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123 lines
3.4 KiB
123 lines
3.4 KiB
//**************************************************************//
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// Name : shiftIn Example 1.1 //
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// Author : Carlyn Maw //
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// Date : 25 Jan, 2007 //
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// Version : 1.0 //
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// Notes : Code for using a CD4021B Shift Register //
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// : //
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//****************************************************************
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//This tut from arduino
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// doesn't work.
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/* IO Definitions ProCAT Flash*/
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//#define DATA_IN 4
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//#define CLK 5
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//#define LATCH_EN 6
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//define where your pins are
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int dataPin = 4;
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int clockPin = 5;
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int latchPin = 6;
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//Define variables to hold the data
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//for shift register.
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//starting with a non-zero numbers can help
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//troubleshoot
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byte switchVar1 = 72; //01001000
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void setup() {
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//start serial
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Serial.begin(9600);
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//define pin modes
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pinMode(latchPin, OUTPUT);
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pinMode(clockPin, OUTPUT);
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pinMode(dataPin, INPUT);
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}
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void loop() {
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//Pulse the latch pin:
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//set it to 1 to collect parallel data
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digitalWrite(latchPin,1);
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//set it to 1 to collect parallel data, wait
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delayMicroseconds(20);
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//set it to 0 to transmit data serially
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digitalWrite(latchPin,0);
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//while the shift register is in serial mode
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//collect each shift register into a byte
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//the register attached to the chip comes in first
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switchVar1 = shiftIn(dataPin, clockPin);
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//Print out the results.
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//leading 0's at the top of the byte
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//(7, 6, 5, etc) will be dropped before
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//the first pin that has a high input
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//reading
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Serial.println(switchVar1, BIN);
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//white space
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Serial.println("-------------------");
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//delay so all these print satements can keep up.
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delay(500);
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}
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//------------------------------------------------end main loop
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////// ----------------------------------------shiftIn function
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///// just needs the location of the data pin and the clock pin
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///// it returns a byte with each bit in the byte corresponding
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///// to a pin on the shift register. leftBit 7 = Pin 7 / Bit 0= Pin 0
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byte shiftIn(int myDataPin, int myClockPin) {
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int i;
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double temp = 0;
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int pinState;
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byte myDataIn = 0;
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pinMode(myClockPin, OUTPUT);
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pinMode(myDataPin, INPUT);
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//we will be holding the clock pin high 8 times (0,..,7) at the
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//end of each time through the for loop
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//at the begining of each loop when we set the clock low, it will
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//be doing the necessary low to high drop to cause the shift
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//register's DataPin to change state based on the value
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//of the next bit in its serial information flow.
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//The register transmits the information about the pins from pin 7 to pin 0
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//so that is why our function counts down
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for (i=7; i>=0; i--)
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{
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digitalWrite(myClockPin, 0);
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delayMicroseconds(0.2);
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temp = digitalRead(myDataPin);
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if (temp) {
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pinState = 1;
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//set the bit to 0 no matter what
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myDataIn = myDataIn | (1 << i);
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}
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else {
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//turn it off -- only necessary for debuging
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//print statement since myDataIn starts as 0
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pinState = 0;
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}
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//Debuging print statements
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//Serial.print(pinState);
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//Serial.print(" ");
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//Serial.println (dataIn, BIN);
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digitalWrite(myClockPin, 1);
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}
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//debuging print statements whitespace
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Serial.println();
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Serial.println(myDataIn, BIN);
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return myDataIn;
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}
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