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- เผยแพร่เมื่อ 16 ก.ค. 2017
- An RPi experiment using the YF-S201 flow meter. Good demo of measuring and controlling water flows - home watering use, irrigation water use tracking, livestock water tanks, etc.
Line 37: print('Time (min & clock) ', minutes, '\t', time.asctime(time.localtime(time.time())),'
')
NOTE: The pi is not a real time computer (for example like the Arduino) and its ability to react to polling or interrupts is dependent on other code being executed. As a result, at higher input rates, the pi will begin to miss inputs and the results will be less and less accurate. You can put in factors based on assumptions (as in this example) to get reasonable approximations.
The sensor is inline and uses an impeller with an embedded magnet. The magnet triggers a Hall effect switch sending a pulse at each revolution.
There are 3 wires, red (power, 2-24 volts, but I've gotten it to work at 3 volts), black (ground) and yellow (Hall effect output).
From the spec sheet:
16 Hz = 2 L/min = 120 L/hr
32.5 Hz = 4 L/min = 240 L/hr
49.3 Hz = 6 L/min = 360 L/hr
65.5 Hz = 8 L/min = 480 L/hr
82 Hz = 10 L/min = 600 L/hr
etc. Max 30 L/min
Frequency (Hz) = 7.5 * Flow rate (L/min)
Pulses per Liter: 450
Model: YF-S201
Sensor Type: Hall effect
Working Voltage: 3.5 to 24V DC (min tested voltage 3.3V)
Max current draw: 15mA @ 5volts
Output Type: 5volt TTL
Working Flow Rate: 1 to 30 Liters/Minute
Accuracy: ±10%
Maximum water pressure: 2.0 MPa
Operating Temperature: ≤80℃
Liquid Temperature: ≤120℃
Output duty cycle: 50% ±10%
Output rise time: 0.04us
Output fall time: 0.18us
Min Durability: 300,000 cycles
Cable length: 15cm
1/2" nominal pipe connections, 0.78" outer diameter, 1/2" of thread
Size: 2.5" x 1.4" x 1.4"
Notes: I found that when the impeller stops with the Hall effect switch triggered, it keeps sending pules to the RPi. Seems to be a Pi triggering issue per the internet.
YOU NEED A VOLTAGE DIVIDER WHEN OPERATING ABOVE 3.3 VOLTS!!!
MATERIALS
- Raspberry Pi (and Pi power supply)
- Breadboard
- YF-S201 Water meter / sensor
- Jumpers
WARNING: Warning: mis-wiring or mis-programming your Pi or miswiring of accessories can ruin the Pi and accessories. Data is from the manufacturer. Information/drawings offered as is. Use at your own risk. If you don't know, learn first.
so happy to see my flow sensor video.
That's sweet. I need it to measure flow through a project. Someone interested in the project needs the flow rate quantified. I think I would rewrite the code to print a graph of the flow rate every 1 second to see if it varies. thanks
Thanks a lot for this valuable video.
You are most welcome
A common practice used tracking an input that can remain in a unknown state, i.e either 0 or 1, is to detect the rising edge of the input. In you code a count would be triggered only when the input transitioned from no flow (0) to flow (1). Using this technique it does not matter what the input state is only that it did make a transition indicating that flow is occuring.
You are right of course and the pi is supposed to be able to do that with interrupts, but it did not work. I found a bug report on it, so I think it's not just me.
I'm not sure if this has been mentioned before, but I figured out how to solve the getting 1's as inputs even when the impeller is stationary. If the impeller has been turning in the opposite direction as it does when air flows through in the correct direction, it shows 1. If you blow through in the correct direction before running the programme it corrects itself and goes back to 0. Not sure if this will help anyone but just thought I'd mention what I found.
same here
he already solve the impeller problem, thanks you mention
th-cam.com/video/0fqoq1jWlts/w-d-xo.html
very informative
Im having issues with line 37, what is the complete code? I have used the following;
print('Time (min & clock) ', minutes, '\t', time.asctime(time))
Sorry, got cut off. This is copy and pasted from the program:
print('Time (min & clock) ', minutes, '\t', time.asctime(time.localtime(time.time())),'
')
It's also now in the description.
Can you do the programming with a 2-wire pulse-output flow meter (w/reed switch) instead? These flow meters are going down in price to make them competitive with hall-effect flow sensors. Plus, they don't need an external voltage supply to produce the pulse signal.
It should be almost the same program. You don't need the power. Just detect the switch closed / open. I will look into it, but this is just a hobby and so I don't know when I can get around to doing it.
Do you think this water sensor can be used for like laser engraving machine like a water protection switch to detect if there is no water flowing and say to machine to stop work if the pump get break for example
I think you can calculate the constant by spec (450 pulse per liter). Just divide the number of pulses between 450 and multiply by the time unit you are measuring (e.g. 60 secs to get Lt/min). However I used the wiring and was OK!! Thanks!
That sounds correct. But you must consider the speed of the computer as well, if you are just running a small program that will work, but as the program grows in complexity, the polling / interrupts don't always happen as timed.
Nice project. I am curious, I have this running and I am getting pulses but far fewer than expected. Could that be due to the resistor sizes I determined as part of my voltage divider? I am only getting ~5 pulses every minutes when I know the impeller is spinning much faster than that. Any ideas? I am getting a reading, it's just way under what it should be.
There is a max rpm that it is rated for, and it is pretty low. I have info in the description. Also, any amount of code causes the pi to start missing pulses. I have a couple videos on this meter exploring ways to improve accuracy.
Great demo, thanks for sharing. Just out of curiosity, how are you planning to use the flow meter? Apologies if I missed that in the video.
Thank you. No plans, I bought it because it was on sale. ;) Now I have to find something to use it for.
Hi, I have everything needed (electronics and hardware) and I tried to copy the program as you have it written but I'm getting a syntax error at "if GPIO.input(input)!= 0 #Look for pulses". It highlights everything after that red and won't let me begin the program. Is there any way I could download your copy of this program so I can be sure there are no mistakes?
Just saw your comment. You probably have an error on the line above it. Look for missing ) or : or such.
Since I wrote this comment I have been able to make some progress. I took your code and modified it to suit my needs. I am in need of some extra help though. I have even gone to my local tech school to find someone who knows python and GPIO but am having a really hard time finding the help I need.
What I am trying to do is use a flow meter and solenoid to automatically dispense 5 gallons of fluid from a pressurized source (PVC pipe) upon a button press. I also need a button to interrupt flow as an emergency stop (shut the solenoid to resting position.
I have the elctronics hooked up and pieced together including sensor, solenoid, resistors, transistors, 12v relay etc. The code is currently scattered among different programs. One program is able to open the solenoid upon start (run) program and stay open until the total count reaches a certain number and then shut. Another program will open the solenoid at a button press and stay open but it's not reading impulses the way i would like it to (technically its not reading the input at all). I am having a hard time bringing these features together into one program.
I would really like to get this project done and am looking for some help from someone who is much more experienced in python coding than myself. Is there any way we can begin a correspondence with each other via email, phone or email? Assuming you are willing and have time to help an enthusiastic novice such as myself. I would so greatly appreciate it.
Ill leave my email here if you are willing to help. Daren@kingind.net . Thank you!
@@darenlorenzo8342 I need to point out that this meter is only for water, it concerns me when you wrote about pressurized fluid, because this meter is not for any other fluid, especially not something flammable. This is just a hobby for me, and was geared more for someone who wants to measure water use in their drip system or similar. I don't know your application, but phrases like "emergency stop" seem to hint this might be something that requires a professional programmer / electrical engineer.
This resistor divider drops the voltage to 3.4v. Over 3.3v GPIO limit, is not this dangerous? Or the sensor out not have 5v output? If is 5v, the R2 should be >=9k
where do i find the python code?
Hi, I know this is a water flow sensor but I would like to use it for air, do you know if that's possible? It's just to get an idea of a relationship so it doesn't need to be that accurate. Thanks :)
I don't think it will work. Air would cause it to go WAY past it's design speed. It is very easy to make it start under-counting by a lot. I think in the gas business they use pressure and a fixed opening to measure the amount of flow of a gas. I googled "digital air flow meter" and there are such things.
Yes I tried it on a air compressor and it works. Google for the datasheet and as long as your air pressure / air flow is within the spec it should be fine. I used edge detection to trigger a timer function as I am not measuring the pressure thus not measuring frequency.
Cool program. I am using a for loop that cycles through an array called duration = ["1", "2"......,"9","10"] to represent seconds . I change time_new to time.time() + 1 to count off each second and will have this print a graph of flow each second by printing ******** according to what I need.
That sounds like an interesting update. Post a video and leave us a link.
BTW, I added a comment above with links to 3 other videos on the water meter.
Will this work for gravity flow, with less head pressure ? head pressure is going to be 10 PSIG
The specs are in the description. The manufacturer lists a maximum, but not a minimum. I think gravity would work fine as long as the flow rate is within specs.
Good day
I need help with the code.
I want the flow meter to count 500ml and then then the relay must close?
How can i do that
I put a lot of info in the description. It will be different for each model of flow meter. 500 ml per what time? This meter has minimum and maximum flows. Outside of those it does not work well. Also the accuracy is only ±10% and the range is 1-30 Lpm. Hope that helps.
do you think this could be use to measure airflow in an HVAC system?
Probably not very well. The little turbine starts spinning very fast and it stops being accurate at all. It needs the thickness of the water to dampen it.
Hi, can you explain a little bit more about how you get the constant.
The constant REALLY depends on your code. In theory you can just use your setup to fill a bucket of water and time it. Then use the flow per time info from that to make your constant. That constant will depend on your code.
You can start with the data I put in the description as a baseline.
Thank you for your response. I am basically doing this project to measure consumption on my kitchen sink tap and i did as you suggested and it seem to have worked for the first test but when i open the tap and have water running at the different speed than the one i used to get the constant then i get wrong results. My thoughts are that the pressure or the speed of water affects the time it takes to fill a bucket of water to get the constant, so my question is: is there no way of getting the constant at runtime based on the speed the water is running? forgive me am still new at this.
@@mfundosydwell3713 did you find any solution to your problem?
Hello,
thanks for the nice tutorial video. We are currently working on a project where we maybe want to use a similar flow rate sensor. This is why i wanted to ask you, whether you happen to have a log file of the raw sensor values (ticks or pre computed speed values at some time points). This would allow us to analyse the sensor upfront in order to check whether it fits our requirements. So please send me a log file if you have one, this would help us a lot!
Thank you in advance.
I did not keep the data since I made it during a test. I just blew air through the meter. You can do the same if you want data.
wanted to have a look at the data, before buying the sensor, without knowing whether it's good for us... but thanks for the quick reply!
The data is just 1's and 0's. The faster the water flow, the more 1's you get per minute. Add up the 1's per minute and you get the rotation speed. The meter has a maximum and minimum speed. (It does not give good readings above and below those. I talk about it in the video.)
Would it be difficult to add an LCD module to display the output?
I have not tried that yet, I've seen people who have. It looks like something that's in the "moderately difficult" category.
Thank-you for the informatics video, if you installed it in some permanent location, I would like to know if its still working.
I did it as a test and to help a friend with computer training.
Hi, how can be able to download the code?
Is the min flow rate is 1 lit ? Flow rate I get is around 500ml/min
I put the manufacturer's specs in the description.
Hi
Could the code be modified to only record when water is running
I've thought about that. It's mostly a problem with the sensor. It's a magnet passing by a switch. If the impeller stops with the magnet on the switch (maybe 1 in 20 chance) and it stays there for say 2 seconds, you could set a flag saying it's (probably) stopped. Same if there's no change for 2 seconds and it's off. That seems pretty reliable and simple, but when water flow is slow and the pulse is missed or when it's really fast and the pulse is missed by the pi, it can act like it's stopped. I think it is do-able. I will have to give it a re-think. Thanks for the question.
Hi
I found the following program for testing the hall sensor that reacts very quickly to the on or off of the water flow. The program does not even start until the water flows, but it only returns high or low +time. Is there a way to incorporate this on off feature into your code. I am new to python coding so I maybe talking rubbish but I thought it might be worth asking the question
#!/usr/bin/python
#--------------------------------------
# ___ ___ _ ____
# / _ \/ _ \(_) __/__ __ __
# / , _/ ___/ /\ \/ _ \/ // /
# /_/|_/_/ /_/___/ .__/\_, /
# /_/ /___/
#
# Hall Effect Sensor
#
# This script tests the sensor on GPIO17.
#
# Author : Matt Hawkins
# Date : 03/04/2017
#
# www.raspberrypi-spy.co.uk/
#
#--------------------------------------
# Import required libraries
import time
import datetime
import RPi.GPIO as GPIO
def sensorCallback(channel):
# Called if sensor output changes
timestamp = time.time()
stamp = datetime.datetime.fromtimestamp(timestamp).strftime('%H:%M:%S')
if GPIO.input(channel):
# No magnet
print("Sensor HIGH " + stamp)
else:
# Magnet
print("Sensor LOW " + stamp)
def main():
# Wrap main content in a try block so we can
# catch the user pressing CTRL-C and run the
# GPIO cleanup function. This will also prevent
# the user seeing lots of unnecessary error
# messages.
try:
# Loop until users quits with CTRL-C
while True :
time.sleep(0.1)
except KeyboardInterrupt:
# Reset GPIO settings
GPIO.cleanup()
# Tell GPIO library to use GPIO references
GPIO.setmode(GPIO.BCM)
print("Setup GPIO pin as input on GPIO17")
# Set Switch GPIO as input
# Pull high by default
GPIO.setup(17 , GPIO.IN, pull_up_down=GPIO.PUD_UP)
GPIO.add_event_detect(17, GPIO.BOTH, callback=sensorCallback, bouncetime=200)
if __name__=="__main__":
main()
By the way I tested your code with run of 30 minutes and found it to be very accurate +/- 2%. the only problem is when the flow stops, if it stops on 1 it keeps recording 1s and gives an inaccurate reading.
I am rethinking this. I think it can be done, I just have to go about it in a very different way. First I am going to write a tachometer for it to better understand exactly what it is doing.
As promised I came up with an advanced version that tests for a stopped impeller (in fact more than 1).
th-cam.com/video/3q7simXNlm0/w-d-xo.html
th-cam.com/video/0fqoq1jWlts/w-d-xo.html
th-cam.com/video/wpenAP8gN3c/w-d-xo.html
Can I use the sensor if it is connected to DAQ (Data acquisition)? without using the Pi or arduino.
It's not a smart sensor. It's just a hall effect switch that is triggered by a magnet on the impeller.
Hello,
This unit, can it be connected to control ?
Like Temptron
I do not know temptron, but I have a video talking about using it to control a water system.
@@tsbrownie this device has digital input, can it be connected?
@@listrikb6885 It uses a magnet and Hall effect sensor. The magnet triggers the sensor creating a pulse (or pulses) per revolution. The raspberry pi counts the pulses. Data is in the description.
do the sensor give reading when when the water flow is slow?
The details are in the description. Working Flow Rate: 1 to 30 Liters/Minute
@@tsbrownie so if the flow lower than 1 L/min it wont read anything? am i right?
@@muhammadzar3002 It may or may not read, but it will be inaccurate.
@@tsbrownie thanks for your reply.
Will this code work for a YF-G1 ?
I included the YF-S201 specs in the description so you can compare to others. You should also consider that the electrical requirements may be different.
can you use this flow sensor for diesel or gasoline?
No, these are for water only.
try swissflow meters
Where do you download the software for arduino?
Don't know, never worked with one. Sorry.
jut google arduino IDE
Hello, this version of raspberry pi can work on three water sensor at the same time
Yes, but timing begins to seriously affect accuracy even more.
@@tsbrownie ok thanks, but can you explain more and what is your advice or the best solution if i want to make three water flow sensor works together at the same time.
thank you so mutch you are the best.
@@qatrahqatraty8184 I have not done that, so my answer is a guess. But if I needed accurate results I would experiment using 1 dedicated secondary micro computer for each meter (some in the Arduino family are only 2 USD) and use another primary to gather the data.
@@tsbrownie thanks for the advice i am gonna try it
your video is great, but im having issues on line 23,
print (GPIO.input(inpt), end='') #status indicator
^
SyntaxError: invalid syntax
can you help me? thanks
I think your "end" is incomplete.
What do you mean by incomplete?
@@zackyilahiazmi2073 You either have an error in the previous line OR you have a " instead of ' ' (double quote instead of 2 single quotes)
I recently search about my problem, its because im using python 2 instead of python3, but after i install python3 and use it, it still say invalid syntax at end=''
@@zackyilahiazmi2073 It looks like you are using the wrong quote marks. Use either 2 singles '' or 2 doubles ""
my flow sensor is not reading it when i wrote the pgm and ran like this....cant understand whats wrong...its urgent can u help?
can u upload a ckt diagram for this
@@ishoe7684You need to watch the end of the video. There are labeled pictures of the actual circuit.
I'll try again and update u😊
Hi
Can I use a Level converter (for example www.adafruit.com/product/757) instead of the two resistors?
I missed your comment, youtube does not always send me an alert. I don't know that product so it is not safe for me to comment. Sorry.
can we use water flow sensor to check gas flow sensor??
I am not an expert, but I think that gas flow meters are different.
Are both resistors 4.7K?
In my setup the other is 10k, BUT that varies depending on the voltage supplied, etc. Look carefully and you can see at 08:58
Hi can you send me the code please
What's up man? Well, i'm having some errors.... I bought a water flow mater 3/4", and then I wrote all the code as well, and I'm having the following error:
Run time Error: please set pin numbering mode using GPIO.setmode(GPIO.BOARD) or GPIO.setmode(GPIO.BCM)
What can I do? Anyone can help me?
Sounds like your setmode statement is wrong or commented out or such. Remember they have to be exactly the same including ".", capital letters, etc.)
I've checked out all the code, but there's a little thing that it didn't match:
[...] time.asctime( time[...] and the end of line is cutted off. Could you tell me what is written?
Thanks!
any update on this one?
thanks!
Sorry, just saw your comment. That line is:
print('Time (min & clock) ', minutes, '\t', time.asctime(time.localtime(time.time())),'
')
Yes it is in the works, but my real job is interfering with my hobby! ;) Should be done in a week or so. I will leave you the link here when it's done and before it's made public. I solved the stopped impeller issue.
thanks for your code, but i want know , how to calibration ? , thank you
It depends on your setup. But the basic calibration specs are in the description.
@@tsbrownie in your video , your code constant value 0.10 . Can i know where can get 0.10 ?
@@ilhamahmad6156 It is just a place-holder. If you look in the description I have the manufacturer's data on how many Hz = how many liters / min. BUT you have to adjust it base on your code and how much you have the pi doing.
@@tsbrownie i use water flow meter fs300a 3/4 , i get in 1 liter 4 seconds , so 60/4 = 15 liter / min , so in my water flow meter , F = Q * 5 , so i get value frequency is 75 , is this true ?
@@ilhamahmad6156 I do not know that meter. You have to get the information from that manufacturer.
How can we download the code for this project?
This is just a hobby thing. I don't have a web site.
I sent you a private message
please reply when able.
I have 3 new flow sensor videos, each has benefits:
th-cam.com/video/3q7simXNlm0/w-d-xo.html
th-cam.com/video/0fqoq1jWlts/w-d-xo.html
th-cam.com/video/wpenAP8gN3c/w-d-xo.html
how does one learn these commands and tricks? i want to keep track of how much beer is being poored from my kegorator
cdn-learn.adafruit.com/downloads/pdf/adafruit-keg-bot.pdf?timestamp=1549498574
why isit not working only for me :( :(
Check your wiring and code carefully. Small things are important.
ur total is wrong. you didnt blow 12 liters of air through that. you aren't integrating right.
Yes I said that in the video. The problem is that impeller is spinning very fast giving wrong measurements. This was made to measure a relatively viscous fluid (water). Also the specs show it has limits on upper and lower impeller speeds. This was just for demonstration purposes.