I am coding furiously at/with/against/around my Nextion device, connected to a Due; and at present I'm doing this the safe-but-dumb way. Using the ITEAD GUI editor for Nextion, I do some design and embedded coding; compile the HMI file to make a TFT file; write the TFT file to a micro-sd card; power off the Nextion; shove the usd card into the nexti's dedicated usd card slot; power on the Nextion; wait... wait... wait for over a minute as it slowly loads the tft file and finally says, with charming ESLism, "Update Successed!" Rinse, repeat.
This gets old fast, especially when you gotta fix just one silly typo. So, there's another way to shove the TFT file at the Nextion unit. You can use a USB adapter to connect the nexti's serial lines to a usb port on the PC running the editor s/ware. The editor then recognises the device and can flash it over the USB port... quite a bit faster, or so I hear.
OK, sounds good, but that would mean... plug nexti tx/rx into the adapter, plug adapter into a USB port on the host PC, do editing, flash the Nextion, disconnect all the wires, reconnect tx/rx to the Arduino... ugh. The uSD card shuffle starts to look good by comparison!
So... it occurred to me to wonder whether I might enlist a second arduino, a lowly Uno or something, to switch those signal lines from one conformation to another... but the ordinary i2c digital mux is not really the right critter for the job. There are of course physical switches (USB A/B switches) out there, so I guess I could just hack one of those to be normal USB through on one side, and whatever tx/rx magic is required to go to the duino on the other side.
What clever solutions have other people come up with, if any, for switching a flashable device back and forth between a PC-based IDE and a duino deployment/test?