Hello,
I found two 3,2" TFT display, but having no closer specification. Based on label on backside it is ILI9341 320QDT with touch screen and SD card reader.
Trying to investigate, how to use with Uno (if even possible).
I do not really understand the pinout. I can identify pins for touch screen and SD card reader, but this is for me not imporatnat, I would like to use display function only.
There is a lot of digital pins (15), but not sure, if there is also some other communication options, like SPI.
Uno does not have so many digital inputs (maybe analog inputs would be possible to use) but still I would like to avoid using all these pins.
Can somebody recognise the board and help with minimal connection to Uno? Any suggestions on library to use?
I found a lot of pinouts and corresponding libraries on internet, however nothing identical to my.
I suppose there might be also 3.3V logic, so it make sense to use only if I have to convert just a "couple" of signals. I do not want to buy Mega board, or shields for, in that case it is better to buy some module with SPI communication directly and "recycle" this one.
Photo attached.
Thank you very much.
Milos.
Search for the pinot of your display. For example 3.2″ TFT pinout & connection to Arduino MEGA (or Due) | Dimdim's Blog
You can Google TFT_320QVT_9341 and TFT_320QDT_9341
They are both 3.3V displays with a 40-pin header.
You can buy 40-pin Adapter shield for Mega (or Due)
Your Uno does not have enough sockets for a Mega Shield.
The QVT version should work with UTFT model ILI9341_16
I think that the QDT version has 8-bit interface which is not supported by UTFT.
If it is 8-bit, the Uno could be ok if you provide 13 level shifter channels.
Some Uno clones have switchable 5V / 3.3V GPIO. Switch to 3.3V. This type of clone does not need level shifters.
David.
I googled for 4 hours, found a lot of setups with different displays and chips. But still not clever about this one.
I plan to use simple resistor voltage dividers to convert the logic, at least to test the functionality. But sure, reducing to very minimum of necessary signals would be welcome.
But still, can somebody tell me, which of the pins to connect to which of the Uno pins and what library to use so it works together?
I am not sure where or from whom I got these, it might be also for STM32.
Milos.
It is still a lot of resistors. You must use them on EVERY signal.
If you connect like Mcufriend shields, MCUFRIEND_kbv library will work out of the box with the 8-bit interface.
Run the LCD_ID_readreg sketch to verify your level-shifted wiring. (Sketch shows you the pin defines)
David.
Hi David,
thank you for answers. If I see correctly, Mcufriend shield has only 8 data pins. I have on the module 16. So I should connect just first 8, this will work?
Still 13 signals to be shifted in total. I can sacrifice one of the modules to check if not 5V tolerant, better than build up voltage level shifter for 13 signals 
Milos.
It "looks" as if you have only got 8-bit interface and it is connected to DB8 - DB15 pins.
You can check the pcb traces to DB0-DB7 and DB8-DB15 with a DMM.
Hey-ho. I have never owned a QDT display. And getting feedback from owners is uncommon.
Most of these 40-pin displays use DB0 - DB15 i.e. 16-bit
Best would be to hear from a QDT owner with Mega2560 40-pin Adapter.
Does it work with UTFT ILI9341_16 ?
Or do you need MCUFRIEND_kbv with USE_SPECIAL and USE_MEGA_8BIT_SHIELD ?
Or do you need MCUFRIEND_kbv with USE_SPECIAL and USE_MEGA_16BIT_SHIELD ?
David.
Edit. Google found this message which seems to confirm that QDT is 16-bit and not 8-bit.
So there is no point in trying to do anything with a Uno that does not have enough pins.
Or even a Mega without the Mega Adapter shield. 21 level shifters is a lot to hand-wire.
Hi David,
I am afraid that the interface most likely will be 16 bit.
In that case I will probably not handle with Uno.
Buying Mega or special shields will cost more then buying some proper display with correct shield already.
I tried DB0 - DB7 directly on 5V logic, it did not work. I should receive some voltage level shifter circuits, so I will try this later on once more with correct logic and also on DB8-15. Do not even have enough suitable resistors now 
Thanks a lot for your tips.
Milos.
A Chinese Mega clone and a Chinese Adapter are pretty cheap. You just have a LONG wait for delivery.
I agree that it would have been more sensible to buy a Uno display in the first place.
The LCD_ID_readreg sketch should work on the 16-bit bus. Just wire each signal line to match the defines (with 10k series resistors).
David.
david_prentice:
It is still a lot of resistors. You must use them on EVERY signal.
SIL resistor packs!
Go on Paul. You know that those can not be used as series resistors.
Yes you can use them as the "lower leg" of a potential divider. You still need independent resistors for the top legs.
Life is much simpler if you buy the correct Adapter shield.
David.
david_prentice:
Go on Paul. You know that those can not be used as series resistors.Yes you can use them as the "lower leg" of a potential divider. You still need independent resistors for the top legs.
You get "independent" gangs in groups of four.
They are known as Resistor-Packs. They are a different shape and size.
david_prentice:
They are known as Resistor-Packs. They are a different shape and size.
Not that much different!
I had rather assumed SMD style of package of 4x resistor
e.g. from Digikey product page
I have never used a 4x in SIL package. But I have used the 8x + common SIL package.
It is a lot of hard work to solder 21 potential dividers or even 21 series resistors.
Simpler to use proper integrated circuits like 74VHC245 or breakout boards from Sparkfun or Ebay.
By the time you have bought a Protoshield pcb, headers, resistors / chips, wire, ... you might just as well have bought a ready made Adapter Shield. (which will work first time)
Hey-ho. Level-shifting 4 or 5 channels is practical. Anything more is "too much work" for me.
YMMV.
David.
david_prentice:
Hey-ho. Level-shifting 4 or 5 channels is practical. Anything more is "too much work" for me.
Well, I do not doubt that at all, just tweaking your pre-conceived expectations. 
I appreciate those ideas. In fact I am awaiting a package from China with voltage level shifters as above and sure I will use them to make it running, to win! But then I will sure dissasemble this monster construction And use the shifters for something more sensefull.
Milos.