Arduino does not connect to computer anymore Windows and Mac

I have the following problem since yesterday my Arduino Micro is not able to connect to the computer anymore. The blue light is working, but i can't choose a serial port and it is not recognized as a Hardware by my computer. I tried it on Windows (7) and MacOSX Sierra. So i thought it might be an issue with the connection, so i bought a new Arduino Micro today. I connected it with my Mac everything worked fine, then I opened the Serial Monitor and the connection was not available anymore. So with the new one it is the same problem now also on Windows and Mac. I hope someone can help me, because I have to do something important and I need them for that. I tried it with several Usb cables.

So I found a solution by myself, it is a bit weird and was more luck then knowledge. I have to double click the reset button, then i have connection for a few seconds, but enough to code the Arduino. But afterwards the connection is lost again, but at least i can successfully program it. Does anyone knows why this is like that and how to solve it ?

Hello JohannesKarl,

afaik the micro has the USB to Comm chip onboard of the ATmega32u4 (like the Leonardo). Other Arduinos come with special/separate serial communication chips (FTDI, CH340 ..).

The latter don't need the reset button to upload a sketch, but the Arduinos with the 32u4 chip need to be reset just before you upload a sketch. So in fact this is no problem but a feature :)

Additional information:

Automatic (Software) Reset and Bootloader Initiation Rather than requiring a physical press of the reset button before an upload, the Micro board is designed in a way that allows it to be reset by software running on a connected computer. The reset is triggered when the Micro's virtual (CDC) serial / COM port is opened at 1200 baud and then closed. When this happens, the processor will reset, breaking the USB connection to the computer (meaning that the virtual serial / COM port will disappear). After the processor resets, the bootloader starts, remaining active for about 8 seconds. The bootloader can also be initiated by pressing the reset button on the Micro. Note that when the board first powers up, it will jump straight to the user sketch, if present, rather than initiating the bootloader. Because of the way the Micro handles reset it's best to let the Arduino Software (IDE) try to initiate the reset before uploading, especially if you are in the habit of pressing the reset button before uploading on other boards. If the software can't reset the board, you can always start the bootloader by pressing the reset button on the board.

This information was found here.

Thank you for the information :)