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Arne
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Joined: 05/01/2025
Location: Germany
Posts: 22

Posted: 05:29pm 29 Mar 2025

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Has anyone experience with the following 3.5 inch capacitive touch display:

Touch and sd-card are working fine. Due no special display driver for the ST7796S
for PicoMite is available I tested following drivers:

ILI9481:
It has a white background,displays wrong colors and is slow

ILI9488:
It has a white background,displays wrong colors and is slow

ST7789:
Is for 240x240 res. only, displays mirrored ?

Is there a way to adapt one of the a.m drivers to work properly/faster ?

Arne

ville56
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Joined: 08/06/2022
Location: Austria
Posts: 217

Posted: 08:59pm 29 Mar 2025

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what exactly do you mean with "slow"? Do you have any timing info, e.g. how many msec it takes to write a big box with color onto the display or load a jpg image? 480x320 with ILI9488 for me takes over 200 msec. There ist a lot of data to be transfered over the SPI bus.

You will also get some speed gain if you crank up the cpuspeed, but don't expect too much.

Gerald
Edited 2025-03-30 17:06 by ville56

73 de OE1HGA, Gerald

Arne
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Joined: 05/01/2025
Location: Germany
Posts: 22

Posted: 10:29am 30 Mar 2025

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Gerald thank you for your answers,

I have raised the cpu speed, now it is faster. My main problem is that the colors are not correct. They seem to be inverted. I did not find a command to manipulate the color palette.

Do you have any idea ?

Arne

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 10067

Posted: 10:35am 30 Mar 2025

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Don't know if it will work as the ST7796 isn't supported, but have you tried the INVERT parameter - manual page 55/56

Arne
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Joined: 05/01/2025
Location: Germany
Posts: 22

Posted: 04:07pm 30 Mar 2025

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@Peter

In the PicoMite user manual on page 55/56 I did not find Information about the INVERT parameter?
After your hint I tried „RGB((RED% XOR 255),(GREEN% XOR 255),(BLUE% XOR 255))“ to invert the data.
This is working within the programming. At the console/editor I can live with the inverted colors.

Thanks Arne

matherp
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Location: United Kingdom
Posts: 10067

Posted: 04:11pm 30 Mar 2025

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OPTION LCDPANEL ILI9488, OR, DC, RESET, CS [,BL] [,INVERT]

e.g. OPTION LCDPANEL ILI9488,L,GP0,GP1,GP2,,INVERT

same for all the other SPI displays
Edited 2025-03-31 02:11 by matherp

Arne
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Joined: 05/01/2025
Location: Germany
Posts: 22

Posted: 04:47pm 30 Mar 2025

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@Peter

Now its working perfect. Thanks a lot!

Arne

matherp
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Location: United Kingdom
Posts: 10067

Posted: 05:20pm 30 Mar 2025

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Which type works? ILI9481, 9488? I'll include a reference in the manual

ville56
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Joined: 08/06/2022
Location: Austria
Posts: 217

Posted: 05:38pm 30 Mar 2025

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Peter, i've used both controllers and they are working. The only thing to look for is if the display is TFT or IPS. Ususlly for IPS panels the INVERT parameter must be used. Often it is also marked on the plastic bag that the normal driver does not display correct colors.

Gerald

73 de OE1HGA, Gerald

Arne
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Joined: 05/01/2025
Location: Germany
Posts: 22

Posted: 06:42am 31 Mar 2025

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Hello,

I use the IPS display. ILI9488 AND ILI9481IPS are working. I prefer ILI9488 because it supports transparent text.

Arne

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