Need Assist in Programing Flowmeter and temperature sensor to the RaspberryPi (Python)

I have experience with the DS1620 temperature sensor.

If this DS18B20 is anywhere close to the DS1620, it's not the easiest temperature sensor to work with. Analog sensors use to be much easier as you just need a lookup table for taking temperature from the analog value read.

Those are digital temperature sensors and have a more or less complex communication protocol to get data out of them. They also use to have signaling - at least the DS1620 - where you program a max and min temperatures Th and Tl and the chip will trigger an alarm when the temperature is higher than Th or lower than Tl. The 1620 also have a Tcom pin that goes high from when one temperature is reached, to when the opposite temperature is reached so it can act as a standalone thermostat is you plug it to a fan or a heater.

I write this so you realize that may be those sensors are more complex than what you need to just make some temperature readings.

With this kind of thermistor TMP36 - Analog Temperature sensor [TMP36] ID: 165 - $1.50 : Adafruit Industries, Unique & fun DIY electronics and kits as example the temp reading is trivial Temp in °C = [(Vout in mV) - 500] / 10.

You just would need some marine heat shrink tube to isolate the sensor and solder it to a wire to have a working sensor like the other one you are linking. And much cheaper I guess.

Anyway if you have already bought the temp sensors, there is a Arduino library you can use with the ardupi or PiFace wiring libraries. That may be the easier path.

Ardupi - Cooking Hacks - Documentation - Raspberry Pi to Arduino shields connection bridge

PiFace wiring - PiFace | Wiring Pi

DS18B20 library - http://www.milesburton.com/?title=Dallas_Temperature_Control_Library

Don't try the same path with the flow meter arduino example though as it uses interrupts, and those are completely different beasts in Arduino and raspberry. In the raspberry you can use separate processes for each reading so you don't need to use interrupts and use a dedicated process for each flow meter instead.

The flow meter you just need to count pulses,  and average the readings to get the flow so it's trivial to dead with it.

It just have a pinwheel with a magnet so each time it spins it sends a pulse when a hall effect sensor detects the magnet passing.

You will also need to calibrate it because I am sure the piping will have something to do with how much liquid is passing by on each spin.

You will also need to have a steady flow, because reflows -liquid going back - will make the pinwheel spin. This is a wild guess from the device description but something to take into account.

What libraries / languages you plan to use ?

... and ...

What kind of output you need ?

It may be easier to separate each sensor in a task and later on plug it all together than to try to get it all working at the same time.

Thanks for the replay.

I actually already have the thermal sensor working with this code

import os

import glob

import time

os.system('sudo modprobe w1-gpio')

os.system('sudo modprobe w1-therm')

base_dir = '/sys/bus/w1/devices/'

sensor1_folder = glob.glob(base_dir + '28-000004a8873d')[0]

sensor1_file = sensor1_folder + 'w1-slave'

def sensor1_raw():

  s1 = open(sensor1_file, 'r')

  s1lines = s1.readlines()

  s1.close()

  return s1lines

def sensor1_temp():

  s1lines = sensor1_ra()

  while s1lines[0].strip()[-3:] !='YES':

  time.sleep(0.2)

  s1lines = sensor1_raw()

  equals_pos = s1lines[1].find('t=')

  if equals_pos != -1:

  tempstarting = s1lines[1][equals_pos+2:]

  temp_c = float(temp_string) / 1000.0

  temp_f = temp_c * 9.0 / 5.0 + 32.0

  return temp_c, temp_f

while True:

  Print(sensor1_temp())

  time.sleep(1)

________________________________________________________________________________

Which prints out the Temperature data every second but my big problem is figuring out how to count the pulses of the flow meter or to count the time between the pulses to get the frequency. That is the part of the program that i need big help with.

Using Python

I have tried this code but i'm doing something wrong it seems.

________________________________________________________________________________

import os # importing OS module just in-case needed

import time # Importing Time module

import RPi.GPIO as gpio # Importing RPIO module as gpio

# Initializing GPIO ports

boardRevision = gpio.RPI_REVISION # Clearing previous gpio port settings

gpio.setmode(gpio.BCM) # Use real physical gpio port numbering

gpio.setup(22, gpio.IN, pull_up_down=gpio.PUD_UP) # setting pin 22 as pull up resistor

while True: # main loop continuously running

  gflowcount = 1 # setting loop execution count

  while gflowcount <= 2: # loop for getting two times to compare

  if (gflowcount == 1 & gpio.input(22) == True): # Executing loop at first loop

  gflowtime1 = int(time.time()*1000) # Getting time of first pulse

  gflowcount = gflowcount + 1

  else if (gflowcount == 2 & gpio.input(22) == True): # Executing loop at second pulse

  gflowtime2 = int(time.time()*1000) # Getting time of second pulse

  else:

  print ('error')

  freq = gflowtime2 - gflowtime1 # Calculating time between two pulses

  hertz = 1000.0000 / freq # Calculating frequency

  flow = hertz / (60 * 7.5) # L/S # Calculating L/S

while True: # loop running every 2 seconds to output the data

  print freq # Printing time between two pulses

  print ('time between two pulse')

  print hertz # printing the frequency

  print ('frequency')

  print flow # Printing L/S

  print ('L/S')

  time.sleep(2) # Pausing for 2 sec.

What is the problem with this second code ?

The indentation is lost when pasting code here, and unfortunately it's hard to follow unindented Python code.

I do apologize, I didn't realize that copy and paste messed with the indentation.

the problem is that only output i see to the screen is the 'error' instead of seeing the frequency. If i can get the frequency i should be able to make it work with that.

Perhaps you want 'and' rather than '&'.  The latter is doing a bitwise AND where I think you want a logical AND?

Regards,

Martyn

I think martyndavies hit the nail on the head.

try with :

  if( (gflowcount == 1) and (gpio.input(22) == True) ):

The same in the next if statement.

else if( (gflowcount == 2) and (gpio.input(22) == True) ):

In other languages - C, Java, ... - the logical AND is written "&&".

May be that's what caused that error.

hey guys i just found out that there's a noise issue with the breadboard that i'm using so i'll need to address that first.

i'll keep in touch. thanks for all your help.

hey guys i'm back. I have fixed the noise issue and have completed most of the program but i need some help to do the final touches.

what i need to do is in the

def glycolFlow():

and in the

def waterFlow():

when those functions are called, inside the function it need to look to see if there is a pulse for 2 seconds. if the pulse is there then the rest of the function can execute if the pulse is not there within 2 seconds then the function returns 0.0 instead of the calculated data.

import os
import glob
import time
import RPi.GPIO as gpio

# Initializing GPIO ports
boardRevision = gpio.RPI_REVISION # Clearing previous gpio port settings
gpio.setmode(gpio.BCM) # Use real physical gpio port numbering
gpio.setup(18, gpio.IN, pull_up_down=gpio.PUD_UP) # setting pin 18 as pull up resistor for glycol flow meter
gpio.setup(25, gpio.IN, pull_up_down=gpio.PUD_UP) # setting pin 12 as pull up resistor for water flow meter


# starting thermal probe drivers
os.system('sudo modprobe w1-gpio')
os.system('sudo modprobe w1-therm')


# setting sensors data file location
sensor1_file = '/sys/bus/w1/devices/28-000004a8873d/w1_slave'
sensor2_file = '/sys/bus/w1/devices/28-00000574c16a/w1_slave'
sensor3_file = '/sys/bus/w1/devices/28-00000561223c/w1_slave'
sensor4_file = '/sys/bus/w1/devices/28-00000560107a/w1_slave'
sensor5_file = '/sys/bus/w1/devices/28-00000560dca6/w1_slave'
sensor6_file = '/sys/bus/w1/devices/28-0000057478b2/w1_slave'


def glycolFlow():
  glycolStartTime = int(time.time())
  print 'glycol start time', glycolStartTime
  glycolCount = 0
  while glycolCount < 15 :
       if gpio.input(18) == True:
            if gpio.input(18) == False:
                 glycolCount += 1
                 print 'glycol count', glycolCount
  glycolEndTime = int(time.time())
  print 'glycol end time', glycolEndTime
  glycolSecsPerLiters = glycolEndTime - glycolStartTime
  glycolLitersPerHour = (3600.0 / glycolSecsPerLiters) * 30
  glycolGalPerHour = glycolLitersPerHour * 0.26417205235815
  return glycolGalPerHour


def waterFlow():
  waterStartTime = int(time.time())
  print 'water start time', waterStartTime
  waterCount = 0
  print 'water count', waterCount
  while waterCount < 15 :
       if gpio.input(25) == True:
            if gpio.input(25) == False:
                 waterCount += 1
                 print 'water count', waterCount
  waterEndTime = int(time.time())
  print 'water end time', waterEndTime
  waterSecsPerLiters = waterEndTime - waterStartTime
  waterLitersPerHour = (3600.0 / waterSecsPerLiters) * 30
  waterGalPerHour = waterLitersPerHour * 0.26417205235815
  return waterGalPerHour


def ts1():
  s1 = open(sensor1_file, 'r')
  s1lines = s1.readlines()
  s1.close()
  while s1lines[0].strip()[-3:] !='YES':
       s1lines = sensor1_raw()
  equals_pos1 = s1lines[1].find('t=')
  if equals_pos1 != -1:
       temp_string1 = s1lines[1][equals_pos1+2:]
       temp_c1 = float(temp_string1) / 1000.0
       temp_f1 = temp_c1 * 9.0 / 5.0 + 32.0
  return temp_c1


def ts2():
  s2 = open(sensor2_file, 'r')
  s2lines = s2.readlines()
  s2.close()
  while s2lines[0].strip()[-3:] !='YES':
       s2lines = sensor2_raw()
  equals_pos2 = s2lines[1].find('t=')
  if equals_pos2 != -1:
       temp_string2 = s2lines[1][equals_pos2+2:]
       temp_c2 = float(temp_string2) / 1000.0
       temp_f2 = temp_c2 * 9.0 / 5.0 + 32.0
  return temp_c2


def ts3():
  s3 = open(sensor3_file, 'r')
  s3lines = s3.readlines()
  s3.close()
  while s3lines[0].strip()[-3:] !='YES':
       s3lines = sensor3_raw()
  equals_pos3 = s3lines[1].find('t=')
  if equals_pos3 != -1:
       temp_string3 = s3lines[1][equals_pos3+2:]
       temp_c3 = float(temp_string3) / 1000.0
       temp_f3 = temp_c3 * 9.0 / 5.0 + 32.0
  return temp_c3


def ts4():
  s4 = open(sensor4_file, 'r')
  s4lines = s4.readlines()
  s4.close()
  while s4lines[0].strip()[-3:] !='YES':
       s4lines = sensor4_raw()
  equals_pos4 = s4lines[1].find('t=')
  if equals_pos4 != -1:
       temp_string4 = s4lines[1][equals_pos4+2:]
       temp_c4 = float(temp_string4) / 1000.0
       temp_f4 = temp_c4 * 9.0 / 5.0 + 32.0
  return temp_c4


def ts5():
  s5 = open(sensor5_file, 'r')
  s5lines = s5.readlines()
  s5.close()
  while s5lines[0].strip()[-3:] !='YES':
       s5lines = sensor5_raw()
  equals_pos5 = s5lines[1].find('t=')
  if equals_pos5 != -1:
       temp_string5 = s5lines[1][equals_pos5+2:]
       temp_c5 = float(temp_string5) / 1000.0
       temp_f5 = temp_c5 * 9.0 / 5.0 + 32.0
  return temp_c5


def ts6():
  s6 = open(sensor6_file, 'r')
  s6lines = s6.readlines()
  s6.close()
  while s6lines[0].strip()[-3:] !='YES':
       s6lines = sensor6_raw()
  equals_pos6 = s6lines[1].find('t=')
  if equals_pos6 != -1:
       temp_string6 = s6lines[1][equals_pos6+2:]
       temp_c6 = float(temp_string6) / 1000.0
       temp_f6 = temp_c6 * 9.0 / 5.0 + 32.0
  return temp_c6


while True:
  glycolGalPerHour = glycolFlow()
 if glycolGalPerHour != 0.0:
       ts1 = ts1()
       ts2 = ts2()
       ts3 = ts3()
       ts4 = ts4()
 else:
       ts1 = 0
       ts2 = 0
       ts3 = 0
       ts4 = 0
  waterGalPerHour = waterFlow()
 if waterGalPerHour != 0.0:
       ts6 = ts6()
       ts5 = ts5()
 else:
       ts5 = 0
       ts6 = 0
  ts5 = ts5()
  ts6 = ts6()
  print "Glycol flow =", glycolGalPerHour, "Gal/Hour"
  print('sensor1', ts1)
  print('sensor2', ts2)
  print('sensor3', ts3)
  print('sensor3', ts4)
  print "water flow =", waterGalPerHour, "Gal/Hour"
  print('sensor5', ts5)
  print('sensor6', ts6)
  print '---------------------------------'
  time.sleep(30)

Hi Priyam,

Can I get your advice on programming a hall-effect flow meter with the Raspberry Pi?

Ultimately I would like to log the water flow data over time and then calculate the total volume of each continuous stream (ie. if flow drops to 0 for x seconds then start a new total).

As a start, I want to make sure that I can replicate your implementation. Will this (below) do the job?

    import os  
    import glob  
    import time  
    import RPi.GPIO as gpio  
      
    # Initializing GPIO ports  
    boardRevision = gpio.RPI_REVISION # Clearing previous gpio port settings  
    gpio.setmode(gpio.BCM) # Use real physical gpio port numbering  
     gpio.setup(25, gpio.IN, pull_up_down=gpio.PUD_UP) # setting pin 12 as pull up resistor for water flow meter  
      
      
    def waterFlow():  
      waterStartTime = int(time.time())  
      print 'water start time', waterStartTime  
      waterCount = 0  
      print 'water count', waterCount  
      while waterCount < 15 :  
           if gpio.input(25) == True:  
                if gpio.input(25) == False:  
                     waterCount += 1  
                     print 'water count', waterCount  
      waterEndTime = int(time.time())  
      print 'water end time', waterEndTime  
      waterSecsPerLiters = waterEndTime - waterStartTime  
      waterLitersPerHour = (3600.0 / waterSecsPerLiters) * 30   
      return waterLitersPerHour  
      
      print "water flow =", waterLitersPerHour, "l/Hour"  

      print '---------------------------------'  
      time.sleep(30) 

no that was just another test program not working properly.

the program below is the that i'm using at the moment.

it first checks to see if there is a flow or not. if there is no flow then it returns zero. if there flow then it returns the instantaneous flow rate by looking at the pulses that the flow meter is putting out but if the flow stops before there is enough data to be able to calculate the flow then it will return zero. from there you can take those data points and plot them on excel and figure out the area under the curve to get your total flow from starting to stop and for how long it stopped also.

import os # importing OS module just in-case needed 
import time # Importing Time module
import RPi.GPIO as gpio # Importing RPIO module as gpio


# Initializing GPIO ports
boardRevision = gpio.RPI_REVISION # Clearing previous gpio port settings
gpio.setmode(gpio.BCM) # Use real physical gpio port numbering
gpio.setup(25, gpio.IN, pull_up_down=gpio.PUD_UP) # setting pin 22 as pull up resistor


def glycolFlow():
  glycolCurrentTime = int(time.time())
  glycolErrorStopTime = glycolCurrentTime + 1
  glycolTimingPulse = 0
  while glycolCurrentTime <= glycolErrorStopTime:
       if gpio.input(25) == True:
            if gpio.input(25) == False:
                 glycolTimingPulse += 1
            else:
                 glycolCurrentTime = int(time.time())
       else:
            glycolCurrentTime = int(time.time())

  if glycolTimingPulse != 0:
       glycolStartTime = int(time.time())
       print 'glycol start time', glycolStartTime
       waitTimerglycol = glycolStartTime + 2
       waitTimerCountglycol = int(time.time())
       glycolCount = 0
       print 'glycol count', glycolCount
       while (glycolCount < 15) and (waitTimerCountglycol <= waitTimerglycol) :
            if gpio.input(25) == True:
                 if gpio.input(25) == False:
                      glycolCount += 1
                      print 'glycol count', glycolCount
                      waitTimerglycol = int(time.time()) + 1
                 else:
                      waitTimerCountglycol = int(time.time())
            else:
                 waitTimerCountglycol = int(time.time())
      glycolEndTime = int(time.time())
       print 'glycol end time', glycolEndTime
       if glycolCount == 15:
            glycolSecsPerLiters = glycolEndTime - glycolStartTime
            glycolLitersPerHour = (3600.0 / glycolSecsPerLiters) * 30
            glycolGalPerHour = glycolLitersPerHour * 0.26417205235815
            return glycolGalPerHour
       else:
            glycolGalPerHour = 0
       return glycolGalPerHour
  else:
       glycolGalPerHour = 0
       return glycolGalPerHour

while True:
  glycolGalPerHour = glycolFlow()
  print "glycol flow =", glycolGalPerHour, "Gal/Hour"