Handheld USB Device Accessory Mode Host Discovery
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Solution Overview
Problem
The USB standard does not provide a convenient mechanism for handheld devices with limited power supplies to function as USB hosts, limiting their ability to discover and interact with USB-compatible hosts, especially when they lack necessary software to interoperate with accessories.
Innovation Solution
A method and system that allow a handheld computing device to operate in accessory mode, enabling it to receive host configuration information from a USB host, thereby identifying the host and acquiring necessary software to interoperate with USB hosts, even if the device cannot provide power or function as a traditional USB host.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If handheld devices function as USB devices (slaves) rather than hosts, then they can connect to USB hosts and receive power, but they cannot discover or interact with USB hosts without pre-installed software
Solution Approach 1:
The patent inverts the traditional USB host-device relationship by enabling a handheld device to receive host configuration information from a USB host, allowing the device to identify and adapt to the host system. This reversal allows the slave device to gain host-like discovery capabilities without becoming a full USB host.
2Adaptability or versatility
If handheld devices attempt to function as USB hosts, then they can discover USB accessories, but they lack sufficient power supply to support host operations
Solution Approach 1:
The patent extracts the essential host functionality (discovery and identification capabilities) from the complete USB host role, allowing handheld devices to perform selective host functions without承担ing the full power burden of being a complete USB host. The device receives configuration information rather than actively managing the entire host protocol stack.
3Adaptability or versatility
If handheld devices lack pre-installed software for USB host interoperability, then power consumption is reduced, but they cannot interact with USB hosts
Solution Approach 1:
The USB host performs preliminary configuration actions by providing configuration information to the handheld device during the connection establishment phase. This preliminary action eliminates the need for pre-installed software on the handheld device, as the host prepares and transmits the necessary configuration data in advance.
Data Source
AI summary
A system and method for serial communication between a USB host and a USB device. The USB device is a handheld microprocessor equipped device capable of functioning as a general purpose computer. The USB host places the USB device in an accessory mode which permits the USB host to transmit its configuration information to the USB device. This configuration information can include the manufacturer and product ID of the USB host. The USB device, in accessory mode, uses this configuration information to acquire and load application software (such as by downloading the software from the Internet). The application software enables the USB device to provide a programmable function to the USB host and to enable applications on the USB host and device to communicate on a peer-to-peer basis via the USB communications channel.