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Topic: How To Tell If USB Is Connected.... (Read 149 times) previous topic - next topic


Is there any way to determine, on either the Programming Port or Native Port, if there is an active USB connection, WITHOUT sending or receiving data.  In particular, I'd like to be able to detect if either port is connected to a PC, and the PC COM device opened.  Perhaps there is some way of detecting a toggle on one of the (virtual) handshake lines, like CTS?

Ray L.


If you mean tell in the Arduino board, perhaps someone in AVRfreaks forum could tell.


Don't know if this would work, but could you try connecting one of the USB data pins to a digital input?


USB data voltages are differential and around about 1-2V. Using digital input like that probably would not work



There is a pull up resistor in one dataline. That tells the host there is something connected.

Read the datasheet of the chip which handles the USB bus. I think in DUE it is the CPU ATSAM3X. So, read the USB part of the datasheet and ask about this AVRfreaks forum.


The equality operator is overloaded for SerialUSB so you can just see if it is true. If it's true then there is something connected to the USB board. If it is false then there isn't.

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