flowmeter.py

# From https://github.com/adafruit/Kegomatic
import time
import random

class FlowMeter():
    PINTS_IN_A_LITER = 2.11338
    SECONDS_IN_A_MINUTE = 60
    MS_IN_A_SECOND = 1000.0
    displayFormat = 'metric'
    beverage = 'beer'
    enabled = True
    clicks = 0
    lastClick = 0
    clickDelta = 0
    hertz = 0.0
    flow = 0 # in Liters per second
    thisPour = 0.0 # in Liters
    totalPour = 0.0 # in Liters

    def __init__(self, displayFormat, beverage):
        self.displayFormat = displayFormat
        self.beverage = beverage
        self.clicks = 0
        self.lastClick = int(time.time() * FlowMeter.MS_IN_A_SECOND)
        self.clickDelta = 0
        self.hertz = 0.0
        self.flow = 0.0
        self.thisPour = 0.0
        self.totalPour = 0.0
        self.enabled = True

    def update(self, currentTime):
        self.clicks += 1
        # get the time delta
        self.clickDelta = max((currentTime - self.lastClick), 1)
        # calculate the instantaneous speed
        if (self.enabled == True and self.clickDelta < 1000):
            self.hertz = FlowMeter.MS_IN_A_SECOND / self.clickDelta
            self.flow = self.hertz / (FlowMeter.SECONDS_IN_A_MINUTE * 7.5)  # In Liters per second
            instPour = self.flow * (self.clickDelta / FlowMeter.MS_IN_A_SECOND)
            self.thisPour += instPour
            self.totalPour += instPour
        # Update the last click
        self.lastClick = currentTime

    def getBeverage(self):
        return str(random.choice(self.beverage))

    def getFormattedClickDelta(self):
        return str(self.clickDelta) + ' ms'

    def getFormattedHertz(self):
        return str(round(self.hertz,3)) + ' Hz'

    def getFormattedFlow(self):
        if(self.displayFormat == 'metric'):
            return str(round(self.flow,3)) + ' L/s'
        else:
            return str(round(self.flow * FlowMeter.PINTS_IN_A_LITER, 3)) + ' pints/s'

    def getThisPour(self):
        return round(self.thisPour, 3)

    def clearThisPour(self):
        self.thisPour = 0

    def getFormattedThisPour(self):
        if(self.displayFormat == 'metric'):
            return str(round(self.thisPour,3)) + ' L'
        else:
            return str(round(self.thisPour * FlowMeter.PINTS_IN_A_LITER, 3)) + ' pints'

    def getFormattedTotalPour(self):
        if(self.displayFormat == 'metric'):
            return str(round(self.totalPour,3)) + ' L'
        else:
            return str(round(self.totalPour * FlowMeter.PINTS_IN_A_LITER, 3)) + ' pints'

    def clear(self):
        self.thisPour = 0;
        self.totalPour = 0;