Methods, systems and apparatus for determining whether an accessory includes particular circuitry
First Claim
1. A method of determining whether an accessory includes particular circuitry, comprising:
- measuring, at a host device coupled to an accessory, a first voltage received from the accessory, the first voltage being received via a power pin provided in the host device;
sending, by the host device, an instruction to the accessory to alter an impedance, at the accessory, of a power path between a power source and the host device;
measuring, at the host device, a second voltage received from the accessory, the second voltage being received via the power pin provided in the host device; and
determining, by the host device, whether the accessory includes particular circuitry based on the relationship between the first voltage and the second voltage.
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Abstract
Methods, systems, and apparatus for determining whether an accessory includes particular circuitry. A host device may measure a first voltage and a second voltage received from an accessory, where the voltages are provide through the accessory from a power source. Before measuring the second voltage, the host device may send an instruction to the accessory instructing the accessory to alter an impedance of the power path between the power source and the host device, and the host device may draw at least a threshold amount of current from the power source via the accessory. The host device may then determine whether the accessory includes particular circuitry based on the relationship between the first voltage and the second voltage.
58 Citations
20 Claims
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1. A method of determining whether an accessory includes particular circuitry, comprising:
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measuring, at a host device coupled to an accessory, a first voltage received from the accessory, the first voltage being received via a power pin provided in the host device; sending, by the host device, an instruction to the accessory to alter an impedance, at the accessory, of a power path between a power source and the host device; measuring, at the host device, a second voltage received from the accessory, the second voltage being received via the power pin provided in the host device; and determining, by the host device, whether the accessory includes particular circuitry based on the relationship between the first voltage and the second voltage. - View Dependent Claims (2, 3, 4)
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5. A method of determining whether an accessory includes particular circuitry, comprising:
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measuring, at a host device coupled to an accessory, a first voltage received from the accessory, the first voltage being received via a power pin provided in the host device; sinking, at the host device, current from a power source via the accessory; measuring, at the host device, a second voltage received from the accessory, the second voltage being received via the power pin provided in the host device; and determining, by the host device, whether the accessory includes particular circuitry based on the relationship between the first voltage and the second voltage. - View Dependent Claims (6, 7, 8, 9)
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10. A host device comprising:
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a power pin operable to receive a voltage from an accessory; a data pin operable to communicate an instruction to the accessory; and control circuitry operable to; measure a first voltage received from the accessory via the power pin; send an instruction to the accessory via the data pin, the instruction instructing the accessory to alter an impedance, at the accessory, of a power path between a power source and the host device; sink current from the power source via the accessory; measure a second voltage received from the accessory via the power pin; and determine whether the accessory includes particular circuitry based on the relationship between the first voltage and the second voltage. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification