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 configured 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;
wherein the third circuit is configured to signal an error condition when the pin voltage does not reach the first voltage value within a specified time period.
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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
26 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 configured 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; wherein the third circuit is configured to signal an error condition when the pin voltage does not reach the first voltage value within a specified time period. - 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; counting clock cycles from a beginning of said decreasing; obtaining a first number if a specified number of clock cycles is not reached before the voltage at the pin reaches a second voltage value, 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; and signaling an error condition if the specified number of clock cycles is reached before the voltage at the pin reaches the second voltage value. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. 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 further configured 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 further configured to count a specified number of clock cycles; wherein the control circuit is configured to store a first value corresponding to a first number of clock cycles corresponding to a first time period taken for the pin voltage to reach the threshold voltage from a value of the supply voltage, when the control circuit reaches the first number of clock cycles before reaching the specified number of clock cycles, wherein the first value 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; and wherein the control circuit is configured to signal an error condition when the control circuit reaches the specified number of clock cycles before reaching the first number of clock cycles. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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Specification