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Forum Index : Microcontroller and PC projects : 3.2" ILI9341 SPI LCD has changed

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Volhout
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Joined: 05/03/2018
Location: Netherlands
Posts: 5072

Posted: 04:44pm 12 Jul 2025

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For my second Game*Mite I ordered a new 3.2" ILI9341 SPI LCD. I like the 2.8" but the 3.2 was just a bit bigger, and better for my old eyes.

I received the LCD to day, and at first glance it looked identical to the old one. But... the SD card would not work.

The board has a different layout. And I applied some fixes to make it work.

- There is a low drop regulator on the board. This regulator does not have any decoupling capacitors (there is not even a footprint for these). I decided to bypass the regulator (solder blob), and added a decoupling capacitor (1uF ceramic) directly at the SD card pins.

- There are no resistors in the SCK, MOSI and CS lines for the SD card. I did cut the lines and added these. Some may debate whether these are needed, but I have had reliable operation with these resistors in previous boards, so I put them in (they alter wave form and setup and hold timing).

- the transistor that drives the backlight has a base resistor, but the collector resistor is shorted (small trace between the pads of the footprint). This means that any current limitation in the backlight is depending on the gain and saturation of the transistor. For now I left it as is, but I may make a change later on.

So just a heads up for those who still buy ILI9341 displays. These changes may also pop up in the future on 2.8" and 2.4" displays as a form of cost reduction. And you may wonder why they don't work.

Regards,

Volhout

PicomiteVGA PETSCII ROBOTS

ville56
Senior Member

Joined: 08/06/2022
Location: Austria
Posts: 221

Posted: 06:17pm 12 Jul 2025

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Thanks for the info, Vollhout. Can you please attach a picture of the component side so one can identify the display as one of these "optimized" parts more easily.

Thanks,
Gerald

73 de OE1HGA, Gerald

stanleyella

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Joined: 25/06/2022
Location: United Kingdom
Posts: 2548

Posted: 07:14pm 12 Jul 2025

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they all work the same for me, I made my board take both sizes and prefer the bigger one... same res ... but larger

Volhout
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Joined: 05/03/2018
Location: Netherlands
Posts: 5072

Posted: 07:16am 13 Jul 2025

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Hi Gerald,

I don't have a picture of the old one. But this is the new one with my modifications.

Volhout

PicomiteVGA PETSCII ROBOTS

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2626

Posted: 08:48am 13 Jul 2025

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In the past to improve reliability people have been shorting out the resistors you added.

I have both types and they are both reliable. My guess is the resistors were intended to protect the SD card if used with an Arduino's 5V logic.

stanleyella

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Joined: 25/06/2022
Location: United Kingdom
Posts: 2548

Posted: 02:01pm 13 Jul 2025

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yeah you needed a logic level converter for arduino and ili9341

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