Impulses generated by an infrared sensor detecting the revolutions of a ferraris disk based electricity meter are published with MQTT and are also displayed on a simple embedded web page. As visual feedback the blue LED on the Wemos D1 mini board will blink if the red marker has been detected. Meter values are frequently saved to EEPROM to migate counter resets due to possible intermediate power failures.
- Wemos D1 mini development board
- TCRT5000 IR sensor board
- 5V (250mA) Power supply with micro USB plug
Since the low/high impulses generated by the widely used TCRT5000 sensor on D0 are not very reliable (e.g. multiple counts for single pass of the "red marker" on the ferraris disk) its analog output (A0) is used to automatically determine a suitable threshold value to detect the marker. This way you don't need to fiddle with the small potentiometer on the sensor board to find the "right" trigger threshold for your specific sensor mounting setup.
Set the WIFI_ and MQTT_ defines at the beginning of the sketch. The value for
TURNS_PER_KWH must match the value printed somewhere on your electricity meter
Uncomment LANGUAGE_EN for an english web UI and serial debug messages.
Add support for ESP8266 based boards to your Arduino IDE using the boards manager.
Before trying to compile and flashing the sketch to the Wemos D1 R1 board make
sure that the following libraries have been installed using the
Arduino IDE library manager:
Connect the 5V pin of the TCRT5000 sensor to 3.3V pin (not 5V!) of the Wemos board and its ground pin to GND. The analog output of the TCRT5000 sensor (A0) must be connected to the corresponding analog input (A0) of the Wemos. The Wemos can be powered with a small USB power supply (5V, around 250mA).
After powering up the Wemos D1 mini it should connect to your Wifi network and receive an IP via DHCP (check your router or the serial debugging messages). Point your favourite browser to the IP. If you see the embebbed web page you can proceed mounting the sensor and the Wemos on your ferraris meter.
For mounting the TCRT5000 on your ferraris meter a little 3D printed case comes in handy. Thingiverse offers quite a few options like this one
Since this sketch also supports OTA-Updates of the firmware, you only need to flash your ESP8266 once before mounting in your meter cabinet.
Make sure that during the initial calibration phase of READINGS_TOTAL_SEC
(default 90 secs.) triggered by Calculate Threshold the ferraris disk is actually
spinning fast enough. The calculation of the threshold should be based on at least
two full revolutions with the red marker passing the IR sensor twice. Turning on
your oven should help to speed up things. ;-)
After the initial and hopefully successful calibration cycle you only have to
save the calculated threshold value with Save Threshold to switch the Wifi
power meter to normal operation. You can later tune the threshold value with
http://<IP>/setThreshold?value=XX.
The initial offset to your current electricity meter reading needs to be set once
with the following command http://<IP>/setCounter?value=XXXXX.X after setting the
threshold value. Then you're ready to go.
The Wifi power meter offers support for RESTful HTTP requests. Current readings are
available as JSON under http://<IP>/readings. See restful.html as an example.
For debugging purposes you can continuously send the analog readings (every READINGS_INTERVAL_MS)
to an InfluxDB with UDP.
Contiously visualizing the readings with Grafana
might help placing the TCRT5000 on your electricity meter to get better IR readings.
Pull requests are welcome! For major changes, please open an issue first to discuss what you would like to change.
Copyright (c) 2019-2021 Lars Wessels This software was published under the MIT license. Please check the license file.