Milkcocoa is a cloud-based platform which enable us to exchange data in real time, its service is provided by Uhuru Technical Rockstars.

Let’s go through a tutorial for Milkcocoa. For this tutorial, we will put a GR board and ESP8266 Wi-Fi module together.



Connect it with a WA-MIKAN board which can be purchased at Akizukidenshi.com.

ESP8266 modules can be used with the same example program.



You will want to get the ESP8266 module ready and connect TX and RX signals for serial communication. The example connected to GR-SAKURA is as follows. Set IO15 pin at Low, EN pin at High, since the ESP8266 is used with an AT command mode.


Creating the Application with Milkcocoa

Log in and create the application to use the Milkcocoa service. Be sure to check out the Milkcocoa Tutorial for some helpful tips.

1. Login

Please note that it is necessary to create an account to login.


2. Creating an Application

Push the button to create an application with a suitable name. The image to the right shows the application named "GR".


3. Copy of app_id

The application overview is displayed when the created application is clicked. Cloud access will be gained based on the information of this screen. Don’t forget to copy the "app_id" for later use.


Access to Milkcocoa

Making a Project

With the library to access Milkcocoa in the template on the web compiler, let’s make a project.


Editing the Sketch Program

Open gr_sketch.cpp and edit four shown below. Then, let’s build and write cotton_sketch.bin at GR-COTTON.

  • ESP_Serial: Serial communication number, refer to the pin map.
  • WLAN_SSID: Access point SSID
  • WLAN_PASS: Password at the access point
  • MILKCOCOA_APP_ID: The app_id for the application created with Milkcocoa
  • MILKCOCOA_DATASTORE: Suitable element name, temporarily MILK_COTTON here

Operation Check

After writing the sketch program, let’s check it with serial monitors such as Teraterm. In the case of GR-SAKURA and/or GR-CITRUS, please note that sometimes it may not start unless you press the enter key on your keyboard after the monitor starts. Please find the successful example of the access to Milkcocoa in the image to the right, 「onpush」and/or「v:**」displayed in the end of display.

In this case, the GR board send out temperature data to Milkcocoa every seven seconds and then displayed them in the monitor when a notice came from Milkcocoa. It means, if several GR boards connect to Milkcocoa, they can receive notices at the same time.


Let’s check the Milkcocoa datastore to see it uploading {"v":**} every seven seconds.


Let’s Try to Operate the GR Board on a Web Browser

Please refer to an example of an operating GR board through a web browser on the GR-COTTON Special Project: Cloud Access with Milkcocoa! page.