Identification/communication interface between consumer electronic devices and accessory devices

Patent metadata

Field	Value
Publication number	US-11934285-B2
Application number	US-202117151015-A
Country	US
Kind code	B2
Filing date	Jan 15, 2021
Priority date	Jan 15, 2021
Publication date	Mar 19, 2024
Grant date	Mar 19, 2024

Abstract

An accessory interface for an electronic host device includes a digital communication bus including a plurality of communication lines configured to pass data between the electronic host device and an electronic accessory device. The accessory interface further includes detection circuitry selectively coupled to the plurality of communication lines via a multiplexer and configured to detect analog voltage levels across the plurality of communication lines, determine a device type of the electronic accessory device based on the detected analog voltage levels, and control the multiplexer to couple the plurality of communication lines to a host processor of the electronic host device upon determining the device type of the electronic accessory device. The host processor is configured to receive the device type of the electronic accessory device and transmit data via the plurality of communication lines to the electronic accessory device in accordance with the device type of the electronic accessory device.

First claim

What is claimed is:

1. An accessory interface for an electronic host device, comprising:
a digital communication bus including a plurality of communication lines configured to pass data between the electronic host device and an electronic accessory device;
detection circuitry selectively coupled to the plurality of communication lines via a multiplexer, the detection circuitry configured to:
detect analog voltage levels across the plurality of communication lines;
determine first accessory identification (ID) information of the electronic accessory device based on the detected analog voltage levels, the first accessory ID information indicating that the electronic accessory is included in a group of accessory devices;
poll a memory of the accessory device to determine second accessory ID information of the electronic accessory device, the second accessory ID information indicating that the electronic accessory is included in a subset of the group of accessory devices;
determine a device type of the electronic accessory device based on the first accessory ID information and the second accessory ID information; and
control the multiplexer to couple the plurality of communication lines to a host processor of the electronic host device upon determining the device type of the electronic accessory device;

wherein the host processor is configured to:
receive the device type of the electronic accessory device from the detection circuitry; and
transmit data via the plurality of communication lines to the electronic accessory device in accordance with the device type of the electronic accessory device.

2. The accessory interface of claim 1 , wherein:
the detected analog voltage levels include (i) a first analog voltage level across a first of the plurality of communication lines and (ii) a second analog voltage level across a second of the plurality of communication lines; and
the detection circuitry is configured to determine the first accessory ID information of the electronic accessory device based on a mapping of the first analog voltage level and the second analog voltage level to the first accessory ID information in a lookup table stored in memory of the detection circuitry.

3. The accessory interface of claim 2 , wherein:
the first analog voltage level is set by a first resistor divider circuit including (i) a first pull-up resistor included in the electronic host device and (ii) a first pull-down resistor included in the electronic accessory device; and
the second analog voltage level is set by a second resistor divider circuit including (i) a second pull-up resistor included in the electronic host device and (ii) a second pull-down resistor included in the electronic accessory device.

4. The accessory interface of claim 3 , wherein:
the first and second pull-up resistors have fixed resistance values that are independent of the device type of the electronic accessory device; and
the first and second pull-down resistors have resistance values corresponding to the device type of the electronic accessory device.

5. The accessory interface of claim 3 , wherein:
the detection circuitry comprises an analog-to-digital converter (ADC) configured to detect the first and second analog voltage levels; and
the first and second pull-down resistors have resistance values that:
cause the first and second analog voltage levels to be greater than or equal to a minimum voltage threshold for digital communications over the plurality of communication lines, and
cause a difference between the first and second analog voltage levels to satisfy a minimum resolution requirement of the ADC.

6. The accessory interface of claim 1 , wherein:
the electronic host device is a camera; and the electronic accessory device is a camera stand, a solar panel, or a floodlight.

7. The accessory interface of claim 1 , wherein:
the digital communication bus is an inter-integrated circuit (I.sup.2C) bus;
a first of the plurality of communication lines is a serial clock line (SCL); and
a second of the plurality of communication lines is a serial data line (SDA).

8. The accessory interface of claim 1 , wherein the host processor is configured to transmit the data to the electronic accessory device in accordance with the device type of the electronic accessory device by transmitting a command that is specific to the device type of the electronic accessory device.

9. The accessory interface of claim 1 , wherein the host processor is further configured to wake from a low power state upon receiving the device type of the electronic accessory device from the detection circuitry.

10. The accessory interface of claim 1 , wherein upon disconnection of the electronic accessory device from the electronic host device, the host processor is further configured to (i) send a command to the detection circuitry to control the multiplexer to couple the plurality of communication lines to the detection circuitry, and (ii) transition to a low power state.

11. The accessory interface of claim 1 , wherein:
the first accessory ID information of the electronic accessory device comprises a general device category; and
the second accessory ID information of the electronic accessory device comprises a more-specific category, including the device type.

12. A method of interfacing an electronic host device with an electronic accessory device, the method comprising:
at detection circuitry selectively coupled, via a multiplexer, to a plurality of communication lines of a digital communication bus configured to pass data between the electronic host device and the electronic accessory device:
detecting analog voltage levels across the plurality of communication lines;
determining first accessory identification (ID) information of the electronic accessory device based on the detected analog voltage levels, the first accessory ID information indicating that the electronic accessory is included in a group of accessory devices;
polling a memory of the accessory device to determine second accessory ID information of the electronic accessory device, the second accessory ID information indicating that the electronic accessory is included in a subset of the group of accessory devices;
determining a device type of the electronic accessory device based on the first accessory ID information and the second accessory ID information; and
controlling the multiplexer to couple the plurality of communication lines to a host processor of the electronic host device upon determining the device type of the electronic accessory device; and

at the host processor:
receiving the device type of the electronic accessory device from the detection circuitry; and
transmitting data via the plurality of communication lines to the electronic accessory device in accordance with the device type of the electronic accessory device.

13. The method of claim 12 , wherein:
the detected analog voltage levels include (i) a first analog voltage level across a first of the plurality of communication lines and (ii) a second analog voltage level across a second of the plurality of communication lines; and
the detection circuitry determines the first accessory ID information of the electronic accessory device by matching the first analog voltage level and the second analog voltage level to the first accessory ID information in a lookup table stored in memory of the detection circuitry.

14. The method of claim 13 , wherein:
the first analog voltage level is set by a first resistor divider circuit including (i) a first pull-up resistor included in the electronic host device and (ii) a first pull-down resist

Assignees

• Google Llc

Inventors

• Zhang Haoxing
• Ho Dietrich Shing-Quan
• Lee Hung-Yang
• Saperstein William

Classifications

• G06F11/3051 Primary

  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) · CPC title

• G06F1/3287

  by switching off individual functional units in the computer system · CPC title

• G06F13/20

  for access to input/output bus · CPC title

• G06F13/4022

  using switching circuits, e.g. switching matrix, connection or expansion network (G06F13/4009 takes precedence) · CPC title

• G06F13/4068 Primary

  Electrical coupling · CPC title