Arduino Leonardo(Atmega32u4) - Detecting if USB is connected to a computer?

Question

The closest thing I can find is if(Serial) but that only returns true if there's a serial port open.

The function I want, ideally, should:

Return true if plugged into a computer

Return false if plugged into a USB power bank

Return false if not plugged in at all(Running off of its own lithium cell)

Ignacio Vazquez-Abrams · Accepted Answer · 2017-07-24 17:18:54Z

5

ADDEN of UDADDR is set if the '32U4 has been assigned a USB address by the host and the firmware wants to enable USB connectivity.

UDADDR & _BV(ADDEN)

answered Jul 24, 2017 at 17:18

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Is there something similar for VBUS detection to get the (not)plugged in?
– Majenko
Commented Jul 24, 2017 at 17:36
@Majenko: VBUS in USBSTA.
– Ignacio Vazquez-Abrams
Commented Jul 24, 2017 at 17:37
Stupid question, but where do I go from here? Is it as easy as (UDADDR & _BV(ADDEN)) != B00000000 ?
– Stephen
Commented Jul 24, 2017 at 18:48
1

if (UDADDR & _BV(ADDEN)) ...
– Ignacio Vazquez-Abrams
Commented Jul 24, 2017 at 22:13
Works but there is a problem with battery powered equipment when you disconnect the USB cable. This still returns true and after an restart it returns false. How to fix this?
– Codebeat
Commented Oct 12, 2017 at 23:39

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