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I'm newbie in Arduino programming so I hope to get a clear answer.

I have NodeMCU v1 12-E, I connected it with RFID RC522 as in attachment picture.

Now my question:
I need to connect I2C interface LCD module with it to print some words in.
The RFID use the default SDA and SCL pins on NodeMCU V1.0 "D1 and D2" also when I see wiring for the LCD I2C it use same D1 and D2 pins.
So now if I change the RFID instance creation code to

MFRC522 mfrc522(0,2); 


Is the RFID will work as previous pins and the LCD will work also?

  • this is will not work in I2C bus just go with the UART protocol this will work perfectly and its communication is very easy – deepak Nov 1 '18 at 11:24

You can have multiple devices on the I2C bus so long as they all have different addresses. This means you should be able to connect D1 and D2 to the RFID and LCD. HOWEVER I'm not sure that you are using I2C to talk to the RFID board, if you aren't then you may need to move the RFID boards pins and leave I2C on D1&2.

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  • Thank you for reply Code Gorilla, I tried to change i2c to d3 and d4 for RFID, and the default d1 and d2 for I2C lcd module. they worked perfectly together. – Ameen May 11 '17 at 21:28

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