Methods and apparatus to detect L2 entry and reset in universal serial bus repeaters

Patent metadata

Field	Value
Publication number	US-12216602-B2
Application number	US-202217581202-A
Country	US
Kind code	B2
Filing date	Jan 21, 2022
Priority date	Jan 21, 2022
Publication date	Feb 4, 2025
Grant date	Feb 4, 2025

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.

First claim

What is claimed is:

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.

2. 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.

3. 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.

4. 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.

5. 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.

6. The system of claim 5 , wherein the logic isolation circuit is configured to supply the downstream circuit a transmission from the upstream circuit.

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.

8. 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.

9. 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.

10. 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.

Assignees

• Texas Instruments Inc

Inventors

• Kamath Anant
• Vining Suzanne M
• Hariharan Rakesh
• Wentroble Mark
• Rodrigues Christopher
• P Prajwala

Classifications

• G06F13/4068

  Electrical coupling · CPC title

• G06F2213/0042

  Universal serial bus [USB] · CPC title

• G06F13/4027

  using bus bridges (G06F13/4022 takes precedence) · CPC title

• G06F13/4295

  using an embedded synchronisation · CPC title

• G06F13/385 Primary

  for adaptation of a particular data processing system to different peripheral devices · CPC title