The TagConnect connector follows my own standard which I've created for my devices using an ESP8266. The device should utilize this pinout: Whereas TXD goes to the TXD of the ESP8266 and RXD goes to ...

There is a 5V and a 3,3V regulator on the board that supplies the ESP8266 and the Logic of the display modules ... The Display Modules can be attached via the 2.4mm Pinheader on the edge of the board.