setup arduino IDE for ESP8266

download the latest Arduino IDE and unpack it.
create a subdirectory called portable
start your arduino IDE and go to File→preferences and add this to Additional Boards Manger URLs: http://arduino.esp8266.com/stable/package_esp8266com_index.json
select OK and go to Tools-Boards…-Boards Manager… and enter ESP into the search. now install the esp8266 module and close that window.

for generic ESP boards verify your settings under Tools are like these:

Board: "Generic ESP8266 Module"  <<<<!!!!
Flash Mode: "DOUT"  <<<<!!!!
Flash Size: "1M (no SPIFFS)"  <<<<!!!!
Debug Port: "Disabled"
Debug Level: "None"
LwIP Variant: "v1.4 Prebuilt" <<<<!!!
Reset Method: "ck"
Crystal Frequency: "26 MHz"
Flash Frequency: "40MHz"
Upload Using: "Serial"
CPU Frequency: "80 MHz"
Upload Speed: "115200"
Port: Your COM port connected to sonoff

for the Wimos D1 mini boards I used these settings (despite mine was called D1 mini and there is also a board setting for the mini, but it didn't upload the sketch when it got bigger than a very small size):
```
Board: "Wemos D1 R2"
Flash Size: "4M (1M SPIFFS)"
```
leave the rest to the defaults