# US 2014/0156876 A1 · Device disconnect detection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0156876 A1 - Document ID: US20140156876A1 - Status: Published application - Kind: A1 - Application number: 14/176,653 - Filed: 2014-02-10 - Published: 2014-06-05 - Earliest claimed: 2012-06-30 - Assignees: Intel Corporation - Inventors: Kok Hong Chan; Huimin Chen - Web page: https://patentgrep.com/patent/US20140156876A1 ## CPC - G06F 13/385: {for adaptation of a particular data processing system to different peripheral devices} - G06F 1/266: {Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips} - G06F 1/3209: Monitoring remote activity, e.g. over telephone lines or network connections - G06F 1/3215: Monitoring of peripheral devices - G06F 1/3253: {Power saving in bus} - G06F 11/3041: {where the computing system component is an input/output interface (interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units G06F13/00)} - G06F 11/3051: {Monitoring arrangements for monitoring the configuration of the computing system or of the computing system component, e.g. monitoring the presence of processing resources, peripherals, I/O links, software programs (verification or detection of system hardware configuration G06F11/2247)} - G06F 11/3055: {Monitoring arrangements for monitoring the status of the computing system or of the computing system component, e.g. monitoring if the computing system is on, off, available, not available (error or fault processing without redundancy G06F11/0703; error detection or correction by redundancy in data representation G06F11/08; error detection or correction of the data by redundancy in operations G06F11/14; error detection or correction by redundancy in hardware G06F11/16)} - G06F 13/4282: {on a serial bus, e.g. I2C bus, SPI bus (on daisy chain buses G06F13/4247)} - G06F 2213/0042: Universal serial bus [USB] - Y02D 10/00: Energy efficient computing, e.g. low power processors, power management or thermal management - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract Systems and methods for operating a universal serial bus are described herein. The method includes sending packet data from a USB2 device to a USB2 host on a pair of signal lines, and after sending the packet data, sending an End-Of-Packet (EOP) signal from the USB2 device to the USB2 host. The method also includes, entering the USB2 device into idle state after sending the EOP signal. The method also includes sending a digital ping from the USB2 device to the USB2 host to indicate device presence during idle state. ## Claims ### Claim 1 A method of operating a universal serial bus, comprising: sending packet data from a Universal Serial Bus (USB) host to a USB device on a pair of signal lines, and after sending the packet data, sending an End-Of-Packet (EOP) signal from the USB host to the USB device; after sending the EOP signal, entering the USB device into idle state; and during idle state, sending a digital ping from the USB device to the USB host to indicate device presence. ### Claim 2 (depends on 1) The method of claim 1, comprising the USB device periodically sending additional digital pings over a specified time interval to indicate continued device presence. ### Claim 3 (depends on 1) The method of claim 1, comprising the USB host declaring device disconnect if the USB host does not receive the digital ping from the USB device within a specified time period. ### Claim 4 (depends on 1) The method of claim 1, comprising the USB host declaring device disconnect if the USB host does not receive the digital ping for three consecutive frames. ### Claim 5 (depends on 1) The method of claim 1, comprising the USB device indicating device presence without using passive pull up resistors. ### Claim 6 (depends on 1) The method of claim 1, the EOP signal is sent form the USB host to the USB device on a first signal line of the pair of signal lines, and the digital ping is sent from the USB device to the USB host on a second signal line of the pair of signal lines. ### Claim 7 (depends on 1) The method of claim 1, comprising the USB host holding both signal lines of the pair of signal lines to ground during idle state. ### Claim 8 A Universal Serial Bus (USB) host comprising: a host port comprising a physical layer to send and receive data on a pair of signal lines to a device, the host port to: send an End-Of-Packet (EOP) signal to the device following the transmission of packet data, wherein the EOP signal causes a port of the device to enter idle state; and receive a digital ping from the device to determine the presence of the device. ### Claim 9 (depends on 8) The USB host of claim 8, wherein the host port periodically receives additional digital pings over a specified time interval that indicates continued device presence. ### Claim 10 (depends on 8) The USB host of claim 8, wherein the USB host is to declare device disconnect if the host port does not receive the digital ping from the device within a specified time period. ### Claim 11 (depends on 8) The USB host of claim 8, wherein the USB host is to declare device disconnect if the host port does not receive the digital ping for three consecutive frames. ### Claim 12 (depends on 8) The USB host of claim 8, wherein the host port sends the EOP signal on a first signal line of the pair of signal lines, and the digital ping is received from the device on a second signal line of the pair of signal lines. ### Claim 13 (depends on 8) The USB host of claim 8, wherein the host port holds both signal lines of the pair of signal lines to ground during idle state. ### Claim 14 A Universal Serial Bus (USB) device, comprising: a device port comprising a physical layer to drive signals on a first signal line and a second signal line for communicating with a USB host; wherein, upon entering an idle state, the device port sends a digital ping to the USB host on one of the pair of signal lines to indicate device presence. ### Claim 15 (depends on 14) The USB device of claim 14, wherein the device port indicates device presence without using passive pull up resistors. ### Claim 16 (depends on 14) The USB device of claim 14, wherein the device port periodically sends additional digital pings over a specified time interval to indicate continued device presence. ### Claim 17 (depends on 14) The USB device of claim 14, wherein the time separation between the additional digital pings is less than three frames. ### Claim 18 (depends on 14) The USB device of claim 14, wherein the device port enters the idle state upon receiving an EOP signal from the USB host on a first signal line of the pair of signal lines, and the digital ping is sent to the USB host on a second signal line of the pair of signal lines. ### Claim 19 (depends on 14) The USB device of claim 14, wherein, the USB device is a chip disposed in a same motherboard as the USB host. ### Claim 20 (depends on 19) The USB device of claim 19, wherein, during a Sleep (L1) or Suspend state, the USB device powers down a transmitter of the device port and does not send digital pings to the USB host while still maintaining device presence.