Emulation system with time-multiplexed interconnect

• US 6,377,912 B1
• Filed: 08/13/1999
• Issued: 04/23/2002
• Est. Priority Date: 05/30/1997
• Status: Expired due to Term

• Current Assignee: Cadence Design Systems Incorporated (Cadence Group)
• Original Assignee: Quickturn Design Systems Incorporated (Cadence Group)
• Inventors: Butts, Michael R., Bershteyn, Mikhail, Sample, Stephen P., Bauer, Jerry R.
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): Broda, Samuel
• Application Number:
  US09/374,444
• Time in Patent Office: 984 Days
• Field of Search: 703/13, 703/24, 703/25, 703/26, 703/27, 703/28, 716/1, 716/5, 716/17
• US Class Current: 703/28
• CPC Class Codes: G01R 31/2853 Electrical testing of internal connections or -isolation, e.g. latch-up or chip-to-lead connections G01R31/31717 takes precedence; test of chip-to-PCB or lead-to-PCB connections G01R31/66
• CPC Class Codes: G01R 31/31717 Interconnect testing by scan techniques see G01R31/31855
• CPC Class Codes: G06F 30/331 with hardware acceleration, e.g. by using field programmable gate array [FPGA] or emulation
• CPC Class Codes: Y10S 370/916 Multiplexer/demultiplexer

Abstract

A hardware emulation system is disclosed which reduces hardware cost by time-multiplexing multiple design signals onto physical logic chip pins and printed circuit board. The reconfigurable logic system of the present invention comprises a plurality of reprogrammable logic devices, and a plurality of reprogrammable interconnect devices. The logic devices and interconnect devices are interconnected together such that multiple design signals share common pins and circuit board traces. A logic analyzer for a hardware emulation system is also disclosed. The logic circuits necessary for executing logic analyzer functions is programmed into the programmable resources in the logic chips of the emulation system.

Claims

1. An electrically reconfigurable logic assembly for use in an electrically reconfigurable hardware emulation system which can be configured with a circuit design in response to the input of circuit information, said electrically reconfigurable logic assembly comprising:

a plurality of reprogrammable logic devices disposed on a printed circuit board, each of said reprogrammable logic devices having logic elements capable of implementing combinatorial logic elements and sequential logic elements, said reprogrammable logic devices also comprising an input demultiplexer and an output multiplexer implemented at at least one input/output terminal, said input demultiplexer receiving a time-multiplexed signal and dividing said time-multiplexed signal into one or more internal signals, said output multiplexer combining one or more internal signals onto a first single physical interconnection, said reprogrammable logic devices further comprising a first clock divider, said clock divider receiving a multiplexing clock signal;

a plurality of reprogrammable interconnect devices disposed on said printed circuit board, said plurality of reprogrammable interconnect devices comprising an input demultiplexer and an output multiplexer implemented at at least one input/output terminal of said plurality of reprogrammable interconnect devices, said input demultiplexer receiving a time-multiplexed input signal and dividing it into one or more component signals, said output multiplexer combining said one or more component signals or other component signals onto a second single physical interconnection, each of said plurality of reprogrammable interconnect devices comprising configurable interconnect circuitry which places said input demultiplexers in electrical communication with said output multiplexers, said reprogrammable interconnect devices further comprising a second clock divider, said clock divider receiving said multiplexing clock signal; and

a set of fixed electrical conductors of said printed circuit board connecting said programmable input/output terminals on said reprogrammable logic devices to said input/output terminals on said reprogrammable interconnect devices such that each of said reprogrammable interconnect devices is connected to at least one but not all of said programmable input/output terminals on each of said reprogrammable logic devices.

2. An electrically reconfigurable logic assembly as recited in claim 1, wherein said reprogrammable logic devices comprise programmable gate arrays.

3. An electrically reconfigurable logic assembly as recited in claim 1, wherein said reprogrammable logic devices comprise field programmable gate arrays.

4. An electrically reconfigurable logic assembly as recited in claim 1 wherein said reprogrammable interconnect devices comprise field programmable gate arrays.

5. An electrically reconfigurable logic assembly as recited in claim 1, wherein said reprogrammable interconnect devices comprise an integrated circuit having an array of crosspoint switches fabricated thereon.

6. An electrically reconfigurable logic assembly as recited in claim 1 wherein said input demultiplexer of said plurality of reprogrammable logic devices comprises at least two sequential logic elements.

7. An electrically reconfigurable logic assembly as recited in claim 6 wherein said at least two sequential logic elements comprise flip-flops.

8. An electrically reconfigurable logic assembly as recited in claim 6 wherein said at least two sequential logic elements are clocked by said multiplexing clock signal.

9. An electrically reconfigurable logic assembly as recited in claim 1 wherein said output multiplexer of said plurality of reprogrammable logic devices comprises at least two sequential logic elements wherein respective outputs of each of said at least two sequential logic elements are input to a multiplexer.

10. An electrically reconfigurable logic assembly as recited in claim 9 wherein said at least two sequential logic elements comprise flip-flops, each of said flip-flops having a data input, an enable input, a clock input and an output.

11. An electrically reconfigurable logic assembly as recited in claim 10 wherein said clock input of each of said flip-flops receive said multiplexing clock signal, wherein said enable input of each of said flip-flops receive an output of said first clock divider.

12. An electrically reconfigurable logic assembly as recited in claim 1 wherein said input demultiplexer of said plurality of reprogrammable interconnect devices comprises at least two sequential logic elements.

13. An electrically reconfigurable logic assembly as recited in claim 12 wherein said at least two sequential logic elements comprise flip-flops.

14. An electrically reconfigurable logic assembly as recited in claim 13 wherein said at least two sequential logic elements are clocked by said an output of said second clock divider.

15. An electrically reconfigurable logic assembly as recited in claim 1 wherein said output multiplexer of said plurality of reprogrammable logic devices comprises a multiplexer, said multiplexer comprising at least two inputs and a select input.

16. An electrically reconfigurable logic assembly as recited in claim 15 wherein said select input of said multiplexer receives an output of said second clock divider.

17. An electrically reconfigurable logic assembly as recited in claim 1 wherein said multiplexing clock signal is asynchronous to other signals within said plurality of reprogrammable logic devices and said plurality of reprogrammable interconnect devices.

18. An electrically reconfigurable logic assembly as recited in claim 1 wherein said input demultiplexer and said output multiplexer implemented at said at least one input/output terminal is programmed into said plurality of reprogrammable logic devices.

19. An electrically reconfigurable logic assembly as recited in claim 1 wherein said input demultiplexer and said output multiplexer implemented at said at least one input/output terminal is fabricated into said plurality of reprogrammable logic devices.

20. An electrically reconfigurable logic assembly as recited in claim 1 wherein said input demultiplexer and said output multiplexer implemented at said at least one input/output terminal is programmed into said plurality of reprogrammable interconnect devices.

21. An electrically reconfigurable logic assembly as recited in claim 1 wherein said input demultiplexer and said output multiplexer implemented at said at least one input/output terminal is fabricated into said plurality of reprogrammable interconnect devices.

22. An electrically reconfigurable logic assembly for use in an electrically reconfigurable hardware emulation system having a user'"'"'s circuit design implemented therein, said electrically reconfigurable logic assembly comprising:

a plurality of reprogrammable logic devices installed on a printed circuit board, each of said reprogrammable logic devices having internal circuitry which can be reprogrammably configured to provide at least combinatorial logic elements and sequential logic elements, said reprogrammable logic devices also comprising an input demultiplexer and an output multiplexer implemented at at least one input/output terminal, said input demultiplexer receiving a time-multiplexed signal and dividing said time-multiplexed signal into one or more internal signals, said output multiplexer combining one or more internal signals onto a first single physical interconnection, said reprogrammable logic devices further comprising a first clock divider, said clock divider receiving a multiplexing clock signal;

a plurality of reprogrammable interconnect devices disposed on said printed circuit board, said plurality of reprogrammable interconnect devices comprising an input demultiplexer and an output multiplexer implemented at at least one input/output terminal of said plurality of reprogrammable interconnect devices, said input demultiplexer receiving a time-multiplexed input signal and dividing it into one or more component signals, said output multiplexer combining said one or more component signals or other component signals onto a second single physical interconnection, each of said plurality of reprogrammable interconnect devices comprising configurable interconnect circuitry which places said input demultiplexers in electrical communication with said output multiplexers, said reprogrammable interconnect devices further comprising a second clock divider;

said clock divider receiving said multiplexing clock signal; and

a set of fixed electrical conductors of said printed circuit board, said set of fixed electrical conductors interconnecting said reprogrammable logic devices to said reprogrammable interconnect devices with a partial crossbar architecture.

23. An electrically reconfigurable logic assembly as recited in claim 22, wherein said reprogrammable logic devices comprise programmable gate arrays.

24. An electrically reconfigurable logic assembly as recited in claim 22, wherein said reprogrammable logic devices comprise field programmable gate arrays.

25. An electrically reconfigurable logic assembly as recited in claim 22 wherein said reprogrammable interconnect devices comprise programmable gate arrays.

26. An electrically reconfigurable logic assembly as recited in claim 22, wherein said reprogrammable interconnect devices comprise field programmable gate arrays.

27. An electrically reconfigurable logic assembly as recited in claim 22, wherein said reprogrammable interconnect devices comprise an integrated circuit having an array of crosspoint switches fabricated thereon.

28. An electrically reconfigurable logic assembly as recited in claim 22 wherein said input demultiplexer of said plurality of reprogrammable logic devices comprises at least two sequential logic elements.

29. An electrically reconfigurable logic assembly as recited in claim 28 wherein said at least two sequential logic elements comprise flip-flops.

30. An electrically reconfigurable logic assembly as recited in claim 28 wherein said at least two sequential logic elements are clocked by said multiplexing clock signal.

31. An electrically reconfigurable logic assembly as recited in claim 22 wherein said output multiplexer of said plurality of reprogrammable logic devices comprises at least two sequential logic elements wherein respective outputs of each of said at least two sequential logic elements are input to a multiplexer.

32. An electrically reconfigurable logic assembly as recited in claim 31 wherein said at least two sequential logic elements comprise flip-flops, each of said flip-flops having a data input, an enable input, a clock input and an output.

33. An electrically reconfigurable logic assembly as recited in claim 32 wherein said clock input of each of said flip-flops receive said multiplexing clock signal, wherein said enable input of each of said flip-flops receive an output of said first clock divider.

34. An electrically reconfigurable logic assembly as recited in claim 22 wherein said input demultiplexer of said plurality of reprogrammable interconnect devices comprises at least two sequential logic elements.

35. An electrically reconfigurable logic assembly as recited in claim 34 wherein said at least two sequential logic elements comprise flip-flops.

36. An electrically reconfigurable logic assembly as recited in claim 35 wherein said at least two sequential logic elements are clocked by said an output of said second clock divider.

37. An electrically reconfigurable logic assembly as recited in claim 22 wherein said output multiplexer of said plurality of reprogrammable logic devices comprises a multiplexer, said multiplexer comprising at least two inputs and a select input.

38. An electrically reconfigurable logic assembly as recited in claim 37 wherein said select input of said multiplexer receives an output of said second clock divider.

39. An electrically reconfigurable logic assembly as recited in claim 22 wherein said multiplexing clock signal is asynchronous to other signals within said plurality of reprogrammable interconnect devices and said plurality of reprogrammable interconnect devices.

40. An electrically reconfigurable logic assembly as recited in claim 22 wherein said input/output pins on each of said plurality of reprogrammable logic devices are divided into N subsets, were N is an integer.

41. An electrically reconfigurable logic assembly as recited in claim 40 wherein said plurality of reprogrammable interconnect devices comprises N reprogrammable interconnect devices.

42. An electrically reconfigurable logic assembly as recited in claim 22 wherein said input demultiplexer and said output multiplexer implemented at said at least one input/output terminal is programmed into said plurality of reprogrammable logic devices.

43. An electrically reconfigurable logic assembly as recited in claim 22 wherein said input demultiplexer and said output multiplexer implemented at said at least one input/output terminal is fabricated into said plurality of reprogrammable logic devices.

44. An electrically reconfigurable logic assembly as recited in claim 22 wherein said input demultiplexer and said output multiplexer implemented at said at least one input/output terminal is programmed into said plurality of reprogrammable interconnect devices.

45. An electrically reconfigurable logic assembly as recited in claim 22 wherein said input demultiplexer and said output multiplexer implemented at said at least one input/output terminal is fabricated into said plurality of reprogrammable interconnect devices.