I have recently purchased a 3.5 inch TFT LCD which is an 8 bit display that uses an ILI9486/ST7796 driver chip. The display works fine for both the R4 and R3, and the touch does indeed work when tested with an R3, but not on the R4.
When calibrated using a fork of the MCUFriend library known to work well with the R4, this error message pops up:
TouchScreen.h GFX Calibration
Not possible to diagnose Touch pins on ARM or ESP32
ID = 0x9486
Does anyone have any clue as to what I need to change/add to get this display working?
I used this tutorial:
General Information on the display:
http://www.lcdwiki.com/3.5inch_Arduino_Display-UNO#Product_Documentation
Here is the data sheet for the display:
http://www.lcdwiki.com/res/MAR3501/QD-TFT3502%20specification_v1.1.pdf
And the data sheet for the ILI9486 driver:
http://www.lcdwiki.com/res/MAR3501/datasheet_ILI9486.pdf
Touch on the R4 with an LCD shield is certainly possible; I'm looking at it right now. I played around with this back in the spring and once I'd added support for the R4s to MCUFRIEND_kbv/utility/mcufriend_shield.h I don't recall any extraordinary changes to the libraries or calibration example to get the touchscreen working. The only thing I do recall, and it was fairly minor, was that the touchscreen on the 9486 was rotated 180 degrees to the 9341 I'd originally written the code for, so I added some code to figure out the rotation on the fly.
And while the link above references the 9341 shield, I put the sketch back into a handy Minima and plugged a 3.5 9486 shield into it, and it worked just fine.
Thank you for the prompt response, I appreciate it. Unfortunately, replacing the MCUFRIEND_kbv/utility/mcufriend_shield.h file with yours appears to have done nothing. Since mine is already a fork of the original, I believe it comes with R4 support. The same error message appears when I attempt to run a diagnosing program:
Not possible to diagnose Touch pins on ARM or ESP32
ID = 0x9486
I would just use an R3, but I wish to use the wifi functionality of the R4. Do you have any ideas on the matter?
Since you're using a fork of the original library, replacing the mcufriend_shield.h file was unlikely to have any affect. I simply pointed out what I'd done to make the original work.
I've already given you my ideas on the matter. I started with the original library and added R4 support to it and that works. What the problem is with the tutorial you're working with, I couldn't say. And I'm in no position to be able to offer any insights into a diagnostics program that you have not shown.
Thank you @van_der_decken for your help. Sorry about the lack of information, I am still quite new to this, and have a long way to go. I managed to figure out the issue. The error still persists, but I managed to find my way around the issue by using a different set of pins for touch. Again, thank you for all of your help, I appreciate it.