I2C - Receive Data from Arduino UNO

Materials

  • AmebaD [AMB21 / AMB22 / AMB23 / AMB25 / AMB26 / BW16 / AW-CU488 Thing Plus] x 1

  • Arduino UNO x 1

Example

Introduction

In the previous example “I2C - Communicate with Arduino UNO via I2C”, Ameba, the I2C master, transmits data to the Arduino UNO, the I2C slave. Whereas in 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”

image01

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” → “MasterReader”

image02

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.

AMB25 Wiring Diagram:

image08

Next, we will observe the data received 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), that means Ameba is connected to port COM15.

image10

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.

image11

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