INTERFACE DETECTION CIRCUIT

摘要

One or more characteristics of devices are ascertained in accordance with one or more aspects of the disclosure. As may be consistent with one or more embodiments, the attachment of an external circuit to an input port is detected based on a resistance value presented by the external circuit. A resistance range that includes the resistance value presented at the input port is determined, in response to detecting the attachment, by dynamically coupling one or more of a plurality of resistor-based circuits relative to the input port. A signal presented by the external circuit on the input port is coded based on the determined resistance range, using one or more of the resistor-based circuits, and the code is used to identify a type of the external circuit. These aspects can provide for the communication of power and data with a variety of different types of external circuits.

主权项

1. An apparatus comprising:
an input port configured and arranged to communicate power and data with a plurality of different types of external circuits that respectively provide a resistance value at the input port that is different than resistance values presented at the input port by each other one of the plurality of different types of external circuits; a first circuit configured and arranged to
in a first mode, detect attachment of an external circuit to the input port based on a resistance value presented by the external circuit on the input port; andin response to detecting the attachment of the external circuit, switch from the first mode to a second mode, and while in the second mode, determine a resistance range that includes the resistance value presented at the input port by dynamically coupling one or more of a plurality of resistor-based circuits relative to the input port; and a second circuit configured and arranged with the first circuit to, based on the determined resistance range and using the one or more of the plurality of resistor-based circuits, code a signal presented by the detected external circuit on the input port and identifying the type of the external circuit based on the coding.