The NodeMCU is the small but mighty brain powering the airrohr pollution sensor. It normally looks like this:
These little computers are really remarkable. For around £2 you can have a USB-powered, programmable computer capable of connecting to lots of sensors and other devices which can also connect to WiFi networks and even act as its own WiFi network. That’s a lot of bang for your buck.
Low price is not necessarily an indicator of low quality, but occasionally mistakes do slip through and a NodeMCU arrives which can’t be programmed up. In Windows this manifests itself as an error message which pops up when the device is connected, either:
USB DEVICE NOT RECOGNIZED
ONE OF THE USB DEVICES ATTACHED TO THIS COMPUTER HAS MALFUNCTIONED, AND WINDOWS DOES NOT RECOGNIZE IT. FOR ASSISTANCE IN SOLVING THIS PROBLEM, CLICK THIS MESSAGE.
THE LAST USB DEVICE YOU CONNECTED TO THIS COMPUTER MALFUNCTIONED, AND WINDOWS DOES NOT RECOGNIZE IT.
(Windows 8 and later)
This is the same message you see if the USB drivers for the NodeMCU haven’t been installed so it’s best to try that first. If you have already successfully installed the drivers and programmed other NodeMCUs the problem might lie with the device itself rather than with Windows.
If you take another look at the photo above you can see that the pins running along the top and bottom edges are quite close together and have fairly large solder blobs on them. It’s important that the blobs don’t touch each other as this has the same effect as wiring those two pins together. When this happens it is called a solder bridge and can be disastrous for your chip. Unfortunately solder bridges are fairly common on cheap NodeMCU boards so it’s worth checking your board over if it won’t connect in Windows.
Most guides to electronics on the web will advise you to remove some of the excess solder using a soldering iron and some solder wick to fix the problem, but this assumes you have the tools for the job which may not be the case. If there is only a small amount of solder joining the two pins together, a more rough-and-ready approach is possible:
- disconnect the NodeMCU
- find a sharp craft knife or stanley knife
- carefully slice a line across the solder bridge
- score the line back and forth a few times until you can clearly see a break between the solder blobs
- dust away any stray material
You can now give the NodeMCU another try on the PC. Good luck!
To find out more about common soldering faults take a look at Adafruit’s excellent visual guide to common soldering problems which can help you with a dozen common faults.