCounter++
          Else
              'converged
              exit do
          end if
      Loop
;      Flip the data to handle for the screen rotation
      YTouchPoint_XPT2046 = Current_GLCD_HEIGHT - YTouchPoint_XPT2046

           FilledCircle XTouchPoint_XPT2046, YTouchPoint_XPT2046, 3, TFT_LIGHTGREY

    loop

I don't understand the code. I can't see what convergeCounter++ is for.
Does YTouchPoint_XPT2046 = Current_GLCD_HEIGHT - YTouchPoint_XPT2046 need to be in the main loop?
It's a good gcb include but how does it work ?
What is

    'Typical Calibration range for Software SPI when using XPT2046
    #define XPT2046XMIN   30
    #define XPT2046YMIN   25
    #define XPT2046XMAX   210
    #define XPT2046YMAX   225

about please?
I notice an increasing x axis error as you touch screen further right??
The display is 240x320. The x axis error is a problem. I can do a youtube video to show the error.
ps #define GLCD_TYPE GLCD_TYPE_ILI9341 seems new.
Also why TFT_LIGHTGREY instead of ili9341 colours? asked before.

[Anobium]

Stan - how cool!

---

convergeCounter

convergeCounter is a method to ensure the pointer is in the same place within 1 returned pixel value

If reads the position of the event 5 times then if the read is with 1 pixel of the last one it exits the do loop - this stops the XPT sensor returning wild results.

---

It's a good gcb include but how does it work ?

The include is relatively simple.

1. Setups the ports etc and sets the interrupt
2. It sends the calibration data to the XPT
3. Take a load of samples by sending a request for a sample but for the LGT turn off harware SPI prior to request and restore SPI state after the request has completed.
4. Return an average of the sensor values

---

What is

'Typical Calibration range for Software SPI when using XPT2046
#define XPT2046XMIN   30
#define XPT2046YMIN   25
#define XPT2046XMAX   210
#define XPT2046YMAX   225

about please?

These are the calibration values. Use the original demo to set the returned values. See https://youtu.be/wN35LwRgOAQ

---

I notice an increasing x axis error as you touch screen further right??

Recalibrate please.

---

Also why TFT_LIGHTGREY instead of ili9341 colours? asked before.

TFT_LIGHTGREY is the same value as the ILI9341 constant. I created the ILI9341 constants before I was thinking about just using TFT_color_code_constants

:-)

[stan cartwright]

Nice one Anobium. Thinking a 50Hz timer interrupt for getting x,y touched. You mention 20ms before touch the screen.
The x,y is from where the circle is drawn so getting there.
I just want to test an x,y co-ordinate of a screen pressed position but in a program would need a way of getting the screen touched event.
I'm not the brightest crayon in the box so lots of thinking to do.
I got to try the mega328 interrupts with LGT328. TimerCalulator program ?? what to set it? Assume interrupt happen twice as fast??

[Anobium]

Check demos https://github.com/Anobium/Great-Cow-BASIC-Demonstration-Sources/tree/master/Interrupt_and_Timer_Solutions

[stan cartwright]

Your video https://www.youtube.com/watch?v=wN35LwRgOAQ explains a lot about the mechanics. Cheers.

[Anobium]

@Stan - I spotted some serial debug left in the XPT library. Get the latest patch for that library - the latest has the debug removed. Here is the URL

https://sourceforge.net/projects/gcbasic/files/Release%20Candidates/Patches/gcb%40syn/GreatCowBASIC/include/xpt2046.h/download

Replace the existing in the include folder.