This week was a bit frustrating trying to get the controls in the greenhouse. First I had to spend a day debugging the arduino IDE. It would occasionally work, then stop, then start… The problem was I have two different sets of arduino nano boards, some of which need the new bootloader option, some of which need the old boot loader option. Second, the 3 way solenoid valves I ordered were not actually 3 way valves but just had an extra hole connected to supply. But it doesn’t really matter because the orifice inside of them is tiny. That’s probably ok for filling up an air seal, but not good for letting out the pressure unless I had a vacuum. So I ordered a motorized ball valve, 1/2”. Should provide a nice large opening.
I tested the load cell, which was super stable on my desk. Very low drift, 2 g/hr. But then I built a rig to weigh a tray and suspended it from the greenhouse ceiling and drift was all over the place. I think the main problem here in retrospect was that it was pulling off axis. I might redo it in a more typical S shape. The other option is to put 3 load cells under each tray. That’s more expensive but the temperature should be more constant so maybe worth it. It also frees up space in the canopy which is good for light modeling.
I also had to revise my plan for microcontrollers. I got the arduino talking to a python script, but it’s just not that reliable. I like it for data logging and sending manual updates, but I don’t want to have anything mission critical like heating or irrigation or venting go from arduino to laptop filesystem to arduino. I want it all self contained in the arduino. So I had to order an arduino mega which has enough pins. I also found that adding extra cable to the i2c humidity and co2 sensors won’t work, too much interference/capacitance. So the arduino has to be in a watertight box in the greenhouse close to those sensors.
Lots of issues. But I did get all the pumps and fans wired in ready for a 5 volt control signal and lots of the pumping is done from the fertigation reservoir.
Sun Aquasystems 