Michael VE3WMB brings us some hints when installing Nextion displays:
1) The Display wants the microSD card to be formatted as FAT32. Make sure your microSD card is no larger than 32GB
The default in Windows is to format cards > 32 GB as exFAT, which the Nextion will not accept. In fact Windows 10 probably won’t even let your reformat a card this big as FAT32. (I am sure if you dig deep enough there might be a way to do this. I am not a Windows GURU).
Currently you only need a 2 GB card, so if you need to buy one for this purpose try an 8GB card. It is also worthwhile buyong a brand name card (like Sandisk).
Some no-name cards are slower than cold molasses to read from and write to.
2) If you have a problematic microSD card, when you power up the rig you might not see anything on the display, not even a backlight !
I spent considerable time trying to solve what I thought was a wiring/power problem to the display when it was a bad SD card. When the I removed the card and power-cycled the rig the Nextion display came up fine with a demo program that was already loaded. So my recommendation is for the initial power up of the display don’t insert the SD card. That way you can be sure that you have it wired up ok before you start messing with SD cards.
3) Beware, ground and +5V connections on the Raduino going to the Nextion Display are adjacent to each other.
I recommend that you check and recheck your wiring several times before applying power. It is very easy to accidentally swap these and you won’t be happy if you do. As they say, “An ounce of prevention is worth a pound of cure”. One group member has already found this out the hard way.
Mark AA7TA adds:
4) Duplicate .tft files (including hidden files) will cause grief on the Nextion
You may get a message on the display that the load failed because there is more than one .tft file on the SD card. This can happen even when you look and you see only one file.
You need to be sure to enable viewing of hidden files in file explorer (Windows) or finder (on a Mac)… There’s probably one hiding there with the .tft suffix that you need to delete. I don’t think either operating system will show hidden files by default. The same goes for Linux.
Mark notes that a 1G SD card is plenty big enough for the current tft file.
Keven adds, “Linux doesn’t show hidden files by default. But you can see them by typing:
in a terminal window when you’re in the directory you want to examine. To hide a file, rename it with a dot (‘.’) as the first character.”
Mike ZL1AXG adds:
5) Make sure you install the screen the right way around
Power up the display before you start making holes and check the orientation of the display and that the screen is functioning correctly. As with the 16×2 display, it is possible to install the display upside down by mistake! Given it is not symmetric (there is a wider bar to the right hand side of the display) care is needed! The inner silver line on the screen defines the touch sensitive boundary. Cut your hole so that the screen fits so the line is just visible around the outside edge.
Dimensions of Nextion displays can be found for this zone on the itead website. Click on your display and near the bottom of the page you will find a link to the screen dimensions.
6) For most people the 3.2″ screen or larger will be best
A 3.2″ screen is only just big enough to feel comfortable for us fat-fingered chaps. It is also just wider enough to reuse the width of the 16×2 screen. Smaller screens inserted in the space where the 16×2 screen currently lives will require an additional aluminium or plastic plate to be added to the front panel to cover the existing width of the 16×2 screen.