In my case, I had power nearby, so my build is just a USB-powered ESP32 + LIS3DML in a little box I taped to the back of the meter body. Love this Francesco’s clever methods of saving power. I count the “breaths” and periodically send the count of them off to an Influx db for later visualization. (My meter is American Meter AC-250, really common internal design that probably hasn’t changed much in 100 years). As the steel bellows in the meter expand and contract like lungs, they sinusoidally alter the magnetic field detectable outside the box. It’s not necessary to rely on a magnetic coupling. Posted in ATtiny Hacks, home hacks Tagged attiny, attiny13, ESP8266, gas meter, hall sensor, IoT, plotly Post navigationīy some cosmic coincidence, I happened to just make a very similar device this week, built around a LIS3DML magnetometer. If you are unfortunate enough to have an even older meter which doesn’t use optical or magnetic rotation sensing, you can use a disassembled mouse to keep track of the Gas Meter. Since the data visualization requirements are pretty basic, he is keeping things simple by using Plotly to display his time series data. Overall, this whole scheme allows to reliably gather his gas consumption data while not having to worry about batteries until he gets the low voltage notification. Then at midnight, the ESP transmits all the collected data to a remote server. Battery voltage is also measured via a voltage divider connected to the chip’s ADC pin.Īt regular intervals throughout the day, the ESP8266 polls the ATtiny13 to pull the stored sensor pulses and voltage measurement. The chip doesn’t run continuously, its watchdog is set at 1 Hz, ensuring that the device is woken up often enough so that it has time to power up the sensor and detect the presence of the magnet. For one thing, he uses an ATtiny13 to actually read the sensor values. With the clever use of commonly available parts, he was able to reduce power consumption allowing three AA batteries to last about a year between changes. With some hacking, he was able to attach an external Hall-effect sensor to pick up this magnet and use the signal to monitor his daily gas consumption.Ī big stumbling block in such projects is the issue of powering the device for an extended period, and remembering when it’s time to change the batteries. His meter might not have an LED, but it did have a magnet attached to the counter disk which activated an internal hall sensor. That’s exactly what had to figure out while developing the non-invasive gas tracking system he calls ESPmeter. ![]() But what do you do if your meter isn’t so cooperative? To make things easy, most modern utility meters have a pulsed LED output, which can be used to monitor the consumption by using an external optical sensor. Measuring the usage of domestic utilities such as water, gas or electricity usually boils down to measuring a repetitive pulse signal with respect to time.
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