I recently started learning IoT with ESP8266MOD (Arduino IDE). I want to start working with Google Cloud IoT, but confused about how to use google-cloud-iot-arduino.

I tried its Esp8266-http example, but it gives error:

fatal error: String.h: No such file or directory

Edit -

I already setup Arduino IDE to use with ESP8266, and Test with Demo Blink, it working fine. Now I've next task, connect ESP8266 to Google Cloud Iot.

  1. Using mongoose os, which have easy procedure. (I successfully connect to Iot Core).

but there is no Library available for MFRC522

  1. Using google-cloud-iot-arduino example, but it give error
    Error: 'NN_DIGIT' does not name a type and also Library like String.h not Found.

Arduino IDE Version is 1.8.5.


1 Answer 1


The title of your question has one issue, but the text of your message has another...you might want to either change the title, or create a new question ;)

As for the error in your text: Is this error happening when you try to compile your sketch in the Arduino IDE? The error points to a missing module or library, which the author of the google-cloud-iot-arduino assumed you would already have. Have you used your ESP8266 board before, or is this the first time using one? If so, you might want to start out with something a little more simple just to make sure things are working correctly. For example, here is a link to the Adafruit tutorial for their ESP8266 breakout board that shows what you need to do in order to program the board: https://learn.adafruit.com/adafruit-huzzah-esp8266-breakout/using-arduino-ide


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