89 lines
2.6 KiB
C++
89 lines
2.6 KiB
C++
//**************************************************************//
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// Name : shiftOutCode, Dual Binary Counters //
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// Author : Carlyn Maw, Tom Igoe //
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// Date : 25 Oct, 2006 //
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// Version : 1.0 //
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// Notes : Code for using a 74HC595 Shift Register //
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// : to count from 0 to 255 //
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//**************************************************************//
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//Pin connected to ST_CP of 74HC595
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int latchPin = 8;
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//Pin connected to SH_CP of 74HC595
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int clockPin = 12;
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////Pin connected to DS of 74HC595
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int dataPin = 11;
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void setup() {
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//Start Serial for debuging purposes
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Serial.begin(9600);
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//set pins to output because they are addressed in the main loop
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pinMode(latchPin, OUTPUT);
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}
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void loop() {
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//count up routine
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for (int j = 0; j < 256; j++) {
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//ground latchPin and hold low for as long as you are transmitting
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digitalWrite(latchPin, 0);
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//count up on GREEN LEDs
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shiftOut(dataPin, clockPin, j);
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//count down on RED LEDs
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shiftOut(dataPin, clockPin, 255-j);
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//return the latch pin high to signal chip that it
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//no longer needs to listen for information
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digitalWrite(latchPin, 1);
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delay(1000);
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}
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}
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void shiftOut(int myDataPin, int myClockPin, byte myDataOut) {
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// This shifts 8 bits out MSB first,
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//on the rising edge of the clock,
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//clock idles low
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..//internal function setup
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int i=0;
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int pinState;
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pinMode(myClockPin, OUTPUT);
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pinMode(myDataPin, OUTPUT);
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. //clear everything out just in case to
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. //prepare shift register for bit shifting
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digitalWrite(myDataPin, 0);
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digitalWrite(myClockPin, 0);
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//for each bit in the byte myDataOut<75>
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//NOTICE THAT WE ARE COUNTING DOWN in our for loop
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//This means that %00000001 or "1" will go through such
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//that it will be pin Q0 that lights.
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for (i=7; i>=0; i--) {
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digitalWrite(myClockPin, 0);
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//if the value passed to myDataOut and a bitmask result
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// true then... so if we are at i=6 and our value is
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// %11010100 it would the code compares it to %01000000
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// and proceeds to set pinState to 1.
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if ( myDataOut & (1<<i) ) {
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pinState= 1;
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}
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else {
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pinState= 0;
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}
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//Sets the pin to HIGH or LOW depending on pinState
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digitalWrite(myDataPin, pinState);
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//register shifts bits on upstroke of clock pin
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digitalWrite(myClockPin, 1);
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//zero the data pin after shift to prevent bleed through
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digitalWrite(myDataPin, 0);
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}
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//stop shifting
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digitalWrite(myClockPin, 0);
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}
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