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)

score 5 · Accepted Answer · answered Jul 24 '17 at 17:18

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 '17 at 17:18

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

if (UDADDR & _BV(ADDEN)) ... – Ignacio Vazquez-Abrams Jul 24 '17 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 Oct 12 '17 at 23:39
Rewrite the firmware to deconfigure USB when disconnected. – Ignacio Vazquez-Abrams Oct 13 '17 at 00:08
This willl wait for serial monitor to be opened if usb connected before proceeding: if (UDADDR & _BV(ADDEN)){ while (!Serial);} – Hayden Thring Dec 16 '19 at 01:07

1 Answers1