Autoranging time stamp circuit

A circuit for associating time values with specified events stored in a memory, comprising:

• means for generating a plurality of different known clock frequencies;
• a multiplexer for selecting in order of decreasing frequency the clock frequencies to provide a clock signal;
• means for generating in response to the clock signal a binary code count to be associated as a time value with each specified event to be stored;
• means for signaling the occurrence of a specified event;
• and
• control means responsive to the signaling means to reset the clock frequency to its initial frequency in the predetermined order each time a specified event occurs.

In a data acquisition system that stores specified events in memory, a circuit for associating a time value with each specified event that is stored for measuring the time between the events, the circuit comprising:

• an oscillator providing a clock frequency;
• a plurality of counters clocked by the oscillator and connected in cascade to divide the oscillator frequency, each counter generating a clock signal of predetermined frequency, the frequencies having a decreasing order;
• a plurality of counter programmable logic arrays for generating a Gray code count, the count generated in response to a clock signal provided by one of the predetermined frequencies;
• a multiplexer for selecting in response to a portion of the Gray code count the clock frequencies in the decreasing order to provide the clock signal to the counter programmable logic arrays;
• and
• a control programmable logic array for sensing the occurrence of a specified event and in response resetting the Gray code count to an initial count and through the reset of the count resetting the clock frequency to its initial frequency in the predetermined order.

A method of associating a time value with specified events, the events stored in memory, comprising:

• generating a clock signal from a range of clock frequencies;
• generating in response to the clock signal a binary code count to be associated as a time value with each specified event;
• selecting progressively slower clock frequencies as the code count changes;
• signaling the occurrence of a specified event;
• storing the binary code count associated with each specified event;
• and
• resetting the clock frequency to its initial clock frequency each time a specified event occurs.