Master Receive Data from Arduino UNO

Materials

• AMB82-mini x 1

• Arduino UNO x 1

Example

I2C Introduction

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.

Introduction

In the 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 master, and receives data from the Arduino UNO, which is the I2C slave.

Procedure

• Setting up Arduino Uno to be I2C Slave

First, select Arduino in the Arduino IDE in “Tools” -> “Board” -> “Arduino Uno”:

Open “Examples” -> “Wire” -> “slave_sender”

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

• Setting up Ameba to be I2C Master

Next, open another window of Arduino IDE, make sure to choose your Ameba development board in the IDE: “Tools” -> “Board”

Open “File” -> “Examples” -> “AmebaWire” -> “MasterReceiveData”

Click “Sketch” -> “Upload” to compile and upload the example to Ameba.

• Wiring

The Arduino example uses A4 as the I2C SDA and A5 as the I2C SCL.

Another important thing is that the GND pins of Arduino and Ameba should be connected to each other.

AMB82 MINI wiring diagram:

Next, we will observe the data receive by Ameba in the Serial Monitor.

(Note: If you do not know which port the Ameba development board is connected to, please find it in the Device Manager of Windows first. Ameba is connected as “mbed Serial Port”. For example, if you find mbed Serial Port (COM15) means Ameba is connected to port COM15.)

We select the port in “Tools” -> “Port” -> “COM15” (the port connected to Ameba)

Open the Arduino IDE window of the Ameba, go to “Tools” -> “Serial Monitor” to display the messages printed by Ameba.

Press the reset button on Arduino Uno, Arduino Uno now waits for connection from I2C master.

Then press the reset button on Ameba, Ameba will start to receive messages from Arduino Uno. And you can see the “hello” message printed every half second in serial monitor.

(NOTE: If the message does not show in the Serial Monitor of Ameba, please close and open the serial monitor again.)

Code Reference

You can find detailed information of this example in the documentation of Arduino:

https://www.arduino.cc/en/Tutorial/MasterReader

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.

https://www.arduino.cc/en/Reference/WireBegin

Next, the Master uses Wire.requestFrom() to specify from which Slave to request data.

https://www.arduino.cc/en/Reference/WireRequestFrom