Ok, since I received my Arduino, I have been playing around with some simple projects in an effort to understand more about the way the Arduino board works, and to gather some of the basic electronic skills necessary to work with it. So now, I want to turn my attention to something a little more in tune with my reasons for actually buying the Arduino in the first place: home automation.
After a trip to the gas meter cupboard, unfortunately my gas meter is not the type that outputs a digital ‘pulse’ at regular intervals: it’s an odometer type. However, usefully, I did discover that it has a little reflective disc between the digit ‘6’ and ‘7’, which could presumably be read with some kind of reflection sensor. I did some digging around to see who else on the web has built their own gas-meter readers, and found BWired.nl. This is an awesome site – certainly way beyond what most of us mere mortals could aspire to for our home automation setups! Anyway, on this page, the owner describes using a ‘CNY70 Reflective Optical Sensor with Transistor Output’. After some digging around, I found that Maplin has something which (I think) might be similar here – it’s called “Photoreflector SY-CR102” and it costs £0.79! This neat little device includes a photo-emitting diode and a phototransistor, which should do the trick.
I’ll go down to the store and pickup the Photoreflector later today, and have a go at playing with it over the coming days. Essentially what I need to do is figure out how the sensor responds whenever the reflective disk of the gas meter passes the sensor aperture. In theory then, at least, it’s then going to be a case of simply counting the ‘pulses’ from the sensor. Once I can do that, given that the dial will rotate once a known quantity of gas has been consumed, I should be able to create a very accurate sensor device that is synchronous with the gas meter itself.
Here’s how I imagine the project to unfold:
- Part 1: planning (you’re here!)
- Part 2: connecting the phototransistor to the Arduino, and experimenting with creating a pulse counter
- Part 2a: building a prototype sensor ‘bar’ to connect the phototransistor to the gas meter
- Part 3: connecting the Arduino to the gas meter and capturing the data
- Part 4: transmitting the data back to the PC (for this I’ll probably use an Ethernet Shield so I can send packets of data back to a client app)
I’m quite excited about this – it’s such a steep learning curve though! 🙂