Problem with new TFT display

Other Hardware Displays
21

Try using primary colors; red, green, blue, to show from where you are calling the fillScr() and setBackColor()

You have eleven setBackColor() calls. That's only 11 test runs.

The only place you use grey is "noon" function.

22

I am not sure I understand what you mean by try using primary colors. I first set fillscr and set backcolor in my inittftdisplay during setup

23

For testing, use red (255, 0, 0) or green (0 255, 0) or blue (0, 0, 255) rather than black or grey as the coloring to verify your TFT calls are correct.

24

Red Green Blue is displayed normal black gives a dark grey screen and (R,G,B) = 128 128 128 gives a very light grey color (almost whiter)

25

You searching for a background() or a fill() that is making the screen grey... to find which bg() or fill(), use one strange color (not black or grey) to find where "grey bg" happens.

26

I already know what makes the screen grey and it is when set to black when the tft is configured. Here is my current code that first setup the display

void	InitTFTDisplay()
{
	myGLCD.InitLCD(LANDSCAPE);
	myGLCD.clrScr();
	
	TestColor();

	myGLCD.fillScr(255, 255, 255);
	myGLCD.setBackColor(255, 255, 255);
	myGLCD.setColor(0, 0, 0);
}

void TestColor()
{
	myGLCD.setFont(Grotesk32x64);
	myGLCD.setContrast(64);
	myGLCD.fillScr(0, 0, 0);				//This makes the screen grey
	myGLCD.setBackColor(0, 0, 0);
	myGLCD.print("Black", 0, 0);
	delay(5000);
	myGLCD.fillScr(128, 128, 128);
	myGLCD.setBackColor(128, 128, 128);
	myGLCD.print("Grey ", 0, 0);
	delay(5000);
	myGLCD.fillScr(255, 0, 0);
	myGLCD.setBackColor(255, 0, 0);
	myGLCD.print("Red  ", 0, 0);
	delay(5000);
	myGLCD.fillScr(0, 255, 0);
	myGLCD.setBackColor(0, 255, 0);
	myGLCD.print("Green", 0, 0);
	delay(5000);
	myGLCD.fillScr(0, 0, 255);
	myGLCD.setBackColor(0, 0, 255);
	myGLCD.print("Blue ", 0, 0);
	delay(5000);
}

Here I can clearly see the screen is grey when set to black

27

I agree that you know how. Searching for "where" (and "why") is "grey" called when you explicitly call for "black." The use of "primary colors" is to find "when."

... aha...

I just saw "setContrast()" immediately before "fillScr()"... at about 1/4 of max value (64/255)... at max value. To me "contrast" changes the "fidelity" (range of HIGHEST to LOWEST)... this could be washing-out (raising your lowest value "0,0,0" to a lowest of "0+64,0+64,0+64" (dark grey). Would you see what happens when that setContrast() value is "0"?

This is the setContrast() function from the library .cpp...

void UTFT::setContrast(char c)
{
	cbi(P_CS, B_CS);
	switch (display_model)
	{
	case PCF8833:
		if (c>64) c=64;
		LCD_Write_COM(0x25);
		LCD_Write_DATA(c);
		break;
	}
	sbi(P_CS, B_CS);
}

It looks like it takes your value (maximum of 64) and writes (something) to the TFT... and then some interrupt handler or pushing/popping data to/from the stack (cbi...sbi).

[edit]

... and if the controller chips are different, specifically a PCF8833 controller, the TFT with the controller will be effected by setContrast(), and the other TFT probably does not have the controller (or vice-versa).

[/edit]

28

None or very little difference setting contrast to 0

I have another idea. On the back of the TFT are three jumpers for back light. On my old TFT the PWM is closed by a surface mounted resistor. But on my new it is instead LED_A. Could that be it ? To strong back light on the new TFT ?

29

I have not seen TFT with a backlight. I could be wrong (again).

What happens without calling setContrast()?

If text can be black, so too should be background.
When you set (fill?) a section of the background to red or green or blue, is the rest of the screen black or grey? If black, then, at what point of decreasing the color does the background turn grey?

30

Same thing. Actually setcontrast is new test. When I started the thread I had no setContrast call.

31

Have you made a minimal sketch for the tft?
That tft wants something abnormal. It might be written in the datasheet.

32

I have noticed another thing. The angle from which I look at the display affect how bright the screen is. When looking straight ahead with black background and lot of red text the background does indeed look rather black. But that black turns more towards grey if looked at from an angle

33

Sounds normal. The only screen I find without this effect is the 1" OLED.

I wonder if there is a hardware (potentiometer) contrast adjust.

34

No potentiometer