ESP8266 NodeMcu ESP8266 Module (4pcs),ESP-12E NodeMcu LUA CP2102 Internet WiFi Development Board Works with Arduino IDE/Micropython

First of all, only 3 of the 4 worked as received. One seemed to be DOA and, of course, it was the first one I tried. I spent maybe an hour trying to figure out if it was an issue with the Arduino IDE setup before I just tried another board. It turns out the one I thought was DOA had a bit of solder shorting the TX pin to GND. After cutting that solder bridge the board worked as well as any of the others, as far as I could tell. Not that they worked for my current project, as explained below.I bought these because I was hoping the faster 80MHz processor would be more reliable in ensuring I did not miss edges from some encoders I was using in my project. I didn't need the wifi features, but thought I might be able to make use of it down the road. It turns out the code I want to use doesn't play well with the watchdog timers in these modules. I need the code to wait for user input before proceeding to other tasks. Unfortunately, this seems to result in the chip constantly resetting every 1.8 seconds or so. I have tried using the yield() and ESP.wdtFeed() recommendations that seem to fix many of the reset issues others have had but so far I have not been able to get anything to work. I still need to try the recommended capacitors on the power supply side, but everything seems to work fine with other example sketches included with the Arduino IDE, so I think the issue is with my code and the way I want it to function, not the power supply. Oh well, they were cheap enough and I may find a use for them down the road.

I bought a handful of ESP8266 and ESP32s from different vendors, to test several varieties. I had seen that nearly every seller and product had the occasional dead-on-arrival item review, but I had no DOAs from any order. I prepared for this product by reviewing documentation and reading others' questions/answers, and by reading example programs others wrote.My NodeMCU ESP8266s from ETMall all successfully ran basic blink programs successfully after flashing them and uploading the program from the Arduino IDE. It took about a minutes for each to verify they were working. I already had the Arduino IDE set up with the ESP8266 libraries from a previous board, so I didn't have that concern.(At this price, I'd still go 4 stars even if one had been DOA and the rest worked just fine.)I'll update this review if anything changes.

About the seller: These are some the most stable and honestly the cleanest looking NodeMCU's that me and my team have managed to find on the internet. 4 for $20 is a great deal and a good idea to get more than 2 at a time just for cost effectiveness, because they are so useful, and because it is really really easy to break these guys.About the microcontroller: NodeMCU's are becoming a popular development board because they have a wifi module built in and are super cheap. However, you get what you pay for. These devices are very sensitive to voltage spikes and do not have the protections that an Arduino or RaspberryPi would have. So use with caution. As an electrical engineer, these have been useful for teaching what can go wrong when you work with a real-world controller versus the best-case scenario.

I already had an ESP8266 to try out, so these were plug and play for me. They work great. If you are coming from Arduinos, these only have about 5 usable pins without restrictions and they are a bit more complex, but also much faster and WiFi/web access means more functionality.

One of the boards had a damaged silkscreen (see picture). All boards function correctly and are individually wrapped in anti-static packaging with foam on pins.

I tried all four of these boards, and not a single one worked. None of them read the com port. I tried to get the firmware installer, but it is hard to flash a board you can't access.Update: ended up getting a few of them working after a lot of tinkering and a lot of forum searching. They work well if you can get everything to talk to everything else.

Ordered a set of these, 1 of the 4 was bad (no USB com). Seller was very quick to resolve the issue. Ordered another set of 4 and all of those worked out of the bag. I've had 4 of them running multiplexers pulling sensor data from 8 capacitive sensors each for the last 24 hours. Might just be the best deal to be had on esp-12e's on Amazon. Give them a shot.

Good price, great product except one of the four modules did not work. No matter how hard I tried it would not take a flash. I bought several sets of these since, and all have worked fine just the one was bad.

Two of the four arrived with severely bent pins. I was able to straighten out the pins to get it to fit in a breadboard, but the first one I tested was defective and wouldn't work at all. The second one worked fine once the pins had been straightened.

Box ok, Nice pack but bent pins

Delivered on time, packed nicely, all working as expected. Can’t fault this order at all.