Devices and methods for detecting USB devices attached to a USB charging port

摘要

Methods and devices for detecting USB devices attached to a USB charging port are disclosed. The USB charging port includes a USB port having a first data line D+, a second data line D−, and a power line. A method includes attaching the USB device to the USB port; applying power to the USB device by way of the power line; applying a first voltage to the line D+ at the USB port by way of a first impedance; applying a second voltage to the line D− at the USB port by way of a second impedance. The voltages on the line D+ and the line D− are then monitored at the USB port. If the voltage on the line D+ is approximately equal to a first predetermined value for a predetermined period and the voltage on the line D− is below a second predetermined value, then the USB device is determined to be of an alpha type device.

主权项

1. A method for detecting the type of USB device attached to a USB charging port, said USB charging port comprises a USB port comprising a first data line D+, a second data line D−, and a power line, said method comprising:
attaching said USB device to said USB port; applying power to said USB device by way of said power line; applying a first voltage to the line D+ at said USB port by way of a first impedance; applying a second voltage to the line D− at said USB port by way of a second impedance; and monitoring the voltages on said line D+ and said line D− at said USB port; if said voltage on said line D+ is approximately equal to a first predetermined value for a predetermined period and said voltage on said line D− is below a second predetermined value, then said USB device is determined to be of an alpha type device.