I have just purchased a Wemos D1 Mini to use with a small display to link to Octoprint on my 3D printer as a Print monitor. I am following an Instructable on how to connect everything up and to know which Libraries I need, as well as the code for the display.
As I have never used an Arduino board before, I did some research and came across an Instructable which would put some Example code on my board. This was to help with learning Arduino IDE and to make sure the board was ok.
I chose the “Blink” Example and following the Instructable I now have a blinking LED on my board 
However, that was yesterday and it is still blinking. Even if I unplug it from power and plug it back in, it keeps on blinking.
So my question is: How do I stop it? Or will it only stop when I overwrite it with the code for the Octoprint monitor?
Many thanks in advance from an absolute beginner!
kevinpaul28:
Even if I unplug it from power and plug it back in, it keeps on blinking.
This is normal and expected. When you upload a sketch to an Arduino board, it is written to the microcontroller's non-volatile flash memory and will stay there even after the board is disconnected from the power supply or the computer. After that, all the microcontroller needs is a power source and it will run the sketch, even if it's not connected to the computer.
kevinpaul28:
So my question is: How do I stop it?
When you upload a sketch to the Arduino board, it overwrites the previous sketch in the flash memory. So you can simply upload another sketch. If you want the LED to stop blinking, an easy thing to do is to just do a File > New in the Arduino to get a bare minimum sketch (which doesn't really do anything), then upload that sketch to the board.
kevinpaul28:
Or will it only stop when I overwrite it with the code for the Octoprint monitor?
That will do it.
kevinpaul28:
Many thanks in advance from an absolute beginner!
Welcome to the wonderful world of embedded systems!
Thank you for prompt and helpful reply. I’ll try a “New” upload to get the hang of the interface.
My next struggle will be working my way through the Instructable and uploading Libraries.
I got my first computer back in 1980 and soldered all the components together, I was in my twenties then and my brain was a bit better at learning new things !!
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