Difference capture timer
First Claim
1. A difference capture circuit for obtaining the duration of a digital signal pulse characterized by a first event and a second event, said difference capture circuit including an incoming signal node for receiving the digital signal pulse, said difference capture circuit comprising:
- a. a counter-initiate circuit coupled between said incoming signal node and a counter, wherein the counter is coupled to a system clock; and
b. a triggering circuit coupled between said incoming signal node and a capture register,wherein the first event activates said counter-initiate circuit such that the counter begins to count pulses associated with the system clock, wherein the second event activates said triggering circuit such that said capture register fetches a count from the counter upon the occurrence of the second event, and wherein the count fetched from the counter is directly related to the difference in time between the first event and the second event.
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Abstract
A difference capture circuit for determining the duration of a digital signal pulse. The difference circuit includes a branch couplable to a standard counter for activating the counter to count as a function of a system clock pulse, and a triggering circuit couplable to a standard capture register for fetching the count from the counter. The difference capture circuit may be incorporated into standard timer unit circuitry and is designed to calculate the difference between either the rise and fall times for an incoming signal, or the rise to rise time of that signal. Adding the difference capture circuit to a timing unit eliminates the need to use RAM, and minimizes processor resources, in obtaining the timing associated with a signal change.
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Citations
8 Claims
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1. A difference capture circuit for obtaining the duration of a digital signal pulse characterized by a first event and a second event, said difference capture circuit including an incoming signal node for receiving the digital signal pulse, said difference capture circuit comprising:
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a. a counter-initiate circuit coupled between said incoming signal node and a counter, wherein the counter is coupled to a system clock; and b. a triggering circuit coupled between said incoming signal node and a capture register, wherein the first event activates said counter-initiate circuit such that the counter begins to count pulses associated with the system clock, wherein the second event activates said triggering circuit such that said capture register fetches a count from the counter upon the occurrence of the second event, and wherein the count fetched from the counter is directly related to the difference in time between the first event and the second event. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification