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Arduino Will Not Show up on Serial Port--How to Install Arduino USB Drivers in Windows 7 on a PC or on VirtualBox · Share Your Repair
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COM port number changes when connecting board on different ports or in bootloader mode – Arduino Help Center
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COM port number changes when connecting board on different ports or in bootloader mode – Arduino Help Center
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No output in Serial Monitor for example program: ds3231 date and time functions - Programming Questions - Arduino Forum
![COM port number changes when connecting board on different ports or in bootloader mode – Arduino Help Center COM port number changes when connecting board on different ports or in bootloader mode – Arduino Help Center](https://support.arduino.cc/hc/article_attachments/360016532000/COM_port_changes_2.png)