Continuous Monitoring of a USB Client for BCS Charging Capacity
First Claim
1. A method for continuously detecting when a USB client device may be charged according to a BCS standard comprising:
- applying power from a USB host device to the USB client device without exceeding a current limit;
initiating a procedure, the procedure comprising;
monitoring data lines D+ and D−
for a first part of a handshake from the USB client device wherein the first part of the handshake comprises;
applying no communication on the data lines from the USB client device and the USB host device during a time period T1; and
applying a first voltage on the D+ data line during the time period T1 by the USB client device;
providing a second part of the handshake from the USB host device when the first part of the handshake is detected;
completing the handshake;
providing current from the USB host device to the USB client device according to the BSC standard;
repeating the procedure.
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Accused Products
Abstract
An embodiment of the invention provides a method for continuously detecting when a USB client device may be charged according to a BCS charging standard. Power is supplied from a USB host device to the USB client device with a first current limit. Next, the USB host device monitors data lines D+ and D− for a first part of a handshake. When the first part of the handshake is detected, a second part of the handshake is provided by the USB host device indicating that the USB client device may be changed according to the BCS charging standard. All current sources and all voltage sources that are coupled to the data lines D+ and D− are decoupled from data lines D+ and D− after the handshake is complete. After the data lines are decoupled, communication may begin between the USB host device and the USB client device.
26 Citations
20 Claims
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1. A method for continuously detecting when a USB client device may be charged according to a BCS standard comprising:
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applying power from a USB host device to the USB client device without exceeding a current limit; initiating a procedure, the procedure comprising; monitoring data lines D+ and D−
for a first part of a handshake from the USB client device wherein the first part of the handshake comprises;applying no communication on the data lines from the USB client device and the USB host device during a time period T1; and applying a first voltage on the D+ data line during the time period T1 by the USB client device; providing a second part of the handshake from the USB host device when the first part of the handshake is detected; completing the handshake; providing current from the USB host device to the USB client device according to the BSC standard; repeating the procedure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for continuously detecting when a USB client device may be charged according to a BCS standard comprising:
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a handshake circuit having a first input connected to a D+ data line, a second input connected to a D−
data line, a first output connected to the D+ line, and a second output connected to the D−
data line;a USB host controller connected to the data line D+ and the data line D−
;wherein the handshake circuit detects when a first part of a handshake is applied to the data lines by the USB client device; wherein when the first part of the handshake is detected, the handshake circuit provides a second part of the handshake; wherein when the first part of the handshake is not detected, the outputs of the handshake circuit are decoupled from the data lines and enumeration begins; wherein when the second part of the handshake is completed, the outputs of the handshake circuit are decoupled from the data lines and enumeration begins. - View Dependent Claims (17, 18, 19, 20)
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Specification