Electronics is fun...

Discussion in 'The Projects Forum' started by aka-rato, May 22, 2012.

  1. aka-rato

    Thread Starter Member

    May 11, 2012
    58
    0
    hello

    i was building a circuit using a shift register 74HC595, 8 leds and 8 resistors, the i connected that to my open source electronics prototyping platform. i was expecting to see the shifting but instead it could only shift when i bring my hand very close to the circuit, then i realised there must be a sensor somewhere on the prototyping cicuit. i came across a SPK16.000G i think this is a sensor so can you guys explain to me how does it work n can i find it if i want to buy it.:confused:


    thank you.
     
  2. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    Schematics, links, more information?
     
  3. aka-rato

    Thread Starter Member

    May 11, 2012
    58
    0
    this is the program.


    //Pin Definitions
    //Pin Definitions
    //The 74HC595 uses a serial communication
    //link which has three pins
    int data = 2;
    int clock = 3;
    int latch = 4;

    //Used for single LED manipulation
    int ledState = 0;
    const int ON = HIGH;
    const int OFF = LOW;


    /*
    * setup() - this function runs once when you turn your Arduino on
    * We set the three control pins to outputs
    */
    void setup()
    {
    pinMode(data, OUTPUT);
    pinMode(clock, OUTPUT);
    pinMode(latch, OUTPUT);
    }

    /*
    * loop() - this function will start after setup finishes and then repeat
    * we set which LEDs we want on then call a routine which sends the states to the 74HC595
    */
    void loop() // run over and over again
    {
    int delayTime = 100; //the number of milliseconds to delay between LED updates
    for(int i = 0; i < 256; i++){
    updateLEDs(i);
    delay(delayTime);
    }
    }



    /*
    * updateLEDs() - sends the LED states set in ledStates to the 74HC595
    * sequence
    */
    void updateLEDs(int value){
    digitalWrite(latch, LOW); //Pulls the chips latch low
    shiftOut(data, clock, MSBFIRST, value); //Shifts out the 8 bits to the shift register
    digitalWrite(latch, HIGH); //Pulls the latch high displaying the data
    }

    /*
    * updateLEDsLong() - sends the LED states set in ledStates to the 74HC595
    * sequence. Same as updateLEDs except the shifting out is done in software
    * so you can see what is happening.
    */
    void updateLEDsLong(int value){
    digitalWrite(latch, LOW); //Pulls the chips latch low
    for(int i = 0; i < 8; i++){ //Will repeat 8 times (once for each bit)
    int bit = value & B10000000; //We use a "bitmask" to select only the eighth
    //bit in our number (the one we are addressing this time through
    value = value << 1; //we move our number up one bit value so next time bit 7 will be
    //bit 8 and we will do our math on it
    if(bit == 128){digitalWrite(data, HIGH);} //if bit 8 is set then set our data pin high
    else{digitalWrite(data, LOW);} //if bit 8 is unset then set the data pin low
    digitalWrite(clock, HIGH); //the next three lines pulse the clock pin
    delay(1);
    digitalWrite(clock, LOW);
    }
    digitalWrite(latch, HIGH); //pulls the latch high shifting our data into being displayed
    }


    //These are used in the bitwise math that we use to change individual LEDs
    //For more details http://en.wikipedia.org/wiki/Bitwise_operation
    int bits[] = {B00000001, B00000010, B00000100, B00001000, B00010000, B00100000, B01000000, B10000000};
    int masks[] = {B11111110, B11111101, B11111011, B11110111, B11101111, B11011111, B10111111, B01111111};
    /*
    * changeLED(int led, int state) - changes an individual LED
    * LEDs are 0 to 7 and state is either 0 - OFF or 1 - ON
    */
    void changeLED(int led, int state){
    ledState = ledState & masks[led]; //clears ledState of the bit we are addressing
    if(state == ON){ledState = ledState | bits[led];} //if the bit is on we will add it to ledState
    updateLEDs(ledState); //send the new LED state to the shift register
    }
     
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