Assignments

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

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Designing schematic & board layout

I have decided to use I2C communication to communicate between two attiny45 based boards.

I have interfaced switch to one attiny 45 board (Slave board)& led to another attiny45 board (Master board). When a switch will be pressed on slave board, it will communicate the same to master board through I2c & accorduingly LED on master board will glow.

Here is the schematic & board layout designed in eagle for both the boards.

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Milling & Soldering the board

Then I milled the board & soldered it.

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Embedded Programming

Here is the master code.

/* Master code */
#include "TinyWireM.h"
#define device (1)
int ledPin = 4;

void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);
  TinyWireM.begin();
  delay(1000);
}
void loop() {
  if(IsSwitchPressed(0x1)==1)
  {
    digitalWrite(ledPin, LOW);
  } 
  else if(IsSwitchPressed(0x1)==0)
  {
    digitalWrite(ledPin, HIGH);
  }
}

int IsSwitchPressed(uint8_t slaveAddress){
   int Output = 0;
   TinyWireM.beginTransmission(slaveAddress);
   TinyWireM.requestFrom(slaveAddress, 1);
    Output = TinyWireM.receive();
    return Output;
}
	

Here is the slave code.

/* Slave code */	
const int buttonPin = 3;
int switchcondition;
int buttonState = 0;
#define I2C_SLAVE_ADDRESS 0x1 

#include "TinyWireS.h"

#ifndef TWI_RX_BUFFER_SIZE
#define TWI_RX_BUFFER_SIZE ( 16 )
#endif

volatile uint8_t i2c_regs[] =
{
    0xDE, 
    0xAD, 
    0xBE, 
    0xEF, 
};

volatile byte reg_position;
const byte reg_size = sizeof(i2c_regs);

void requestEvent()
{  
    TinyWireS.send(CheckSwitchCondition());
    // Increment the reg position on each read, and loop back to zero
    /*
    reg_position++;
    if (reg_position >= reg_size)
    {
        reg_position = 0;
    }*/
}



void setup() {
  // put your setup code here, to run once:
  pinMode(buttonPin, INPUT); // Sets the buttonPin as an Input

  TinyWireS.begin(I2C_SLAVE_ADDRESS);
  TinyWireS.onRequest(requestEvent);
  
}

void loop() {
  // put your main code here, to run repeatedly:

  TinyWireS_stop_check();
}


int CheckSwitchCondition(){
  buttonState = digitalRead(buttonPin);
  if (buttonState == HIGH) 
  {
    switchcondition=1;
  }
  else
  {
   switchcondition=0; 
  }
  return switchcondition;
}
	

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Output Video

Here is the output...

networking_I2C from Chaitali Choudhary on Vimeo.

You can download files here...

• slave.sch
• slave.brd
• slave.jpg
• master.sch
• master.brd
• master.jpg
• masterProgram.ino
• slaveProgram.ino

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