Pro Micro changing ports during upload of sketch

Development Boards Arduino
1

Hi Guys,

I know there is a lot of information about this on all the forums but I don’t seem to find a solution to my problem.

My setup

1.Windows 10

2.Arduino 1.8.12

3.All the sparkfun boards installed.

Problem: Connecting the pro Micro with the usb, it will change ports during the download of a new sketch resulting in the download not being successful.

What I have done:

  1. Followed the 2 button reset process. 8 seconds is not enough to load a sketch and it is not consistently working. The way I develop is to test constantly during coding. If I have have to do this every time a push something to the board it would kill me.

  2. Reloaded the the bootloader using a Uno as ISP. Results are the first time I connect it, it loads the new sketch with no problem. Second time I try to load the sketch I get the dreaded port switching issue again.

Solution I have found:

Program the pro Micro using the Uno as programmer. This works perfectly but obviously the bootloader software is missing then. So you have to keep doing this and it can become a problem ones the micro is build into a full project.

I am positive there is a patch out there that will fix this issue.

Please assist as I am lost now.

Thanks

2

What you’re seeing is actually normal.

The bootloader in the board has it’s own serial port and when you upload code, that triggers the bootloader. The Arduino IDE is supposed to know about the change and will search for the bootloader COM port when it activates.

What might be happening in your case is your computer might be a bit slow and be taking longer than 8 seconds to find the new port and after 8 seconds the bootloader ends and the board reappears on it’s old COM port. You might try a different computer and see if you can upload there.