I've been fiddling around with a water meter as well and this is how I did it:
I've bought the following items:
1. A small pcb (sku213567) to which I can hook multiple TCRT5000's. This PCB has 4 separate signal outputs so hook up to 4 GPIO inputs whereas you only need 1 VCC and 1 ground. I do not own a Piface (yet) but I wanted to figure out how everything works.
I know that measuring is much easier via the piface
.
2. Multiple TCRT5000's (sku171350):
you can also buy these (sku213949):
The difference between these two is that the latter is normally closed (so contact shows closed when light not reflected) whereas the first one is normally open (so contact shows open when light not reflected). Kinda depends what you want to do with them.
Once I had the GPIO working, it was time to write a script that counts the usage. It really depends on your water meter what the formula in the script should be. The water meter in the screenshot above has several dials and one of those spins 1 time per liter (the one on the top right has scale x 0.1, so 1 revolution per liter).
First I set the water meter divider in the setup to 1000. Then, I wrote this script (there are a lot of print statements, but this shows what's really going on).
What the script does is:
- Retrieve the svalue from the water meter
- In the event of a pulse from the TCRT5000 via the GPIO port, add 1 (liter) to the svalue
- Write the new svalue to the device
I hope it's useful for somebody
.
Code: Select all
commandArray = {}
print('> Monitoring water consumption')
-- Water usage
-- Retrieve value from water meter device:
sWaterUsage = otherdevices_svalues['Water']
-- To have a better readable format, divide number by 1000:
sWaterUsagePrint = tonumber(sWaterUsage / 1000);
-- calculation is done with the unmodified water value
sWaterUsage = tonumber(sWaterUsage);
print(">> Utilities: Water usage until now is " .. sWaterUsagePrint .. " ");
if (devicechanged['GPIO_WATER'] == 'Close')
then
sWaterUsageTot = (sWaterUsage + 1)
print(">> Utilities: Water usage is now " .. sWaterUsageTot .. " ");
commandArray['OpenURL']='http://IPADDRESS:PORT/json.htm?type=command¶m=udevice&idx=164&svalue='..sWaterUsageTot..''
end
return commandArray
