# US 12,216,602 B2 · Methods and apparatus to detect L2 entry and reset in universal serial bus repeaters > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,216,602 B2 - Document ID: US12216602B2 - Status: Granted - Kind: B2 - Application number: 17/581,202 - Filed: 2022-01-21 - Published: 2023-07-27 - Granted: 2025-02-04 - Earliest claimed: 2022-01-21 - Assignees: Texas Instruments Incorporated - Applicants: Texas Instruments Incorporated - Inventors: Anant Kamath; Suzanne M. Vining; Rakesh Hariharan; Mark Wentroble; Christopher Rodrigues; Prajwala P - Web page: https://patentgrep.com/patent/US12216602B2 ## CPC - G06F 13/385: {for adaptation of a particular data processing system to different peripheral devices} - G06F 13/4027: {using bus bridges (G06F13/4022 takes precedence)} - G06F 13/4068: {Electrical coupling} - G06F 13/4295: {using an embedded synchronisation} - G06F 2213/0042: Universal serial bus [USB] - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract An example apparatus includes: a pullup circuit coupled to a first USB terminal; a first pulldown circuit coupled to the first USB terminal; a second pulldown circuit coupled to a second USB terminal; a third pulldown circuit coupled to a third USB terminal; a fourth pulldown circuit coupled to a fourth USB terminal; a high-speed termination detection circuit including: a current source including a first supply terminal and a second supply terminal, the first supply terminal coupled to the first USB terminal, the second supply terminal coupled to the second USB terminal; a first comparator including a first comparator terminal and a second comparator terminal, the first comparator terminal coupled to the first USB terminal; and a second comparator including a third comparator terminal and a fourth comparator terminal, the third comparator terminal coupled to the second USB terminal; and a controller including a first control terminal and a second control terminal, the first control terminal coupled to the second comparator terminal, the second control terminal coupled to the fourth comparator terminal. ## Claims ### Claim 1 A system comprising a USB repeater, the USB repeater including: an upstream circuit; a downstream circuit; a controller coupled to the upstream circuit and the downstream circuit; and wherein the USB repeater is configured to: replicate a transmission to the upstream circuit on the downstream circuit; determine whether a duration without USB communications between the upstream circuit and the downstream circuit is greater than a threshold; in response to determining the whether the duration without USB communication is greater than the threshold, the controller enables a high-speed termination detection circuit; in response to the high-speed termination detection circuit being enabled, the high-speed termination detection circuit compares an output of the upstream circuit to a reference; in response to comparing the output of the upstream circuit to the reference, the high-speed termination detection circuit determines whether a state of a device coupled to the upstream circuit is a reset state or a suspend state; and in response to determining the state of the device, the controller sets the downstream circuit to replicate the state of the device. ### Claim 2 (depends on 1) The system of claim 1, wherein the USB repeater is configured to replicate USB communication between a primary device coupled to the upstream circuit and a secondary device coupled to the downstream circuit. ### Claim 3 (depends on 1) The system of claim 1, wherein the high-speed termination detection circuit determines the state of the device by enabling circuitry to determine whether or not a resistor is configured to pulldown the output of the upstream circuit. ### Claim 4 (depends on 1) The system of claim 1, wherein the controller is configured to replicate the state of the device by controlling a pulldown circuit coupled to an output of the downstream circuit, wherein disabling the pulldown circuit is to replicate the suspend state. ### Claim 5 (depends on 1) The system of claim 1, wherein the USB repeater includes a logic isolation circuit, the logic isolation circuit is coupled between the upstream circuit and the downstream circuit. ### Claim 6 (depends on 5) The system of claim 5, wherein the logic isolation circuit is configured to supply the downstream circuit a transmission from the upstream circuit. ### Claim 7 A method of communicating between a primary USB device and a secondary USB device, the method comprising: controlling a USB repeater circuit, situated between the primary USB device and the secondary USB device, to replicate a USB communication between the primary USB device and the secondary USB device, the USB repeater circuit having a first terminal and a second terminal coupled to the primary USB device; providing current from one or more current source in a high-speed termination detection circuit to each of the first terminal and the second terminal; comparing current provided to the first terminal with a reference current to generate a first indication; comparing current provided to the second terminal with the reference current to generate a second indication; determining a state of the primary USB device is in a suspend state or a reset state based on the first indication and the second indication; controlling the USB repeater circuit to replicate a state of the primary USB device; and controlling the USB repeater circuit to replicate a state of the secondary USB device. ### Claim 8 (depends on 7) The method of claim 7, wherein the high-speed termination detection circuit determines whether or not a pulldown circuit is enabled by the primary USB device to indicate high-speed USB communication. ### Claim 9 (depends on 7) The method of claim 7, wherein the USB repeater circuit includes a pulldown circuit, which may be controlled to replicate the USB communication in high-speed mode based on the high-speed termination detection circuit. ### Claim 10 (depends on 7) The method of claim 7, wherein a pullup circuit of the second USB device is controlled based on the high-speed termination detection circuit, wherein the pullup circuit is enabled to replicate the USB communication in full speed mode.