Resistor/Capacitor Based Identification Detection
First Claim
1. A system for providing host system identification, the system comprising:
- a pin configured to couple to a first circuit having a time constant;
a second circuit configured to compare a first voltage value with a pin voltage developed at the pin, and to generate a first signal indicative of whether the pin voltage has reached the first voltage value; and
a third circuit operable to store a numeric value corresponding to the time constant, responsive to the first signal indicating that the pin voltage has reached the first voltage value;
wherein the numeric value corresponds to identification information of a host system comprising the system.
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Accused Products
Abstract
A resistor/capacitor identification detection (RCID) circuit may provide system level identification of hardware (e.g. circuit board ID) through a single pin interface, by identifying up to a specified number of more than two quantized RC time constant states by measuring the discharge and charge times of an external RC circuit coupled to the single pin. The RCID circuit may initiate the discharge followed by a charging of the external RC circuit. The signal developed at the signal pin may be provided to the input of a threshold detector, with the threshold set at a specified percentage of a supply voltage used for operating the RCID circuit. The digitized output of the threshold detector may be used to gate a counter, after having been filtered through an input glitch rejection filter. A resolution of the counter may be determined by a high frequency clock used for clocking the counter. The numeric values of the charge and discharge times may be stored in data registers comprised in the RCID circuit.
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Citations
27 Claims
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1. A system for providing host system identification, the system comprising:
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a pin configured to couple to a first circuit having a time constant; a second circuit configured to compare a first voltage value with a pin voltage developed at the pin, and to generate a first signal indicative of whether the pin voltage has reached the first voltage value; and a third circuit operable to store a numeric value corresponding to the time constant, responsive to the first signal indicating that the pin voltage has reached the first voltage value; wherein the numeric value corresponds to identification information of a host system comprising the system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for providing host system identification, the method comprising:
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generating a voltage at a pin to obtain a first voltage value; decreasing the voltage at the pin; and counting clock cycles from a beginning of said decreasing until the voltage at the pin reaches a second voltage value to obtain a first number, wherein the first number corresponds to a first time period; wherein the first time period corresponds to identification information of a host system comprising the pin. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A system comprising:
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a pin; an RC circuit comprising a resistor and a capacitor coupled in series between a supply voltage and a reference voltage, wherein the pin is coupled to a common node coupling the resistor to the capacitor; a comparator configured to compare a threshold voltage with a pin voltage developed at the pin, and to generate a first signal indicative of whether the pin voltage has reached the threshold voltage; and a control circuit configured to receive the first signal and operable to count a first number of clock cycles corresponding to a first time period it takes for the pin voltage to reach the threshold voltage from a value of the supply voltage; wherein the first time period corresponds to a time constant of the RC circuit, wherein the time constant of the RC circuit is representative of hardware identification information of the system. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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Specification