ATtiny85 Traffic Stop Light - Written with the Atmel Studio 7 - This program turns on (in order) the Red LED, waits for 5 seconds, then turns on the Green LED, waits for 5 seconds, then turns on the Yellow LED, waits for 2.5 seconds and repeats cycle.

ATtiny85_TrafficStopLight.c

/* ATtiny85 Traffic Stop Light - Version 0.2.0 - 2020-03-07
 * Copyright (c) 2020 Matt Rude <matt@mattrude.com>
 * 
 * *********************************************************************************
 * 
 * This is a simple Traffic Stop Light program written for an ATtiny85 using
 * Atmel Studio 7: https://www.microchip.com/mplab/avr-support/atmel-studio-7
 * 
 * For more on the ATtiny85, see: https://www.microchip.com/wwwproducts/en/ATtiny85
 * 
 * The program turns on (in order) the Red LED, waits for 5 seconds, then turns on
 * the Green LED, waits for 5 seconds, then turns on the Yellow LED, waits for 2.5
 * seconds and repeats cycle.
 * 
 * The ATtiny85 was programed with the external programmer, and is running is at a
 * clock speed of 1MHz (internal).
 * 
 * The circuit is powered by an external DC buck converter running at 3.3v.
 * 
 * *********************************************************************************
 * 
 * Required Hardware:
 * 
 * - 1x 1330 ATtiny85-20pu
 * - 1x Red LED
 * - 1x Yellow LED
 * - 1x Green LED
 * - 1x 220ohm Resistor
 * - 1x Breadboard
 * - 8x Jumper Wires
 * 
 * Simplified ATtiny85 pin out:
 * (Note: the dot next to the Reset pin, represents the dot on the chip.)
 *                ______
 * Reset - PB5 - |.     | - VCC - 5v+
 *    A3 - PB3 - |      | - PB2 - A1
 *    A2 - PB4 - |      | - PB1 - PWM
 *         GND - |______| - PB0 - PWM
 *
 * 
 * *********************************************************************************
 * 
 * Changelog:
 * 
 * 2020-03-07 - 0.2.0 - Convert to use Atmel Studio 7 opposed to Arduino IDE
 * 2020-02-15 - 0.1.2 - Change program to boot with the Red light first.
 *                    - Change Red & Green delay to 5 seconds, and Yellow to 2.5.
 * 2020-02-02 - 0.1.1 - Correct minor spelling and white space cleanup.
 * 2020-01-30 - 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.
 * 
 * *********************************************************************************
 */

#define F_CPU 1000000UL         // Set the CPU clock frequency to 1MHz

// Add the required libraries to the project
#include <util/delay.h>         // The delay.h library is used to pause the program
#include <avr/io.h>             // The io.h library is used to communicate with pins

// Define the pins used and how they are used
#define redLed PB0              // Set pin 0 as the Red pin
#define yellowLed PB1           // Set pin 1 as the Yellow pin
#define greenLed PB2            // Set pin 2 as the Green pin

// Starting the main loop
int main(void) {
    // Initialize the digital pins as Outputs.
    DDRB |= (1<<PB0);           // Setting Red LED as output
    DDRB |= (1<<PB1);           // Setting Yellow LED as output
    DDRB |= (1<<PB2);           // Setting Green LED as output

    // Start the primary loop
    while (1) {
        PORTB |= (1<<redLed);           // Turn the Red LED on.
        _delay_ms(5000);                // Wait for 5 seconds.
        PORTB &= ~(1<<redLed);          // Turn the Red LED off.
        PORTB |= (1<<greenLed);         // Turn the Green LED on.
        _delay_ms(5000);                // Wait for 5 seconds.
        PORTB &= ~(1<<greenLed);        // Turn the Green LED off.
        PORTB |= (1<<yellowLed);        // Turn the Yellow LED on.
        _delay_ms(2500);                // Wait for 2.5 seconds.
        PORTB &= ~(1<<yellowLed);       // Turn the Yellow LED off.
    } // Ending the primary loop
}  // Ending main main loop