A mini wifi board with 4MB flash based on ESP-8266EX.
Install the ESP8266 Board Manager
We’re going to add a new bunch of boards into the Arduino IDE board manager, as the Wemos isn’t in there by default.
In the Arduino IDE, go to File > Preferences. A window will pop up, and at the bottom is a field called ‘Additional Boards Manager URLs‘.
Simply copy and paste the following into that field, then press OK:
Install the ESP8266 Library
Now we need to install the library for our Wemos.
Go to Sketch > Include Library > Manage Libraries, then in the search box enter ‘ESP8266 Platform‘.
Connect & Select the Wemos
Plug your Wemos in to a USB port on your PC (make sure it’s a proper data cable, and not some nasty power-only crapper).
Now we need to tell the Arduino IDE which board we’re using. Select Tools > Boards > WeMos D1 R2 & Mini.
You’ll notice a load of new options appear such as ‘Flash Size’, ‘CPU Frequency’, ‘Upload Speed’ etc – ignore all of these (for the Wemos D1 mini at least). All you need to do is ensure your Wemos COM port is selected
Load the Blink Sketch
We’re going to upload the mighty ‘blink’ sketch to test that the Wemos is talking to everything properly, and is able to accept a sketch.
The Wemos D1 Mini has an on-board LED (trust me, it’s there) so no components are required here.
Load the blink sketch by selecting File > Examples > ESP8266 > Blink. The IDE window should load something like this: