I am working on setting up a plant watering system (the plants are ones that are legal to grow), and I am trying to figure out what options I have. I have 9 plants currently, and looking at potentially expanding to 16 plants, and they are all in a row. What I want to do is have a capacitive soil moisture sensor in each plant, and the readings from that can be used to turn on a water pump and open a solenoid valve. I am still deciding on which Arduino board to operate this.
I would like to try doing this on I²C and daisy chain modules instead of having individual cables running to each plant (otherwise I could have bundles of 32 wires at times). I am looking at using the STEMMA I²C Capacitive Moisture Sensor, but there are only four available I²C addresses available. I was thinking that I might be able to use some addressable I²C STEMMA modules to read up to 16 sensors at once, and I think the LTC4316 I2C Address Translator might work for this. Before making any purchases though, I wanted to see if this is my best option or if there are other modules that I can daisy chain together that would work better.
I am also hoping that I can daisy chain together some I²C modules that I can use to power a solenoid valve at each plant (either by connecting to a relay that powers the solenoid or directly powering the solenoid). Are there any options available for this?