If your 5V DC-DC converter is reasonably clean, it should work OK to power the Teensy 4.1. I run the Teensy 4.1 on most of my boards directly from a DC-DC converter.
It is always best to power the Teensy 4.1 using 5V on the VIN/5V pin or you...
I have a new Teensy 4.1 board in the works that uses the 3.5" ST7796 IPS display with FT6336 capacitive touch. A really nice upgrade over the typical ILI9341 setup. Higher resolution, better viewing angles and no need to calibrate the touch...
Just to clarify, the parts that Adafruit sells are listed as generic and have the markings sanded off in their pictures. Their ESP datasheet is listed as a representative datasheet and they are probably not selling ESP brand parts now, though...
True, those round turned pins will work with a standard IC socket. I sell those pins myself for installing in small SMD to DIP adapter boards that are destined to be plugged into a standard IC socket and they work well for that.
I personally...
That one will work fine and is a higher quality part with gold plating. Didn't find it when I did a search. The JLCPCB search function tends to be a little clunky.
That socket will fit the Teensy pins OK.
The issue you would likely run into is that you usually can't butt two of these types of connectors together on 2.54mm centers because the housings have some tolerance on their overall length and are...
I can see your pictures and your soldering looks reasonable. Cleaning the flux off might help identify if there is a solder whisker somewhere that the flux is masking.
If you are getting 0.116V with the Teensy 4.1 no longer in the system and...
You have 8MB PSRAM and 256MB of NAND Flash that have been added to the bottom of the Teensy which sit on a QSPI bus. To have 16MB PSRAM, a 2nd 8MB PSRAM chip would be installed instead of the 256MB Flash chip. The Teensy 4.1 by itself does not...
The SPI on Teensy 4.1 works fine as demonstrated by thousands of successful implementations, my own included. It is also unlikely that you have a bad board. Actual bad Teensy boards out of the bag are very rare.
Doing a Google search on "Logic...
The FT5206 touch chip used on these displays has gone EOL. The new displays are starting to ship with the FT5316 touch chip that is suppose to be fully compatible per my communications with BuyDisplay.
I just tested one with the new FT5316...