Networking and communications

The purpose of the week is to fabricate the "hello" network example boards and program them

In link with my project i decided to add two board that can detect proximity or vibration .

Bridge Board

I rebuild this board from Neil's schematic:

Design
Trace CutOut

Node LED Board

I rebuild this board from Neil's schematic:

Design
Trace CutOut

Node IR proximity detection

I would like to detect proximity, I used the Neil's synchronous detection spread spectrum board but I need to detect proximity also on holds that are light off, so I can't use normal led. So based on the same schematic I replace the Led and the phototransistor by ones who work in Infrared spectrum. These 2 componants won't be directly on the board but replaced by a 2x2 PIN connector. The lED and the PhotoTransistor will be put inside the hold.

Design
Trace CutOut

Node Vibration board

I would like to detect vibration when some touch the hold, I decide tu use Piezo disk which transform vibration into electricity. As there is 2 Pin free I will connect 2 piezo by Tiny 45. Same as the other board, these 2 piezo won't be directly on the board but replaced by a 2x2 PIN connector. The piezo will be put on the backside of the hold.

Design
Trace

Network test

As I want to use the IDE envirronment, the I2C network for Tiny45 is not in the core lib so you will have to install the following library:
TinyWireS.h for the slave, TinyWireM.h for the master.

you can find those library github repository :github


Code for Nodes

Design
      


/* ATtiny45 as an I2C Slave   
 *

 * ATtiny Pin 1 = (RESET) N/U                      ATtiny Pin 2 = (D3) N/U
 * ATtiny Pin 3 = (D4) to LED1                     ATtiny Pin 4 = GND
 * ATtiny Pin 5 = I2C SDA                          ATtiny Pin 6 = N/U
 * ATtiny Pin 7 = I2C SCK                          ATtiny Pin 8 = VCC (2.7-5.5V)

 * More on TinyWireS usage - see TinyWireS.h
 */
#include "TinyWireS.h"                  // wrapper class for I2C slave routines

#define I2C_SLAVE_ADDR  0x10           // i2c slave address (16) ( 0x11 and 0x12 for the 2 others )
#define LED1_PIN         4              // ATtiny Pin 3


void setup(){
  pinMode(LED1_PIN,OUTPUT);             // lep pin
  Blink(LED1_PIN,1);                    // show it's alive
  TinyWireS.begin(I2C_SLAVE_ADDR);      // init I2C Slave mode
}
void loop(){
  byte byteRcvd = 0;
  if (TinyWireS.available()){           // got I2C input!
    byteRcvd = TinyWireS.receive();     // get the byte from master
    Blink(LED1_PIN,byteRcvd);           // master must wait for this to finish before calling Wire.requestFrom
                                       
                                        // send it back to master
    TinyWireS.send(byteRcvd);                 
  }
}

void Blink(byte led, byte times){ // poor man's display
  for (byte i=0; i< times; i++){
    digitalWrite(led,HIGH);
    delay (200);
    digitalWrite(led,LOW);
    delay (100);
  }
}

code for Bridge

      


/* ATtiny45 as an I2C Master 
 * I2C master
 * SETUP:
 * ATtiny Pin 1 = (RESET) N/U                  ATtiny Pin 2 = N/U
 * ATtiny Pin 3 = (D4) N/U                     ATtiny Pin 4 = GND
 * ATtiny Pin 5 = SDA                          ATtiny Pin 6 = N/U
 * ATtiny Pin 7 = SCK                          ATtiny Pin 8 = VCC (2.7-5.5V)
 * NOTE! - It's very important to use pullups on the SDA & SCL lines!

 * TinyWireM USAGE see TinyWireM.h   */

#include                   // I2C Master lib for ATTinys which use USI
#include 

#define NODE1_ADDR   0x10        // 7 bit I2C address node1
#define NODE2_ADDR   0x11        // 7 bit I2C address node2
#define NODE3_ADDR   0x12        // 7 bit I2C address node3
#define RX 3
#define TX 4
int datareceived = 0;
SoftwareSerial Myserial(RX,TX);

void setup(){
  Myserial.begin(9600);                 
  TinyWireM.begin();                    // initialize I2C lib
  delay (1000);
}

void loop(){
  delay(5000);
  Myserial.print("demande de blink node1");
  BlinkNode(NODE1_ADDR,0x1);
  datareceived = TinyWireM.receive();
  Myserial.println(datareceived);
  delay (1000);
  BlinkNode(NODE2_ADDR,0x2);
  delay (1000);
  BlinkNode(NODE3_ADDR,0x3);
  delay (1000);

}

void BlinkNode(byte NodeNum,byte times) 
{
  TinyWireM.beginTransmission(NodeNum);
  TinyWireM.send(times);                 // Ask node to blink n time
  TinyWireM.endTransmission();          // Send to the slave
}


According to Arduino.cc,dy default the I2C master library (TinyWireM) is set to run at 1MHz. To run at 8MHz, #defines in USI_TWI_Master.h / .cpp must be changed. No changes are necessary for the I2C slave library (TinyWireS). I have made the following changes in USI_TWI_Master.cpp:
#define F_CPU 8000000UL // was 1000000UL

I have made the following changes in USI_TWI_Master.h:
#define SYS_CLK 8000.0 // was 1000.0
#define T2_TWI 1.3 // was 5
#define T4_TWI 0.6 // was 4
But it was not working, Node slave blink 0ne times at power up but no communications between slaves and master. The Value for T2_TWI and T4_tWI have to be define using an oscilloscope I think. The fablab doesn't have an oscilloscope So I decided to use JMDuino board as master in order to use the Wire library instead of TinyWireM lib.
Design


// Wire Master Writer

// Refer to the "Wire Slave Receiver" 



#include 

#define NODE1_ADDR   0x10        // 7 bit I2C address node1
#define NODE2_ADDR   0x11        // 7 bit I2C address node2
#define NODE3_ADDR   0x12        // 7 bit I2C address node3

int datareceived = 0;

void setup()
{
  Serial.begin(9600);
  Wire.begin(); // join i2c bus (address optional for master)
}



void loop()
{
Serial.print("demande de 3 blinks a node1: ");
BlinkNode(NODE1_ADDR,3);
delay(3000);

Serial.print("demande de 5 blinks a node2: ");
BlinkNode(NODE2_ADDR,5);
delay(3000);
  
Serial.print("demande de 7 blinks a node3: ");
BlinkNode(NODE3_ADDR,7);
delay(3000);  
}

void BlinkNode(byte NodeNum,byte times)
{
Wire.beginTransmission(NodeNum); // transmit to device nodenum
Wire.write(times);
delay(1000);
//Wire.requestFrom(NodeNum,2);
//while (Wire.available())   // slave may send less than requested
//  {
//datareceived = Wire.read();
//Serial.print("reponse:");
//Serial.println(datareceived);
//  }
Wire.endTransmission(); 

}




Apparently it works but some loops after in the master program it seems that the synchronisation is lost. The debugging using serial.print doesn't help a lot. Without an oscilloscope I was not able to find the problem.

you can find the design files on my github repository :github