15. Networking and communications

In this week I'll try two methods of communication between two nodes, which are the serial bus and the I2C communication protocol. For the group assignment, we will connect two projects together to send messages between them.

Softwares used:

Resources:

This week assignment content:

15.1. Group assignment.

15.1.1. Send a message between two projects.

For this week the group assignment is to send a message between two projects. Click here to enter the group assignment page.

15.2. Individual assignment.

Design, build, and connect wired or wireless node(s) with network or bus addresses.

15.2.1. Serial Bus (Arduino UNO + ATtiny44)

In this example I will connect Arduino UNO to my ATtiny44 board that I have created previously in week 7 and communicate with them trough serial bus. Steps are explained in details below:

15.2.1.1. Step 1: Set Arduino UNO as a programmer:

15.2.1.2. Step 2: Program the ATtiny44 board:

15.2.1.3. Step 3: Program the Ardunio UNO board:

15.2.1.4. Step 4: Serial monitor:

15.2.1.5. Problem faced:

Both LEDs on Arduino UNO and ATtiny44 didn’t work because I have connected ATtiny44 Tx pin to Ardunio Rx pin and vice versa. I didn’t get an error message, but there were no physical results as well as no output on the serial monitor.

15.2.2. I2C (Arduino UNO + ATtiny44)

My second try for this week assignment is using I2C communication protocol. It stands for Inter-Integrated Circuit. Also it's called 2-Wire Communication. In I2C, data are transmitted between devices using Serial Data Line (SDA) and Serial Clock Line (SCL). It can support the communication between multiple masters and multiple slaves devices at the same time.

To do the second test using I2C serial communication, I have used my ATtiny44 board that I have created before as a master board and Arduino UNO as the slave board for my program. Steps are explained below:

15.2.2.1. Step 1: Set Arduino UNO as a programmer:

First I set Arduino UNO as the programmer for my ATtiny44 board as explained previously in Serial Bus step 1.

15.2.2.2. Step 2: Add the ATtiny44Core board library:

To run the code, I need to install the ATtinyCore library. To do that, add the following URL to the board manager "Additional Boards Manager URLs" list.

http://drazzy.com/package_drazzy.com_index.json

15.2.2.3. Step 3: Program the ATtiny44 board (Master):

Then connect the ATtiny44 board ISP connector to Arduino UNO as mentioned previously in Serial Bus step 2. Upload the following code, which tells the program to send "1" through I2C serial wire when the push button (connected to pin PA2) is pressed.

#include <Wire.h>
#define button PA2
void setup() {
Wire.begin();
pinMode(button, INPUT);
}
void loop() {
int data;
data = digitalRead(button);
if (data == 1)
{
Wire.beginTransmission(8);
Wire.write(1);
Wire.endTransmission();
}
else {
Wire.beginTransmission(8);
Wire.write(0);
Wire.endTransmission();
}
}

15.2.2.4. Step 4: Program the Ardunio UNO (Slave):

Upload the following code to the slave board, which tells the program to send a high signal to pin 13 (LED) of the slave board.

#include <Wire.h>
#define led 13
void setup() {
Wire.begin(8);
Wire.onReceive(receiveEvent);
pinMode(led, OUTPUT);
}
void loop() {
delay(100);
}
void receiveEvent(int howMany) {
int x = Wire.read();
if (x == 1)
{
digitalWrite(led, HIGH);
}
if (x == 0)
{
digitalWrite(led, LOW);
}
}

15.2.2.5. Step 5: I2C connection:

Connect the two boards as the following configuration:

Note:
Blue line is SCL
Green line is SDA

15.2.2.6. Final result:

15.2.2.7. Problem faced:

If the ATtiny44 core library is not installed correctly, the following error message will appear:

15.2.3. I2C (ATtiny84 + ATtiny44)

My third try was using the same method of communication in the second try, which is I2C. But using ATtiny84 micro-controller board that I made for final project instead of Arduino UNO as the salve board.

15.2.3.1. Step 1: Set Arduino UNO as a programmer:

First I set Arduino UNO as programmer as explained previously in Serial Bus step 1.

15.2.3.2. Step 2: Program the ATtiny44 board (master):

Connect ATtiny44 board to Arduino UNO through ISP connector as mentioned in Serial Bus step 2. Set your Board option to ATtiny44, Clock to external 20 MHz, and choose the correct Port.

Connection:

Upload the same code that was uploaded in I2C step 3. Which tells the program to send "1" through I2C serial wire when the push button (connected to pin PA2) is pressed.

Code:

#include <Wire.h>
#define button PA2
void setup() {
Wire.begin();
pinMode(button, INPUT);
}
void loop() {
int data;
data = digitalRead(button);
if (data == 1)
{
Wire.beginTransmission(8);
Wire.write(1);
Wire.endTransmission();
}
else {
Wire.beginTransmission(8);
Wire.write(0);
Wire.endTransmission();
}
}

15.2.3.3. Step 3: Program the ATtiny84 (Slave):

Connect ATtiny84 board to Arduino UNO through ISP connector as mentioned before. Upload the following code to the slave board, which tells the program to send a high signal to PA2 (LED) of the slave board.

Connection:

Code:

#include <Wire.h>
void setup() {
Wire.begin(8);
Wire.onReceive(receiveEvent);
pinMode(PA2, OUTPUT);
}
void loop() {
delay(100);
}
void receiveEvent(int howMany) {
int x = Wire.read();
if (x == 1)
{
digitalWrite(PA2, HIGH);
}
if (x == 0)
{
digitalWrite(PA2, LOW);
}
}

15.2.3.4. Step 4: I2C connection:

Connect the two boards, which are the ATtiny84 and ATtin44 boards as explained previously in 15.2.2.5. Step 5: I2C connection. and observe that the LED that connected to ATtiny84 will be ON when the push button on the attiny44 board is pressed.

15.2.3.5. Final result:

15.2.3.6. Problem faced:

When I was trying to upload ArduinoISP code to Arduino UNO, I got an error and the code won't uploaded.

To solve this problem, I have used another Arduino UNO to burn bootloader of my Arduino UNO. Connection between the two Arduino UNOs is shown below:

After burning bootloader successfully, the following message will be shown and you can use the Arduino UNO again.