I2C - Slave Receive Data from Arduino UNO



There are two roles in the operation of I2C, one is “master”, the other is “slave”. Only one master is allowed and can be connected to many slaves. Each slave has its unique address, which is used in the communication between master and the slave. I2C uses two pins, one is for data transmission (SDA), the other is for the clock (SCL). Master uses the SCL to inform slave of the upcoming data transmission, and the data is transmitted through SDA. The I2C example was named “Wire” in the Arduino example.

In the previous example “I2C – Send Data to Arduino UNO” , Ameba, the I2C master, transmits data to the Arduino UNO, the I2C slave. As to this example, Ameba is the I2C slave, and receives data from the Arduino UNO, which is the I2C master.

  • Setting up Arduino Uno to be I2C Master

First, select Arduino in the Arduino IDE in “Tools” -> “Board” -> “Arduino Uno”:
Open “Examples” -> “Wire” -> “master_writer”


Then click “Sketch” -> “Upload” to compile and upload the example to Arduino Uno.

  • Setting up Ameba to be I2C Slave

Next, open another window of Arduino IDE, making sure to choose your Ameba development board in the IDE: “Tools” -> “Board”
Open “File” -> “Examples” -> “AmebaWire” -> “SlaveReader”

  • Wiring

The Arduino example uses A4 as the I2C SDA and A5 as the I2C SCL.
Another important thing to note is that the GND pins of Arduino and Ameba should be connected to each other.

Open the Arduino IDE of the Arduino Uno and open the serial monitor (“Tools” -> “Serial Monitor”).
Next, press the reset button on Arduino Uno. Now the Arduino Uno (Master) is establishing connection to Ameba (Slave). In the Serial Monitor, you can see the messages printed from Arduino Uno.
We press the reset button on Ameba to start receiving messages from Arduino UNO. Then observe the serial monitor, you can see the messages show up every 0.5 second.


Code Reference

You can find detailed information of this example in the documentation of Arduino:
First use Wire.begin()/Wire.begin(address) to join the I2C bus as a master or slave, in the Master case the address is not required.
Next, the Master uses Wire.beginTransmission(address) to begin a transmission to the I2C slave with the given address:
Uses Wire.write() to send data, and finally use Wire.endTransmission() to end a transmission to a Slave and transmits the bytes that were queued:
Please confirm that QQ communication software is installed