Example of connecting a Sensus 620 water flow meter to home automation The goals was to link the flow of water to a Home Automation system. Domoticz was used but that could be HomeAssistant as well.
- NodeMCU V3 from Lolin
- Inductive sensor, measures the presence of metal in the spinning disc indicating the liters
- 12 Volt 2Amp switching power supply
- Breadboard, wires, Resistors, capacitor
- 2 basic diodes
- BC550 transistor
- Metal strip with hole to mount the sensor in
- Tire wraps to strap the metal to the watermeter
After a bit of tinkering this was the end result:
Things to explain:
- The Vin pin should be able to deal with 16 Volt.. but I've seen comments on it that it can break the board. That is why 2 Diodes were added to lower the voltage at Vin with 2 x 0.6 Volt
- Using a general purpose BC550 worked well. Measurements on the voltages and testing with metal to create pulses gave the resistor values. Note that the sensor voltage will destroy the NodeMCU input if higher than 3.3 Volt
- By Using this sensor, it would not rely on reflection of Infra Red light but use the metal disk in the spinning meter. It indicates 1 liter used with one turn.
EasyESP combined with the NodeMCU is a very easy way to connect sensors over WiFi to your home automation. Details on the binaries were (and may still be) on this page: https://www.letscontrolit.com/wiki/index.php/ESPEasy However an update page seems to be here: https://espeasy.readthedocs.io/en/latest/index.html A generic tour of the web interface on the flashed device is here: https://www.letscontrolit.com/wiki/index.php?title=ESP_Easy_web_interface Do not expose the web interface to the internet and look into the configuration of trusted segments in your LAN, meaning the device will only accept 'friendly' connections.
To flash the EasyESP firmware, the NodeMCU firmware flasher was used but setups work different for you. Current documentation seems to suggest other options for the ESP32 platform as well.
Here are the settings and screenshots from the NodeMCU firmware flasher:
The details of the version used:
Start screen:
File selected to burn into the NodeMCU:
Settings for burning process.. important to follow the SPI mode and flash speed.. there are cases where the Wi-Fi on the NodeMCU would not start if done otherwise:
Final screen anfter successfull write (data deleted in picutre):
After the programming is done, reset the power to the NodeMCU and:
- search for an ESP_Easy_0 Wi-Fi network. The NodeMCU will create that network and it awaits to be configured via a browser.
- Password is 'configesp' to get connected
- Browse to 192.168.4.1 (may work different per browser Safari and Chrome worked, also iPad and Android phones were successfull)
- the wizzard will start, only set the credentials for your local Wi-Fi. Once done, reset the device. It will try and connect to your Home Wi-Fi
- After reset it will appear on network if all works fine (it needs that reset to restart the Webserver interface)
If you reached this point, then it is time to start setting up Domoticz because we need to get a device number for the Waterflow sensor first.
Like mentioned at the start of the article, Domoticz is used. Eventually it will look like this:
The start of a successfull installation is the creation of a virtual sensor via the Domoticz hardware list.
For that to work a virtual device should be made first for the ESP-EASY sensor(s).
Then create the virtual sensor and be sure to use an incremental counter:
Once created, click modify to set the parameters correctly and to offsett the measured value. The sensor will start at 0 but your real-world water meter probably has another value on the counter. This is the place to align/ offset the counter so they are in sync. Also, note down the IDX number of the virtual sensor. This is needed in ESP_Easy software so the watermeter data can be posted to the right Domoticz sensor.
Go back into the web Interface of the EasyESP to finalize the setup of the sensor. We need to tell the device where to post the data and the sensor must be configured to the correct input of the NodeMCU. When logging on, this should be a similar view in the 'Main' tab:
Step into the 'Controller' tab to set the ip address of the Domoticz instance in your LAN. Check the controller port since it may vary. 8080 is the standard Domoticz port number but it can be changed if your site requires that. Note that the protocol has a nice drop-down selector so no typing errors here.
Set the D5 port (=GPIO-14) as input:
And set these to have the correct LED functionality:
Almost there.. time to add the Sensor as device. Select the generic device 'pulse counter':
After creation you can edit the hardware:
In the next screen the IDX and characteristics like 'Rising' edge counter can be set. Do take notice of the debounce time, this value works fine for the setup here and there was not a liter miscounted during the runtime that it has had.
Done!
Note that the sensor is positioned off-center of the spinning indicator. Otherwise it does not create pulses but 'sees' the metal all the time.
With EasyEDA a PCB was made. Never used it but in 2 hours including learning curve, the board was ordered.
I did use KiCAD before but this was also really easy. The software knows a lot of components and footprints.
(I later discovered that the solder pads are not large enough and the ground plate fill is giving problems.. learning by doing. Next version will be better)