Raspberry Pi Pomodoro timer with lights (using JamHat hobby board )

This is a timer for the Raspberry Pi that lights the lights on the JamHat Hobby Board as the timer progresses through its cycle. I use it as a Pomodoro Timer for timing 30 minute intervals.

When you click the blue button, that starts the timer (its set to 30 minutes by default, but this can be altered by changing the timer variable ).

The lights come on at equal times in the cycle so after 15 minutes there are 3 of the 6 lights lit. When 30 minutes is completed a tune plays (well a couple of beeps, sounds very 8-bit ).

Its functionality is all in the code python below. I’ve started the script in an infinite loop (via crontab), so it functions standalone on start up (no need to trigger anything, other than starting it via the blue button on the Jamhat board).

@reboot python /home/pi/mytimer.py &

The & in the script above runs the program in the background so other functionality is not affected on startup (ie it doesn’t halt anything as its spawns a child process).

# gpiozero contains the JamHat object (the little circuit board with the lights and buzzer on it)
from gpiozero import JamHat
from time import sleep
import math


######################################################### functions #########################################################
def play_end_timer_tune(jamhat): 
    jamhat.buzzer.play('C4')
    sleep(0.5)
    jamhat.off()

    jamhat.buzzer.play(70)
    sleep(0.5)
    jamhat.off()

    jamhat.buzzer.play(220.0)
    sleep(0.5)

######################################################### do the calculation to work out how many lights to turn on #########################################################
def calc_number_lights_to_switch_on(jamhat, loopcounter, selectedTimer ):
    # reset all lights
    jamhat.off()        
    totalNumLeds = 6
    gapForEachLight = float(selectedTimer) / float(totalNumLeds)

    numberOfLightsToLightNow = float(loopcounter) / float(gapForEachLight)    
    numberOfLightsToLightNow = math.ceil(numberOfLightsToLightNow)
    turnOnThisManyLights(jamhat, numberOfLightsToLightNow)

def turnOnThisManyLights(jamhat, numberOfLedsToLight):    
   
    print("numberOfLedsToLight = "+str(numberOfLedsToLight))
    lights = ["jamhat.lights_1.red.on()", "jamhat.lights_1.yellow.on()", "jamhat.lights_1.green.on()",
        "jamhat.lights_2.red.on()", "jamhat.lights_2.yellow.on()", "jamhat.lights_2.green.on()"]
    # loop array based on numberOfLedsToLight
    i = 0
    while i < numberOfLedsToLight:
        eval(lights[i])        # call eval on each element in the array , up to the count e.g. eval('aVar = aVar + 1')
        i += 1
    sleep(6)        # keeps the loop count timer the same (so all calculations should work on timting )

def turn_off_all_lights_and_turn_on_green_lights_to_indicate_ready(jamhat):    
   
    # reset it
    jamhat.off()
    # Turn the green lights on (indciates booted and program ready)
    jamhat.lights_1.green.on()
    jamhat.lights_2.green.on()    

######################################################### end of functions #########################################################
    
######################################################### start of main program #########################################################
# Initialise the JamHat object.
jamhat = JamHat()

turn_off_all_lights_and_turn_on_green_lights_to_indicate_ready(jamhat)

# 30 minutes timer  60 seconds * 30mins = 1800 seconds / 6 (each loop takes 6 seconds ) = 300
timerLength = 300  # 300 = 30 mins
# e.g. if you wanted a 5minute timer = 60 * 5 = 300 / 6 = 50
# timer = 50   # 5 minute timer

print ("funky timer bootingy !")

# Setup infinite loop in try / catch so user can CTRL+C terminate (if and only if keyboard attached)
try:
    while True:
        if(jamhat.button_1.is_pressed): # blue button            
            # each looper needs to go until 300 ( which is equal to 30 minutes )                                               
            loopcounter = 0

            selectedTimer = timerLength					

            while loopcounter < selectedTimer:
                calc_number_lights_to_switch_on(jamhat, loopcounter, selectedTimer)                
                loopcounter += 1    

            # loop ends after 30 minutes PLAY BUZZER
            play_end_timer_tune(jamhat)

        turn_off_all_lights_and_turn_on_green_lights_to_indicate_ready(jamhat)           
           
        sleep(0.1)

except KeyboardInterrupt:
    # If someone presses CTRL+C, close the JamHat, freeing of the Pins for use elsewhere.
    jamhat.close()