There is a real dearth of information on flashing the esp8266 nodemcu dev boards.
You will find 3 different conflicting methods online.
This information is strictly for the esp8266 nodemcu version 1.0 pictured below.
What is AT firmware?
When you first get the board, it will be flashed with nodemcu firmware. More interestingly it has AT firmware on it.
What is AT? Basically it allows you to connect your board to your PC and using com ports, send commands directly to the esp8266 using simple commands.
The list of things you can do are listed here.
Basically its a great way of testing that the board you got is in working order before trying anything else with it.
Below I connected the board to the PC via usb cable and using the Arduino serial monitor, I was able to send the “AT” test command to get back “OK” indicating the board is working.
One thing to take note is, if you decide to program the board using the Arduino IDE, nodemcu lua or the actual esp8266 sdk, it will wipe whatever is stored on the chip.
In my case, I uploaded a test blink LED sketch to the nodemcu board and after that I lost the ability to issue AT commands.
The fix is simple from there, just re flash with the original firmware.
How To Flash
- Download the required files from https://github.com/Stadslab/ESP8266_example
You want to download all the files in the folder pictured below.
- Run the flasher app.
Select the bin file, and set the COM port to the correct number. (For me it was Com3)
Leave all other settings as is.
- This is important, you need to put the board into FLASH mode or else you will get the following error.
It will say “Failed to connect” in the log window.
- To place the nodemcu into FLASH mode is super easy.
- If you do it right the flash operation will commence.