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Topic: What Causes "Serial port 'COM#" already in use" (Read 2 times) previous topic - next topic

nobikes

Hello,

I have been building line following bots with my engineering 9-12 class for a few years. We are using a motor shield I developed. Previously 1 in 10 of the student made boards would have the "Serial port COM# already in use" issue and I put it off as student error.  The current semester class is having the "Serial port COM# already in use" with almost every board and for the life of me I cannot figure it out.

The issue is as soon as you plug in the board to the uno the error comes up when you try to upload a new sketch. The uno will run the any previous sketches uploaded to it but it will not allow a new sketch to be uploaded. I know I can get around this by unplugging the boards uploading the sketch and putting them back together but that makes trouble shooting 30 student projects very time consuming.

My question is what could be feeding back to the arduino to cause the "Serial port COM# already in use" problem? And what could I do to stop it from happening?

Thank you,


High School Engineering Teacher

kf2qd

Are the computers shut down between sessions? I find this happens when I shut down one Arduino Window when the Serial Monitor is open. Also sometimes turns up when I have reconnected the Arduino several times in close succession. I think the problem is in the Java side of things, that some internal variable gets stuck.

nobikes

The problem occurs only with the motor shield on. when it is off and the Arduino is unpluged and pluged back in every thing is back to normal, untill the motor shield goes back on. I think it has to be some sort of feed back issue.
High School Engineering Teacher

Coding Badly


nobikes

High School Engineering Teacher

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