Water Level Monitor Node, Type 2 Nov 25, 2016 22:46:57 GMT
Post by papa on Nov 25, 2016 22:46:57 GMT
Water Level Monitor Node, Type 2
Thread Updated April 5, 2019
for openHAB 2.5.0.M1, MQTT 2.x Binding, & the Embedded MQTT Broker
Today I finished building, programming, & installing a Type 2 RFM node to monitor water levels (in my case, still within my sump pump hole).
With the "type 1" node (which I documented as "Sump Monitor Node"), an ultrasonic sensor at the top of the sump hole uses ultrasonic sound waves to measure the distance to the water surface. So far this node (& the OpenHAB programming), basically works to measure & signal safe levels, & levels that are too low (pump stuck on) or too high. Not too many connections are required to build the node. While this node is serving its purpose, readings from this node bounce around a lot (I guess because of the "fuzzy" surface of trickling water in the sump hole).
For the "type 2" of a node to monitor water levels, probes are placed at various levels in the water container & when the probes are covered by water, transistors amplify the probe's output for the Arduino program sketch to read. On the internet, you may have seen the many examples of this principle being used to directly light LEDs according to the water level. I've seen a couple examples of an arduino type device controlling this monitor. In fact, I adapted a schematic & a program sketch (provided below) which I used to test the water level reading ability of the basic principle. Once that was working, I installed an RFM69 radio on the node & added the water level code to my Multi-Choice End Node version (also provided below) of the computourist end nodes.
So far, the type 2 water level node signals straightforward changes in water level status (not bouncing around like for type 1). Since electrified probes like for type 2 can supposedly corrode faster due to electrolysis, my design uses an Arduino digital pin (d7) to power the probes briefly every 60 seconds just before the water level status is sent via the gateway & then power to the probes turns off. Because this type 2 method measures one less level than the number of probes (because the lowest probe is "common" to the others), a limited number of levels are measured (Besides the common probe, I use 3 other probes which require 3 Arduino pins plus the pin to power the probes.) Building the type 2 water level node is more challenging (See the schematic below): The four probes all connect to d7 that powers them. The three transistors each have 3 pins & each of the 3 pins have 2 or 3 connections to them. As for type 1, the water level status that the node sends to OpenHAB can be massaged to use dynamic icons to visually display the status.
Both types have advantages & disadvantages. I will let them operate side by side & see how they compare.