Coding Outputs: Digital & PWM

# Give your pins easy-to-remember names
i1 = set_name("train_button")
o1 = set_name("red")
o2 = set_name("green")

# ===== Railway crossing lights =====

# This code block executes only once
setup:
    train_button = set_input(push_button, active_low)
    red = set_output(led)
    green = set_output(led)

# This code block executes forever
loop:
    if train_button == ON:  # when train_button is ON
        red = ON  # a train is coming: red ON
    else:  # otherwise
        red = OFF  # turn red OFF
    green = invert(red)  # green is always the opposite of red

Railway crossing lights. While the train button is pressed, red is ON; otherwise it is OFF. green = invert(red) is always the opposite, so exactly one light is on. (Why not just red = train_button? That copies the wire level, and a pressed active-low button reads LOW, so the light would do the opposite!) Reading the output red back needs board firmware 2.26.

# Give your pins easy-to-remember names
i1 = set_name("faster")
i2 = set_name("slower")
o1 = set_name("fan")

# ===== Three-speed fan =====

# This code block executes only once
setup:
    faster = set_input(push_button, active_low)
    slower = set_input(push_button, active_low)
    fan = set_output(fan)
    fan = OFF  # turn fan OFF

# This code block executes forever
loop:
    if faster == ON:  # when faster is ON
        output_increment(fan, 35, 100, 100)  # one step up, never above 100
        wait(300)  # pause here for 300 milliseconds before continuing
    elif slower == ON:  # otherwise, when slower is ON
        output_decrement(fan, 35, 0, 100)  # one step down, never below 0
        wait(300)  # pause here for 300 milliseconds before continuing

A fan with three speeds and two buttons. Each press of faster adds 35 (0 → 35 → 70 → 100, never above 100); slower takes 35 away (never below 0). The wait(300) stops one long press from jumping several speeds.

# Give your pins easy-to-remember names
i1 = set_name("dark")
i2 = set_name("button")
o1 = set_name("lamp")
o2 = set_name("reading_lamp")

# ===== Breathing night light =====

# This code block executes only once
setup:
    dark = set_input(light_sensor, active_low)
    button = set_input(push_button, active_low)
    lamp = set_output(led)
    reading_lamp = set_output(led)

# This code block executes forever
loop:
    if button == ON:  # when button is ON
        output_flip(reading_lamp, 0, 80)  # each press: 80, then 0, then 80 …
        wait(300)  # pause here for 300 milliseconds before continuing
    if dark == ON:  # when dark is ON
        output_increment_till(lamp, 0, 100, 5, 40)  # ramp lamp from 0 up to 100, 5 at a time, 40ms between steps
        output_decrement_till(lamp, 100, 0, 5, 40)  # ramp lamp down from 100 to 0, 5 at a time, 40ms between steps
    else:  # otherwise
        lamp = pwm(0)  # set lamp to 0

A breathing night light. When the light sensor (digital, ON = dark) says it is dark, lamp fades up and down; in daylight it stays off. Each press of button flips the reading_lamp between 80 and 0.