Wemos Mega is Arduino Mega compatible board plus additional ESP8266 with 32Mb Flash. It allows flexible configurations for connections between ATmega2560, ESP8266 and USB serial. Arduino sketches can be uploaded to ATmega2560 or ESP8266 via USB separately and they can either work together to form a system or independently. The configurations are set by the onboard DIP switch.
The onboard ESP8266 is pre-flashed with latest NodeMCU firmware, while it can also be flashed with any other ESP8266 firmwares like ESP8266 AT command-set firmware or uploaded with Arduino IDE for any Arduino sketches written for ESP8266.
DIP Switch Configurations
|USB<->ESP8266 (Update firmware or sketch)||OFF||OFF||OFF||OFF||ON||ON||ON|
An additional switch configures which serial UART (Serial0 or Serial3) that ESP8266 is connected to. It is possible to connect USB to RX0/TX0 of ATmega2560 and ESP8266 connects to RX3/TX3 of ATmega2560 at the same time, as following.
|USB <-> ATmega2560<-> ESP8266||ON||ON||ON||ON||OFF||OFF||OFF||To RXD3/TXD3|
1 x Wemos® Mega +WiFi R3 ATmega2560+ESP8266 32Mb Memory