ATtiny85 - Bi-direction Traffic Stop Light

/* ATtiny85 - Advanced Traffic Stop Light - Version 0.1.0 - 2020-02-18
 * Copyright (c) 2020 Matt Rude <matt@mattrude.com>
 * 
 * *********************************************************************************
 * 
 * This is a Advanced Traffic Stop Light program written for an ATtiny85 using
 * Arduino IDE.
 * 
 * The program was written for an ATtiny85 using Arduino IDE and the 'ATTinyCore'
 * board found at: https://github.com/SpenceKonde/ATTinyCore
 * 
 * For more on the ATtiny85, see: https://www.microchip.com/wwwproducts/en/ATtiny85
 * 
 * The ATtiny85 was programed with the external programer, and is running is at a
 * clock speed of 1MHz (internal).
 * 
 * The circuit is powered by an external DC buck converter running at 5v.
 * 
 * *********************************************************************************
 * 
 * Required Hardware:
 *  
 * - 1x 1330 ATtiny85-20pu
 * - 1x 74HC959 Shift Register
 * - 2x Red LED
 * - 2x Yellow LED
 * - 2x Green LED
 * - 6x 220 ohm Resistors
 * - 1x Large Breadboard
 * - 20x Jumper Wires
 * 
 * Simplified ATtiny85 Pinout:
 *   (Note: the dot next to the Reset pin represents the dot on the chip.)             
 *              ______     
 *     Reset - |.     | - +5v
 *    A3 - 3 - |      | - 2 - A1
 *    A2 - 4 - |      | - 1 - PWM
 *       GND - |______| - 0 - PWM
 *
 * 74HC959 Shift Register Pinout:
 *   (Note: the dot next to the Q1 pin represents the dot on the chip.)             
 *              ______
 *        Q1 - |.     | - +5v
 *        Q2 - |      | - Q0
 *        Q3 - |      | - DS
 *        Q4 - |      | - OE
 *        Q5 - |      | - STCP
 *        Q6 - |      | - SHCP
 *        Q7 - |      | - MR
 *       GND - |______| - Q7S
 * 
 * *********************************************************************************
 * 
 * Changelog:
 * 
 * 2020-02-18 - 0.1.0 - Initial Release.
 * 
 * *********************************************************************************
 * 
 * MIT License
 * 
 * Copyright (c) 2020 Matt Rude <matt@mattrude.com>
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 * 
 * *********************************************************************************
 */

// This is the amount of time, in seconds, to wait between light changes.
int changeDelay = 30;

// Declare the shift register pins
int clockPin    = 0;      // Connected to SHCP (pin 11) on the 74HC595.
int latchPin    = 1;      // Connected to STCP (pin 12) on the 74HC595.
int dataPin     = 2;      // Connected to DS (pin 14) on the 74HC595.

void setup() {
  // Set the three shift register pins to output.
  pinMode(clockPin, OUTPUT);
  pinMode(latchPin, OUTPUT);
  pinMode(dataPin, OUTPUT);

  // Start with the clockPin set to a LOW state
  digitalWrite(clockPin, LOW);
}

void loop() {
  // Set the Both directions to Red
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0b00100010);
  digitalWrite(latchPin, HIGH);
  delay((changeDelay*100)/8);

  // Set the first directions to Green and the second to Red
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0b10000010);
  digitalWrite(latchPin, HIGH);
  delay(changeDelay*100);

  // Set the first directions to Yellow and keep the second direction Red
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0b01000010);
  digitalWrite(latchPin, HIGH);
  delay((changeDelay*100)/4);

  // Set the Both directions to Red
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0b00100010);
  digitalWrite(latchPin, HIGH);
  delay((changeDelay*100)/8);

  // Set the first directions to Red and the second to Green
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0b00101000);
  digitalWrite(latchPin, HIGH);
  delay(changeDelay*100);

  // Set the first directions to Yellow and keep the second direction Red
  digitalWrite(latchPin, LOW);
  shiftOut(dataPin, clockPin, MSBFIRST, 0b00100100);
  digitalWrite(latchPin, HIGH);
  delay((changeDelay*100)/4);
}