Where is the user manual? Not for the editor, but for connecting with/to the Nextion board?
I assume at this point that the RX and TX are RS232. Is it TTL level?
If I missed the manual, please point me in the right direction.
I also hope ITEAD will soon release a user manual.
Until then you can use information from the Nextion Wiki:
According to the datasheet, RX/TX are TLL level: