week-14

Understanding Networking and Communication

WEEK14: NETWORKING AND COMMUNICATION

ASSIGNMENTS:

Individual assignment

Design and build a wired &/or wireless network connecting at least two processors

Group assignment

Send a message between two projects

Last week we have learned how to establish connection and communication between Input and output device via interface, but with same processor/microcontroller or processor.
This week's objective is to send/receive data from input/output devices which is installed with two different micro-controllers.
For this to happen one multiple microcontrollers need to be connected as network.
After referring some of tutorial I understood that this communication between boards (micro controllers) can happen by Serial communication, I2C or SPI.
Very good tutorial to understand serial communication one can refer is sparkfun tutorial
One can start this with what are requirements to create such network to share data such as common communication protocol between boards.

STEP01: Exploring types of communication for micro controllers

Serial communication: Serial communication is interlinking circuits by means of sending/receiving data one bit at a time, ow hole bunch of data at a time (Parallel).
Very good tutorial can be found here from Sparkfun tutorial on serial communication

SERIAL PERIPHERAL INTERFACE(SPI) : Serial peripheral interface uses separate clock and data lines, along with a select line to choose the device you wish to talk to
Very good tutorial can be found here from Sparkfun tutorial on serial communication

INTER-INTEGRATED CIRCUIT(I2C) : I2C is somewhat same as SPI, but it can use multi-master and 1008 slave (circuit boards) to communicate with 2 wire.
Very good tutorial can be found here from Sparkfun tutorial on serial communication

STEP02: Defining application I want to do

As networking application I have decided to do task that, I will send signal by wireless from the application I have developed and pass that signal to 3 different boards.
So, for this week I am going to use which I have design and fabricated in week 7, and I will provide input signal from application which I have developed in week 13

STEP03: Program the boards for Serial communication

Now in order to send data by serial communication, I have to program my boards separately, and upload the code individually.
In both the codes my variables will remain same but the value will be changed.
So, I started with defining Rx pin with pin number 2 of my board. And set mySerial with Rx and Tx pins.
After that I store value of character 'a' as number 1, and wrote the if else loop to perform required task or here to make LED low and high.

#include <SoftwareSerial.h>

#define RxD 2

#define TxD 0

#define DEBUG_ENABLED 1

#define LED_A 4

SoftwareSerial mySerial(RxD,TxD);

void setup() {

pinMode(RxD, INPUT);

pinMode(TxD, OUTPUT);

mySerial.begin(9600);

pinMode(LED_A,OUTPUT);

}

void loop() {

if(mySerial.available()>0)

{

int a = mySerial.read();

if (a == 1)

{

digitalWrite(LED_A,HIGH);

}

else

{

digitalWrite(LED_A,LOW);

}}}

Program for another board will remain almost same with change in LED value low and high under

#include <SoftwareSerial.h>

#define RxD 2

#define TxD 0

#define DEBUG_ENABLED 1

#define LED_A 4

SoftwareSerial mySerial(RxD,TxD);

void setup() {

pinMode(RxD, INPUT);

pinMode(TxD, OUTPUT);

mySerial.begin(9600);

pinMode(LED_A,OUTPUT);

}

void loop() {

if(mySerial.available()>0)

{

int a = mySerial.read();

if (a == 0)

{

digitalWrite(LED_A,HIGH);

}

else

{

digitalWrite(LED_A,LOW);

}}}

STEP05: Wiring connection for serial network

After uploading code in boards by FabISP, I have made wiring connection between boards by serial bus.
I have used two FTDI cables to supply power to boards and bluetooth module.
VCC, GND and SCK (Rx) connections are in common serial.

STEP05: Test network communication between boards

Once boards are ready I have connected them in above pattern along with bluetooth module.
Also I have powered up boards and bluetooth by separate FTDI cables.

Once powered up, I have tested the network communication with application which I have developed in week 13.
In below video working functionality can be tested as all boards in network.

COMMUNICATION BETWEEN BOARDS WITH ADDRESS CODE

In order to make communication between my boards, I have used one master and two slave board. Whereas my master board will send digital data by means of switch i.e. High and Low.
For communication I have taken reference from Jari Uusitalo, who has used node to transmit and receive data, by closing Rx channel in nodes by turning it into input
Basically here, communication happens by sending specific call to particular addressed board, and that replies back accordingly.

Master board program

For programming master board I have used below code with input as switch and using SCK of master board as Tx pin. Here I am addressing board with character 1 and 2.

#define B

#include<SoftwareSerial.h>

SoftwareSerial ms(1,2); // rx , tx

void setup()

{

pinMode(2,OUTPUT);

pinMode(1,INPUT);

pinMode(4,OUTPUT);

pinMode(B,INPUT);

ms.begin(9600);

}

void loop()

{

if( digitalRead(B) == LOW)

{

digitalWrite(4,HIGH);

//digitalWrite(1,LOW);

ms.write('1');

}

else if( digitalRead(B) == HIGH)

{

digitalWrite(4,LOW);

ms.write('2');

}

Slave board 1 program

For programming Slave board 1, I have used below code by addressing value of board as character 1, and transmitting signal by SCK pin and receiving from MISO pin.

#include <SoftwareSerial.h>

SoftwareSerial mySerial(1, 1); // RX, TX

int node = '1'; // network address

const int ledPin1 = 4;

int incomingByte;

void setup() {

mySerial.begin(9600);

pinMode(ledPin1, OUTPUT);

pinMode(1, INPUT);

}

void loop() {

if (mySerial.available() > 0)

{

incomingByte = mySerial.read();

if (incomingByte == node)

{

digitalWrite(ledPin1, HIGH);

pinMode(1, OUTPUT); // open line to write

mySerial.println(node);

pinMode(1, INPUT);

}

else

{

digitalWrite(ledPin1, LOW);

}

}}

Slave board 2 program

Programming second slave board is just same as above, just the addressing of this board will change to character 2.

#include <SoftwareSerial.h>

SoftwareSerial mySerial(1, 1); // RX, TX

int node = '2'; // network address

const int ledPin1 = 4;

int incomingByte;

void setup() {

mySerial.begin(9600);

pinMode(ledPin1, OUTPUT);

pinMode(2, INPUT);

}

void loop() {

if (mySerial.available() > 0)

{

incomingByte = mySerial.read();

if (incomingByte == node)

{

digitalWrite(ledPin1, HIGH;

pinMode(2, OUTPUT); // open line to write

mySerial.println(node);

pinMode(2, INPUT);

}

else

{

digitalWrite(ledPin1, LOW);

}

}}

Communication Test

Once programs have been uploaded successfully in Master and Slave board, I have checked functionality of communication as below by connecting boards as shown in wiring diagram.
Here I have used board network connection hub made by fellow fab academy student Adhitya and designed by Jari Uusitalo

In below video communication between board can be seen as master board input is given by switch. Also the values of responsive communication can be seen in serial monitor

ORIGINAL FILES

I am attaching here original files for this week as package, which includes program files which I have used for network communication.
This can be downloaded from here

INDIVIDUAL CONTRIBUTION TO GROUP WORK

For this week's group work we have decided to establish communication between two board, and use IR sensor as input device.
As board we have used fellow fab academy students' board. I played major role in programming these board for communication.
For programming I have used serial communication over two board as pin number 8 and 9 I used as input and output.

Click here for documentation on communication over two project on lab website

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2018 | Tanvir Khorajiya