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Can I change the pins on the communication for a Master-Slave arduino Wire transmission? I want to communicate between 2 arduinos, but on one of them A4&A5 are taken

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up vote 4 down vote accepted

You cannot. Wire uses hardware I2C, and on the Uno only A4 and A5 are connected to the TWI peripheral on the MCU. You will need to either switch to a bit-bang I2C implementation or change the protocol you're using.

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To complete Ignacio's answer, there's indeed no other hardware I2C on AVR Arduinos.

The only options you have to use other pins is:

  • to use bitbang i2c, which is way slower ;
  • or you can switch to the Arduino Due which features two TWI ports ;
  • or you can use an SPI to I2C serial bridge such has that one.
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