Sunday, 22 July 2018





 NodeMCU ESP8266 Remote Temperature Using WebSockets

Story

The resulting modification leaves A0 on the breakout board directly connected to the ESP8266 input. When handling the NodeMCU board (or replicating this with just an ESP8266 module) you must practice proper anti-static handling procedures.
Modification to the NodeMCU to remove factory resistors

Part 2

Assembling the voltage divider network consisting of the 150K resistor and the 10K NTC thermistor. Please see the below schematic:The "rheostat" represents the thermistor
In determining the required value for the voltage divider, I utilized the Circuit Simulator online program. Using the Vishay NTC datasheet and noting the temperatures I wanted to display, I selected a potentiometer (and wired it as a rheostat) that had a value 50K Ohms which represents the value the thermistor would have at approximately -10C which is colder than I actually wish to monitor. The thermistor will have a value of approximately 500 Ohms at 100C which is the upper end of my desired measurement need (essentially from freezing to boiling.)
The next step is to connect the circuit on my solderless breadboard and do a test. I bought several thermistors, so I decided to sacrifice one by using 2-part epoxy and placing it inside a 1 foot stainless tube. I attached 1 meter of twisted flexible cable of 22 gauge (to maintain a very low series resistance and hence a negligible voltage drop.) I had already programmed the NodeMCU using Arduino IDE 1.6.9 and verified that the ESP8266 core file link was current using the board manager.
The Thermistor "probe" and the voltage divider test
I'm an engineer by training and a programmer by tough-luck, so there is always a hot cup of coffee around. I went upstairs and got a thermos of ice and water and back down to my makeshift lab for the hot to cold test (yes, using the coffee.)
ESP8266 under Arduino - SPIFFS and NodeMCU configuration:
To use the project, connect your PC to the Access Point created by the ESP8266. Now open an HTML5 compliant browser to 192.168.4.1

Schematics

Thermistor Voltage Divider Circuit

See text for LoLin NodeMCU modification
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Code

The Required files can be downloaded from here.

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