All over bar the groaning..

Well, that's that for another year (academically speaking), but this blog will continue..

Last two projects were a bit of a frost - got most of the Minor Project posted, but i suspect hardware & programming logic problems, as i couldn't get it to do what i thought it should - it kept doing what i actually had told it to do.

As a poster i once saw says:

*                   I Know You Believe You Understood

*                 What It Was That You Though I Said,

*                          But I'm Not Sure You Realise

*                  That What You Thought You Heard

*                             Was NOT What I Meant!!

i can hear my Arduino chortling away at that thought, since it seems to me that what i thought i'd told it to do was something other than what i wanted {sigh}..

Always assuming the hardware works as expected, of course..

Projects -- Interrupts: Mark II

/*
 * Project:      Project_interrupt
 * Author:      Jane-Maree Howard
 * Date:         Monday 21/11/2011
 * Platform:    Arduino 22
 * Purpose:    To demonstrate an interrupt on Digital pin 3
 * Operation:  Description: Connect a 20kilOhm resistor from
 *                          digital pin3 to digital pin13!
 *                          Earlier problem solved as we now have a hardware feedback
 *                          from OUTPUT digi-pin13 to INPUT digi-pin3,
 *                          to which the interrupt is attached.
 *                          The digital flip-flop occurs every second, is fed to digi-pin3,
 *                          which registers the change & triggers the interrupt,
 *                          which, in turn, calls blink() where the pin state variable is flipped.
 *                          This state change is fed back via digi-pin13 to digi-pin3, triggering
 *                          the interrupt once again.                 
 */
int           iPin13   = 13;
int            iPin3   = 3;
volatile int  iState   = LOW;

void setup()
{
  // open Serial port
  Serial.begin(9600); 
  // set pin13, pin3 as OUTPUTs
  pinMode(iPin13, OUTPUT);
  pinMode(iPin3, INPUT);
  // interrupt1 calls blink() when pin13 flip-flops
  attachInterrupt(1, blink, CHANGE);
  digitalWrite(iPin3, iState);
  Serial.println("\nStart\n");
}//setup()

void loop()
{
  // delay 1 second
  delay(1000);
  // in effect, flip pin13
  Serial.println(iState);
  digitalWrite(iPin13, iState);
  digitalWrite(iPin3, iState);
}//loop()

void blink()
{
  // flip value to trigger interrupt
  iState = !iState;
}//blink()
//END

i finally cracked it!

most annoying though..
..but when i wondered about which pin the interrupt operated on, i went back to the appropriate page.. 

..where i saw that interrupt-0 can be attached to digital pin 2, & interrupt-1 to digital pin 3.

after that, it was pretty much plain sailing - the feedback resistor instead of some weird software, & as can be seen at left, it works beeootifly-thank-yew!

on to my next problem: how can i use LDR hardware to trigger an interrupt (for my "fridge door open" stuff!

{sigh of relief!}.

Projects -- Interrupts

/* example of interrupt function using Arduino 22 */

int                 iPin   = 13;
volatile int  iState = LOW;

void setup()
{
  // open Serial
  Serial.begin(9600); 
  // set pin13 as OUTPUT
  pinMode(iPin, OUTPUT);
  // interrupt1 calls blink() when pin13 flip-flops
  attachInterrupt(1, blink, CHANGE);
  digitalWrite(iPin, 1);
  Serial.println("\nStart\n");
}//setup()

void loop()
{
  // delay 1 second
  delay(1000);
  // in effect, flip pin13
  Serial.println(iState);
  digitalWrite(iPin, iState);
}//loop()

void blink()
{
  // flip value to trigger interrupt
  iState = !iState;
}//blink()
//END

i have been trying to get this interrupt program to work - it doesn't alternate the way i think/assume it should.


it just changes at random, sometimes acting like a touch or proximity switch!

i'm baffled :-?



here's where the example code came from - i've modified it to produce a serial monitor output, & inserted another digitalWrite() statement in the setup to try to get the thing triggering regularly..

..but it doesn't {sigh}..

Project 3 -- Minor Project: schematic

this is the best i could do - i don't know how to make circuit jumper in Fritzing but it should be obvious that that's what they are, not connections..

The 3 'wriggly' things are Peltier elements (Thermistors)

Project 3 -- Minor Project: software

/*
 * Project:    Minor_Project_621
 * Author:     Jane-Maree Howard
 * Date:       Wednesday 21/09/2011
 * Platform:   Arduino 22
 * Purpose:    To demonstate a fridge-control robot
 * Operation:  Several thermistors are mounted inside the fridge.
 *              Their values are read in sequence at 1-minute intervals,
 *              their average is calculated, & the values & their average stored in EEPROM
 *              A LDR is also mounted inside the fridge, to detect when the door is opened.
 *              Change in the LDR resistance trigers an interrupt, & this is also recorded.
               Declare: 
               Setup():             
               Loop():                   
 */
#include                   // EEPROM library

int  iAnalogPin[]    = {0,1,2,3};    // analog pin numbers
int  iLEDpin         = 13;           // door-open LED
int  iDarkLevel      = 100;          // pre-set photocell reading triggering interrupt

int  iGetData        = 0;            // get signal to retrieve data

int  iHeading        = 0;            // signal to print heading
int  iSecond         = 1000;         // 1 second delay &..
int  iMinute         = 60000;        // ..1 minute delay

int  iTemperature[3];                // temperature readings from A0 - A2
int  iAvgTemp;                       // Average of the 3 temperatures

volatile byte iAddressCount   = 0;   // EEPROM address counter
volatile byte bLEDstate       = 0;   // LED pin ON or OFF
 
/* all operations are performed in the setup() section of the program */
void setup()  
{
  delay(iSecond*5);                 // up to 10 minute delay
  pinMode(iLEDpin, OUTPUT);         // LED-pin is an output..
  digitalWrite(iLEDpin,LOW);        // ..initially turned off
  Serial.begin(9600);               // SM @ 9600baud
  // attach interrupt 0, to digital pin 2
  attachInterrupt(0, DoorOpen, CHANGE); // ..on CHANGE
                     
  iGetData  = KeypressInput();      // check for receiving data
  while (iGetData == 0)             // if no signal,start reading..
  {
    // stop interrupts while reading
    noInterrupts();                 // stop interrupts while reading
    iAvgTemp   = 0;                 // zero average Temperature vble               
    /* First read the 3 values into iTemperature[] .. */
    for (byte j=0; j<3; j++)
    { 
      // read value on 3 thermistor pins i.e. iAnalogPin[j]
      iTemperature[j]  = analogRead(iAnalogPin[j]); 
      // now we have to map 0-1023 to 0-255..
      // ..since we want to store the values as bytes..
      iTemperature[j]  = map(iTemperature[j], 0, 1023, 0, 255);
      // ..& write them to EEPROM
      EEPROM.write(iAddressCount, iTemperature[j]);
      // increment the address count..
      iAddressCount++ ;
      iAvgTemp        += iTemperature[j];  // add to average total         
      // delay 10 milliseconds
      delay(10);  
    }//for(j)
    iAvgTemp  = (int)(iAvgTemp/3);
    // write Average to EEPROM also..
    EEPROM.write(iAddressCount, iAvgTemp);
    // ..& increment the address count.
    iAddressCount++ ;
    interrupts();                   // re-enable interrupts
   
    // debugging
    Serial.print("\nrecorded data\t");
    for (int j=0;j<3;j++)
      Serial.print(iTemperature[j]);
    Serial.print(iAvgTemp);
   
    delay(iMinute);                 // delay 1 minute..
    iGetData  = KeypressInput();    // ..then check for receiving data
  }// while(==0) */


 
  while (iGetData != 0)             // ..otherwise, retrieve stored data & send to SM
  {
    if (iHeading%20 == 0)
      Heading();
    iHeading++;
   
    //diagnostic stuff & logic testing
    if (iHeading > 100)
    {
      iGetData  = 0;    // check for receiving data
      iHeading = 0;
    }//if()
   
  }// while(!=0)
}// end setup()

void loop()
{/*nothing done in here*/}//end loop()

/* prints heading to Serial Monitor at pre-set intervals */
void Heading()
{
  Serial.println("\nTemperatures\tT0\tT1\tT2\tT3\tAverage\tDoor\n");
}//Heading()

//END

LIBRARY FUNCTIONS:

/*
 * Project:    LIB04_KeypressInput
 * Author:     Jane-Maree Howard
 * Date:       Saturday 08/10/2011
 * Platform:   Arduino 22
 * Purpose:    To make a library function for inputting a key-press via Serial comm link
 * Operation:  Description: inputs a key-press & returns an Integer
 -             Declare:     NONE - MUST BE DECLARED IN CONJOINING SKETCH(ES)
 -             Setup():     NONE - MUST BE USED ONLY IN CONJOINING SKETCH(ES)
 -                          (used  only in testing)
 -             Procedure(): int KeypressInput();  no parameters   
 -             Loop():      NONE - MUST BE USED ONLY IN CONJOINING SKETCH(ES)
 -                          (used  only in testing)            
 */
int KeypressInput()
{
  /*  inputs a keypress via the Serial comms link
      & returns a non-zero Integer only if there is an input
      CALLED IN MAIN SKETCH  */
  int iKey = 0;
  // send data only when you receive data
  if (Serial.available() > 0)
    iKey = Serial.read();
  return iKey;
}//KeypressInput()
//END


/*
 * Project:    LIB09_photocell_interrupt
 * Author:     Jane-Maree Howard
 * Date:       Thursday 24/11/2011
 * Platform:   Arduino 22
 * Purpose:    To make a Photocell Switch for an interrupt pin (digital 2 or 3).
 * Operation:  The circuit arrangement is the same as the ladyada
 *             LED dimmer, but here the software has a trigger threshold 
 *             for turning the interrupt pin on.
 *             The output of the Analog pin is measured as before,
 *              but instead of analogWrite() to the interrupt pin,
 *              digitalWrite is used to switch the pin on or off.
 *             We don't need to map the Analog pin output,
 *              since it's merely a trigger.
 *             Original description:
 *               "Connect one end of the photocell to 5V, the other end to Analog 0.
 *                Then connect one end of a 4.7K resistor from Analog 0 to ground
 *                Connect LED from pin 9 through a resistor to ground"
 *             Declare, Setup(), Loop(): 
 *              NONE - MUST BE USED ONLY IN CONJOINING SKETCH(ES)
 -             Procedure(): void PhotocellTrigger(int,int,int); 
 -                          void DoorOpen();
 */

/* the photocell pin value is tracked by the interrupt */
void PhotocellTrigger(int iInterruptPin, int iPhotoPin, int iDark)
{
  int iPhotoReading = analogRead(iPhotoPin);     //i.e. analog 0
    //we now use our  'darkLevel' variable to trigger the LED ON.
  if (iPhotoReading > iDark)
    digitalWrite(iInterruptPin, HIGH);          // turn InterruptPin on, else..
  else
    digitalWrite(iInterruptPin, LOW);           // ..turn InterruptPin off 
}//PhotocellTrigger()

/* called when the Interrupt is triggered - records door state */
void DoorOpen()
{
  digitalWrite(iLEDpin, bLEDstate);      // Turn door-open LED ON or OFF..
  EEPROM.write(iAddressCount, bLEDstate);// ..record the incident..
  iAddressCount++;                       // .. increment address count..
  bLEDstate  = !bLEDstate;               // ..& change LED-state ON to OFF or vice versa
}//DoorOpen()
//END

Task 31B -- Making Use of Interrupts

..
Again the schematic is from the Code Project/Interrupts site.

(I had to use a 150Ohm resistor because i couldn't find my push-switch!
  It didn't work quite as well - i should really find that switch! - but i
  suspect my wobbly hand had a lot to do with it; i could try 'de-bouncing'
  the 'switch', but delay() won't work inside the interrupt-triggered function  
  (find the switch, stoopid!)  )


This time, however,  the code makes use of a Hardware Interrupt, as follows:


/*
 * Project:     Interrupts_part_B_621task31
 * Author:     DaveAuld, tidied (not much! :-) ) by Jane-Maree Howard
 * Date:          23 Feb 2010
 * Platform:   Arduino 22
 * Purpose:    To demonstrate a simple interrupt-triggered LED-switch
 * Operation:  Description:
 *             "Set up the Arduino as per the schematic
 *              and upload the code below to the microprocessor.
 *              We will use the same schematic diagram and
 *              modify the code to make use of hardware interrupts.
 *              Now when you upload the code, the LED changes state
 *              whenever the button is pressed
 *              even though the code is still running the same long delay
 *              in the main loop.
 *              [This is code PART B in the downloaded source file.]"
 */
int pbIn = 0;                               // Interrupt 0 is on DIGITAL PIN 2!
int ledOut = 4;                           // The output LED pin
volatile int state = LOW;      // The input state toggle

void setup()
{
  // Set up the digital pin 2 to an Interrupt and Pin 4 to an Output
  pinMode(ledOut, OUTPUT);

  //Attach the interrupt to the input pin and monitor for ANY Change
  attachInterrupt(pbIn, stateChange, CHANGE);
}//setup()

void loop()
{
  //Simulate a long running process or complex task
  for (int i = 0; i < 100; i++)
  {
    // do nothing but waste some time
    delay(50); // Jane-Maree increases delay time from 10ms to 50ms
  }//for()
}//loop()

void stateChange()
{
  state = !state;
  digitalWrite(ledOut, state);
}//stateChange()
//END