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 including a USB port having a first data line D+, a second data line D−, and a power line are disclosed. A USB device is attached to the USB port; applying power to the USB device by the power line; applying a first voltage to the line D+ at the USB port by a first impedance; applying a second voltage to the line D− at the USB port by 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 USB device connectable to a USB charging port, the USB charging port comprising a first data line D+, a second data line D−, and a power line, comprising:
means for attaching the USB device to a USB charging port; means for applying power to the USB device by way of the power line; means for applying a first voltage to the line D+ at the USB charging port; means for applying a second voltage to the line D− line at the USB charging port; and means for monitoring the current drawn on the power line; if the current drawn on the power line is below a first predetermined current value, then determining that the USB device is of a beta type; further comprising:
means for applying the first voltage to said line D− at the USB charging port;means for applying the second voltage to said line D+ at the USB charging port;means for monitoring the current drawn on the power line, wherein the USB device is of a gamma type if the current drawn on the power line increases above a second predetermined current value; andmeans for applying the first voltage to the line D+ and applying the second voltage to the line D− if the current does not increase above the predetermined value.