I need help with my university project. I have a very vague idea of the project but i feel like i am still out there in the dark.
For this project we have been asked to measure the moisture level of the soil with the help of a soil sensor. The readings from this sensor must be transmitted to a computer to check the moisture levels at different times. When the soil sensor detects that the moisture level is insufficient it must activate a sprinkler based system to water the plants. And this sensor must deactivate the sprinkler based system when it detects that the moisture level is insufficient. All this activiating and deactivating of the sprinkler based system must be done wirelessly. We have been recommended to only use one or two soil moisture sensors each connected to a wireless sensor node?!
Please make a note this project will be done on a small scale!
what components would you recommend for doing the following jobs and why?
1.Microcontroller for programming the soil moisture sensor and maybe a temperature sensor?
2.Which soil Moisture sensor?
3.Which temperature sensor?
4.What type of wireless modules for transmitting between the soil moisture sensor module to the module that will activate the sprinklers?
5.How should the system be powered?
6.What kind of solenoid or motor component to pump water?
7.What kind of kit to place the soil sensor and the temperature sensor attached to the microcontroller into the soil? Or would you recommend wireless soil moisture sensors and temperature sensors?
8.What kind of software program will we need?
9.Any other components you think we will need?
How would recommend bringing the project into play: by placing the sensor modules into potted plants? or using a strip of field? or anything else?
4.What type of wireless modules for transmitting between the soil moisture sensor module to the module that will activate the sprinklers?
Depends on your needs, ZigBee is a possibility, bluetooth probably the better and cheaper alternative.
5.How should the system be powered?
That question is being returned: Do you have a wall plug available? If yes, use it! Else you have to go with batteries and let your system sleep most of the time.
8.What kind of software program will we need?
Your own :-).
Your bugdet budget is probably enough as I was using less money to build my system (two small indoor fountain pumps and a relay for each, two temperature sensors and two moisture sensors together with an Arduino were under 200 bucks), although my system has no wireless transfer. You probably don't need the wireless connection as a cable between the systems is much more reliable.
Thank you for the help i will look into the components you have suggested! I would have used a cable but the instructors have asked us to do it wirelessly!
I have done something similar using a couple of stainless steel cooking skewers as a resistive moisture sensor, a 3-12V micro pump costing about three quid, and a couple of RF24 radio transceivers costing a couple of quid each. This is used indoors and is mains powered. The controller is completely self contained and only uses the RF link for logging and to raise alarms. Running the pump off a battery would not have been practical in this case.
This only supplies a small amount of water, though. If you're planning to water a large area I suspect you'd want to have one or more remote moisture sensors notifying a central controller that decides how much water is required and controls the pump or solenoid valve to supply it. RF24 transceivers would be a reasonable and very cheap solution for this, although the range is not great so if this is for large scale use you'll need something more powerful. In this case I suggest you measure moisture a couple of inches underground rather than at the surface, and average it over several hours before deciding how much water to apply.
I have decided to use the Ecoduino since nmy project only requires to be built on a small scale! It has innuilt humidity and temperature sensor? but taking these readings how will it help me?
But thing is i dont understand what threshold should i set the soil moisture sensor to for the immersible pump to start watering the plants? How deep in the soil should the sensor be placed?
Since the project has to built in college i was thinking of bringing a kid of large tray and growing grass and then putting the sensor into the mud and monitoring the soil moisture content but i dont know how deep should the tray be? is there any particular level of threshold i should set? does it matter?
If it's for a project then you might consider using a potted plant rather than trying to grow grass from seed.
I suggest you should try to monitor the water at about the same depth as the plants' roots.
You need to know what soil moisture level suits the plants best and then find out what that reading corresponds to on your moisture sensor.
It took me quite a lot of trial and error to find what probe size/position, resistance and measurement timing gave me the best sensitivity for moisture within my target range. The blogs I'd read beforehand didn't give the impression that this measurement technique was as fiddly as I found it to be, but it does work OK now. My sensor consists of a couple of 1/8" diameter stainless cooking spikes 6" long. The spikes are insulated except for the bottom 1/2". I've secured them in an electrical chopblock connector to hold them about 1/2" apart. I forget what resistance I ended up using but I think it was about 5KOhms. My measurement technique is to keep the sensor powered down most of the time; to take a reading I power the sensor up and wait 5ms then measure the voltage across the sensor. After taking the reading I apply a reverse voltage for the same interval to counteract any ionization effects. The length of the delay before taking the reading affects the reading, presumably due to ionization, but in my case this value (5ms) seemed to give a reading that correlated best with changes in the coil moisture within the range I'm measuring. The readings are a bit variable and I take one sample per second and average over a minute before deciding how much water to apply.
Getting the hardware and software basically working is easy. Getting them calibrated and configured to actually control the moisture at the target level was much harder. You'll need to play with it to see what works best for you. If you only need to show the design and demo a prototype, that part may not actually matter for you.
I would have used a cable but the instructors have asked us to do it wirelessly!