The postman brought an exciting package yesterday morning:
An SD card module, a liquid crystal display, some bits of wire, and a tiny little Arduino Nano computer (copy)
This meant that, first and foremost, I could replace the borrowed computer in my solar controller, and solder it all together so the wires aren't so prone to getting knocked out of their sockets. If possible, I'd like to use the little piece of strip board that I already have, rather than buying any more (yes, I am that tight with money). This makes the design quite tricky, as there's not much space to play with. I took a photo of the existing circuit...
... and edited it.
Having got this far, I checked which Arduino pins I'd need for the SD card and LCD, and moved things around a little to free those up. This morning, I took a hacksaw to stripboard, heated up the soldering iron (I was going to write,
Got out the soldering iron, but in all honesty, I never put it away), and applied solder as per plan. After moving things around, I found that I don't need the cut off piece of stripboard yet, but I will later.
I'd like to have the sensors on plugs, so that I can unplug them if I need to take the controller out of the cupboard, for example to add extra bits. For the time being, I have short leads soldered to the board and I've twisted wires together to attach the sensors.
It's all connected up now and it seems to be working. The pump came on as soon as I switched everything on, but that's what I'd expect if there was no signal from the controller*. The real test was whether it would switch off when required. After toying with the idea of taking the glass off the panel to cool it down, I made myself a cup of tea, then took the tank sensor out of the tank and held it against the hot cup. A much more sensible test, and it worked. After that, it clouded over, so I didn't get to hear it switch on again, but so far so good. I'm now studying how to add the display and SD card, so I'm afraid you haven't seen the last of these posts.
* I've wired it up to default to
onto give me a manual override. If I plug the two parts in separately, I can switch the controller off and the pump on, if I want to. Obviously, I could also switch both off, if necessary