I own two DC OS hw 2.3, FW 2.1.7
I use one to irrigate a large swat of land, where there is no aqueduct and the water is coming from a water well that fills a 6 cubic meters reservoir.
It’s critical to monitor how much water is in the reservoir, as it depends on the season and how much water the well can supply.
I managed to make a very accurate level sensor by using an engineering-grade, high quality, high accuracy pressure sensor. For 60 bucks this little device measures a pressure with 15 psi end of scale, it’s powered by 12-24Vcc, and returns a linear output from 0 to 5.000 volts. It’s very accurate and can appreciate 1cm variations (email me privately for the link, to which company I have absolutely no connection beside being a happy customer).
Now I am monitoring the water level by having an IP camera looking at a digital voltmeter, which I calibrated with a potentiometer to have the digits match the liters in the reservoir.
I already use the single sensor input of my OS 2.3 to measure the irrigation flow and volume. I would buy the OS 3.0 with dual sensor input in a heartbeat, if it supported a continuous, calibrable volt signal in the second sensor input, even if just to show it in the app and send it via IFTT email. Then it would be even better if it could be set to interrupt the irrigation if the voltage (reservoir level) went below a certain threshold.
Just a suggested feature for a future firmware, somebody else may need that.
Why not read the output voltage with a device containing an ADC (an arduino for example) and have that device control the station through the OS API? I would think it quite possible to have an arduino or some other device read the output of your sensor and then send the HTTP commands to the OS to manipulate the station/program.
@Nicola: the two sensors on OS 3.0 are both wired to digital pins so they won’t actually read analog signals. As Mike suggested, you can use an ADC module (for example, something like PCF8591) to read signal from your analog sensor, and hook up the module to the I2C interface on OS 3.0.
There is one ADC pin on OS 3.0 — but that’s already wired to the solenoid current sensor.
OS 2.3 actually has several spare analog pins (those are all named Axx where xx is the pin number). The analog pins can read your analog sensor values.