View source for Temperature monitoring with Dallas DS18B20 sensors and Domoticz



== Sensors ==
We use the [https://datasheets.maximintegrated.com/en/ds/DS18B20.pdf DS18B20] sensors, pre-mounted into a waterproof flange from the [https://www.brewpi.com/ BrewPi project]. These have RJ11 (6P4C) connectors pre-crimped, which we replace with the more common RJ45 (8P8C) connectors and extend the cable with a standard CAT5e FTP (or STP) cable. The connections are similar to the the common T568B color coding and the follow the 802.3af (Power Over Ethernet / POE) with respect to the DC +/- colors.

=== Sensor Pinouts ===
[[File:Rj45plug-8p8c.png|200px|thumbnail|right|Pin numbers on an 8P8C (RJ54) plug.]]
{| class="wikitable"
|-
! Pin number
! T568B color
! colspan=2 | 10/100 mode B, <br/>DC on spares
! RJ45 connector (8p8c)
! DS18B20 <br/> flange-cable color
|-
! Pin 1
| [[File:Wire white orange stripe.svg|60px|Pair 2 Tip]]<br/> White/orange&nbsp;stripe
| Rx + || 
| NC (I2C SCL)
| 
|-
! Pin 2
| [[File:Wire orange.svg|60px|Pair 2 Ring]]<br/> Orange solid
| Rx − ||
| NC (Analog)
| 
|-
! Pin 3
| [[File:Wire white green stripe.svg|60px|Pair 3 Tip]]<br/> White/green&nbsp;stripe
| Tx + ||
| DATA (I2C SDA)
| [[File:Wire white.svg|60px]]<br/> White
|-
! Pin 4
| [[File:Wire blue.svg|60px|Pair 1 Ring]]<br/> Blue solid
|  || DC +
| +3.3V
| [[File:Wire red.svg|60px]]<br/> Red
|-
! Pin 5
| [[File:Wire white blue stripe.svg|60px|Pair 1 Tip]]<br/> White/blue&nbsp;stripe
| || DC +
| +3.3V
| [[File:Wire red.svg|60px]]<br/> Red
|-
! Pin 6
| [[File:Wire green.svg|60px|Pair 3 Ring]]<br/>Green solid
| Tx − ||
| GND (- for data)
| [[File:Wire black.svg|60px]]<br/> Black
|-
! Pin 7
| [[File:Wire white brown stripe.svg|60px|Pair 4 Tip]]<br/> White/brown&nbsp;stripe
| || DC −
| DC - (for power)
| [[File:Wire black.svg|60px]]<br/> Black
|-
! Pin 8
| [[File:Wire brown.svg|60px|Pair 4 Ring]]<br/> Brown solid
| || DC −
| DC - (for power)
| [[File:Wire black.svg|60px]]<br/> Black
|}

{| class="wikitable"
|-
! Pin number
! RJ11 connector (6p4c)
! DS18B20 <br/> flange-cable color
|-
! Pin 1
| empty (no contact)
| 
|-
! Pin 2
| not connected
| 
|-
! Pin 3
| Vdd (+3.0V — +5.5V)
| [[Image:Wire red.svg|60px]] Red
|-
! Pin 4
| GND (-)
| [[Image:Wire black.svg|60px]] Black
|-
! Pin 5
| DQ (DATA)
| [[Image:Wire white.svg|60px]] White
|-
! Pin 6
| empty (no contact)
|
|-
|}

== Development Progress ==
=== Part 1: Fixed installation - 8 temperature sensors per ESP ===
In this part, we want to attach as many DS18B20 on one ESP as possible, with the circumstance, that the sensors are up to 40 meters apart from each other.

==== GPIO pin assignement ====
The NodeMCU has it's own [https://raw.githubusercontent.com/nodemcu/nodemcu-devkit-v1.0/master/Documents/NODEMCU%20DEVKIT%20V1.0%20PINMAP.png designation of pins] for the ESP8266, just like the Arduino has for the ATmega328. 

We use '''D0 - D7 as digital inputs''' for the ''1-Wire'' connection to the DS18B20 temperature sensors.
D8 can not be used for ''1-Wire'' devices, because the ''1-Wire'' bus needs a pull-up resistor and the D8 is GPIO15 on the ESP8266, which needs to be LOW at power-on or reset, otherwise the controller will not boot.

==== Cable length testing ====
[[Image:ESPeasy-DS18B20-flanged-20m-test.jpg|thumb|100px|right]]
The first sensor with 20 meters CAT5e FTP (unshielded) cable and 8p8c (RJ54) connector and socket (for PCB) works, when connected to ESPeasy.

==== Production ====

The PCB was produced in the CNC. The parts were hand-soldered and covered with conformal coating (4 layers of acrylic spray). The PCB was installed in an outdoor rain-proof enclosure, together with a 5V/1A USB power supply.


=== Part 2: Valve control - 4 Sensors and 4 Relays per ESP ===

In this part, we need to monitor 4 temperatures and control two valves, which are operated with an electric motor. Each motor is operated by 220V and has an internal end-stop switch, which breaks the circuit at the correct motor/valve position, as well as returns the 220V on a feed-back contact to signal successful operation.

==== 220V circuit ====
[[File:Valve_controller_220V_circuit.png|thumb|100px|right]]
The electric motors can also be energized by manual override buttons, one to open and one to close each valve. The automatic control is done by one SSR (Solid State Relay), which is used for the state of the motor (ACTIVE/INACTIVE) and one electromechanical relay, which is used for the direction (OPEN/CLOSE).