NodeMCU Sensor

A lot has changed since my last connected sensor project in 2013, so I wanted to jump in again to see how the technology has come along. After playing with some Particle Photon stuff, I came across NodeMCU. has lots of  ideas for this board, so I sought to recreate what Achraf Oukheir did there.

Achraf’s project is good, but it left out a lot of details, which I will summarize below. It was only by referencing Adafruit and Instructables for similar projects that I was able to eliminate errors and get the code to work. The other consideration is – if you have stepped away from Arduino for a while – just do yourself a favor and update your IDE first!

Tips and links:

Tip #1 – Update to latest Arduino IDE (unless told otherwise)
Tip #2 – Do not copy code into Notepad and back into Arduino IDE – it may introduce non-compliant quotes or other characters.
Tip #3 – Replace your DHT library with the latest one. The one I had was from 2013/14 and it did not work with this project. I used Adafruit’s library: Adafruit_Sensor
Tip #4 – Get the Blynk library directly from their site. Otherwise you might see an error like the one above.
Tip #5 – Be sure you have the NodeMCU. See this Instructables article.  Select NodeMCU 1.0 ( ESP-12EModule).
Tip #6 – See also Adafruit’s tutorials on this sort of thing. Different WiFi chip, but helpful for wiring.

So what did I think of this device? Things have come a LONG WAY since 2013! The app connectivity with Blynk is great. Less hardware, smaller footprint. The NodeMCU was $7 from – and now the newer version with Bluetooth and more capability is out for only a few more dollars. Crazy! The next step will be to possibly use this platform to create a notification setup for our hot tub for both temp and water level. Still considering Photon for that, but NodeMCU might be a good option too.

February 2018 Update

In order to free up my breadboard, I moved this project onto a Seeed breakout board that allowed me to make more solid connections. This design – housed in a take out container – survived harsh temps from February through April. I also added an email notification when temps got out of bounds. Hence the ice test.

The Seed board actually came with another NodeMCU board. It was dirt cheap, and appeared to be a poor copy and I had a lot of trouble with it. It was also a 1.0 vs the 0.9 version I had been using, so that created some confusion. A write-up is in the works, but frustration was high, so I had to step away.

May 2018 Update

The Seeed breakout was a bit overbuilt for this project, so to free up the Seeed I replaced it with the NodeMCU Carrier/Dev/Breakout Board, a purpose-built design by BK Hobby that I found on BK made his board files available, so I was able to include them in my order top PCBWay when my dad and I put an order together for some stuff we were designing.

To learn more about BK Hobby’s board:

BK Hobby’s Youtube Channel

Gerbers on PCBWay


3D models & Eagle CAD board and schematic files on Thingiverse


By jjdeprisco

Sonic explorer, sound artist, guitarist in Fricknadorable, software designer.