Basic temperature tracing with wired sensors (for air, liquids, ground, etc.)

Manuel Fegerl 03/05/2019
Wifi temperature monitoring with DS18B20 sensors - Easy to build yourself (DIY) without soldering with iOS and Android App for NodeMCU ESP8266

Introduction

With the help of this guide you can measure several temperatures (wired, in air, water and even in the ground). The data is transmitted via WiFi to your smartphone (Android and iOS) and helps you to monitor e.g. your hot water tank, your garden house and much more. This project uses a NodeMCU Amica v2 (based on the ESP8266 microcontroller) and two wired DS18B20 sensors. The current measurement data is also shown on the OLED display. A screwdriver and possibly a side cutter are required to connect the sensor cables.

So that you don’t have to program yourself, you can simply copy the Sensate firmware to the microcontroller, at the end of the manual you will learn more about it. With the help of the Sense App you can access your data easily and at any time (and from everywhere) and see e.g. the daily course of the temperatures.

Typical applications for this project:
– Temperature monitoring in the boiler (hot water tank)
– Temperature monitoring buffer tank
– Temperature monitoring for solar systems
– Temperature monitoring in case of frost hazard (small animal enclosures such as henhouses and harehouses)
– Temperature monitoring for ground temperatures e.g. for reptiles in open-air enclosures


Component list

1
Breadboard (z.B. 400 Pin)
1
NodeMCU Amica v2 (Bridge)
1
1,3 Zoll I2C OLED Display
1
Jumper wires
3
Screw terminal (3-Pin)

Best used with

Quick configure with

Tools and skills


Connecting the bridge to the breadboard

Take the broadboard and bridge as shown and put the bridge on the red marked skirting boards. Please make sure that the USB port of the bridge is pointing downwards. The bridge must then be plugged into the pins labeled as follows:

– Left pin header: a: 16 to 30
– Right pin header: h: 16 to 30


Connect the screw terminal (for the sensor cable) to the breadboard

In this step, the screw terminal (in which the sensor cables are later screwed on) is connected to the plug-in board. The 3 pins are plugged in to j: 8,10,12. Make sure that the opening for the cables is on the right side.


Connect the resistor to the breadboard

The resistor is a so-called pull-up resistor with a value between 3 and 10kOhm. This resistor is plugged between the positive supply voltage and the data cable of the sensor cable, i.e. g: 8 and g: 12, the alignment does not matter.


Connect the display to the breadboard

Now the display follows. The display must be aligned so that the pins are on the right. These are then plugged into the breadboard f: 4 to 7.


Connect display to bridge

Here the display is connected to the bridge. This supplies the display with power and connects it to the data pins D2 and D1 (I2C Bus) of the bridge. For this a cable is plugged in as follows:

h: 4 to j: 21 (corresponds to label 3.3V on bridge)
h: 5 to j: 22 (corresponds to GND label on bridge)
h: 6 on j: 17 (corresponds to label D1 on bridge)
h: 7 on j: 18 (corresponds to label D2 on Bridge)


Connect sensor screw terminal with bridge

Here the screw terminal – which connects the sensors later on – is connected to the bridge. For this purpose a cable is plugged in as follows:

h: 8 to i: 4 (corresponds to 3.3V on display)
h: 10 to i: 5 (corresponds to GND on display)
h: 12 on j: 20 (corresponds to label D4 on bridge)


Connecting the sensor cable

In this manual, 2 sensor cables are connected in parallel. The wires of the two sensors of the same color are clamped into the respective terminal with a screwdriver. Make sure that you do not inadvertently clamp the coloured insulation, otherwise malfunctions may occur.

j: 8 – Red cables (positive power supply for sensors)
j: 10 – Black cables (ground for sensors)
j: 12 – Yellow cable (data line of the sensors)


Result

If your microcontroller (bridge) has not yet been loaded with the Sensate firmware, follow these instructions. Once this is done, the unit is fully functional and can now be used with the Sense App. Have fun!

Within the Sense App you can then view the current measurement data as well as the time history. If the sensor is placed e.g. in the bathroom, you will clearly see the temperature and humidity curves when someone showered or when the room was ventilated. If you want to be informed automatically about the exceeding or falling below of limit values (e.g. in case of danger of mould) you can do this with the help of the IFTTT integration.

To protect the components from dust and dirt, we recommend the installation in a plastic housing.