The library comes with examples (just scroll down or hit the GitHub icon) and the pins to use are Vin, GND, RX, TX.
One odd thing with the examples is that an immediate build seems to fail.
After a short while or a minor change (e.g. #include "Nextion.h" to #include <Nextion.h>) building usually works - no clue why that is.
Unfortunately this early release version of the lib doesn’t allow for easy use of these, but I’ll implement a workaround soon.
My original endeavour to wrap this in a proper C++ library got stalled by other things, but with that you should be able to even use ParticleSoftSerial.
Meanwhile you may be able to move your max3232 to one of the alternative interfaces or have to wait for my workaround.
I think I have to try this myself then.
I’ll report back when I know more.
BTW, if you power the Electron via USB you can power the display off Vin & GND.
But if you need a seperate power supply, make sure to have the Electron’s GND tied to the common ground level.
@ScruffR
I have tried to power up the Display via the Vin & GND from Electron, it looks like it do not have much power for a 5" display.
Okay super @MegZamani - i did tied Electron’s GND at the same point, as the external power supply GND.
Yes… All my power to the circuit should have a common ground.
So the frist test with serial --> (Particle Electron Tx-Rx) to display - WORKING
2nd test - nexSerial Serial4 on Electron ( C3[TX] & C2[RX] )
As it seems the build sequence causes the #define nexSerial Serial4 line to be ignored when compiling the library modules.
So I’ll have to go the long way round to support alternative interfaces.