High performance self modifying on-the-fly alterable logic FPGA, architecture and method

• US 5,838,165 A
• Filed: 08/21/1996
• Issued: 11/17/1998
• Est. Priority Date: 08/21/1996
• Status: Expired due to Term

• Current Assignee: NeoRam, LLC
• Original Assignee: Mukesh Chatter
• Inventors: Chatter, Mukesh
• Primary Examiner(s): Tokar, Michael J.
• Assistant Examiner(s): ROSEEN, RICHARD R
• Application Number:
  US08/700,966
• Time in Patent Office: 818 Days
• Field of Search: 365/236, 326/38-41
• US Class Current: 326/38
• CPC Class Codes: G06F 15/7867 with reconfigurable architecture

Abstract

A technique for configuring arrays of programmable logic cells, including those associated with FPGA devices, through a novel DRAM-based configuration control structure that enables not only "on-the-fly" alterable chip and similar device reconfigurations, but, where desired, self-modifying reconfigurations for differing functionalities of the devices, eliminating current serious reconfigurability limitations and related problems, while providing significantly enhanced system performance at low cost. A large amount of memory is available internal to the FPGA and is accessed with a small number of pins such that the reconfiguration time is, for example, four orders of magnitude faster than the traditional approaches and at notably low cost.

Claims

1. A method of configuring an array of programmable logic cells each having logic functions controlled by an associated configuration bit memory that comprises, storing bit information defining multiple program configurations in a DRAM core;

connecting a bus to the array to enable a DRAM row wide loading of the configuration bit memories of the cells with bit information defining a desired configuration; and

, upon a configuration command, retrieving from the DRAM core, at least a row at a time, the configuration bit information, and loading such information in the bit memories of the cells to control the corresponding cell logic functions to achieve the desired configuration programming, and in which, upon completion of a function by the array of logic cells, a bit command is generated to indicate a new desired functionality of the array; and

a supplemental memory core is provided containing the bit address of a DRAM row and connected to be responsive to the next functionality bit command and correspondingly to drive the DRAM, retrieving and loading the configuration bit information representing said next functionality in the bit memories of the cells, controlling the corresponding cell logic functions and thereby self-reconfiguring the array to perform the next functionality.

2. A method as claimed in claim 1 wherein said self reconfigurability continues automatically for subsequent desired functionality commands.

3. A method as claimed in claim 1 and in which new configuration data is loaded into the DRAM core while the device is operating.

4. A method of configuring an array of programmable logic cells each having logic functions controlled by an associated configuration bit memory, that comprises, storing bit information defining multiple program configurations in a DRAM core;

connecting a bus to the array to enable a DRAM row wide loading of the configuration bit memories of the cells with bit information defining a desired configuration; and

, upon a configuration command, retrieving from the DRAM core, at least a row at a time, the configuration bit information, and loading such information in the bit memories of the cells to control the corresponding cell logic functions to achieve the desired configuration programming, and in which the DRAM core is also used as storage space accessible from both external I/O interfacing and internal logic.

5. A method as claimed in claim 4 and in which the row-at-a-time retrieval and loading enables re-configuration on-the-fly.

6. A method as claimed in claim 4 and in which the array comprises an FPGA device, and the logic cell bit memories comprise SRAM distributed bits.

7. A method as claimed in claim 6 and in which reconfiguration is effected by loading only those SRAM rows of bits which need to be changed.

8. A method as claimed in claim 4 and in which, during external interfacing, the internal row wide bus stores/retrieves a maximum of row wide data in one access;

and, once a row has been internally selected, rapidly accessing column data.

9. Apparatus for configuring an array of programmable logic cells each having logic functions controlled by an associated configuration bit memory, the apparatus having, in combination, a DRAM core for storing bit information defining multiple program configurations;

a bus interconnecting the array and the DRAM core such as to enable a DRAM row wide loading of the configuration bit memories of the array of logic cells with bit information defining a desired configuration;

means for generating a configuration command; and

, upon such configuration command, and responsive thereto, means for retrieving from the DRAM core, at least a row at a time, the configuration bit information; and

means for loading such information in said bit memories of the logic cells to control the corresponding cell logic functions to achieve the desired configuration programming, and in which an access control circuit is provided connected to input the DRAM core and connected to one or both of a DRAM arbitration and refresh logic module responsive to a configuration command internally emanating from the array of logic cells, and an external DRAM interface.

10. Apparatus as claimed in claim 9 and in which the array comprise, an FPGA device, and the logic cell bit memories comprise SRAM distributed bits.

11. Apparatus as claimed in claim 10 and in which reconfiguration is effected, wherein the loading means load only those SRAM rows of bits which need to be changed.

12. Apparatus as claimed in claim 9 and in which the array is part of a programmable device and new configuration data is loaded into the DRAM core while the device is operating.

13. Apparatus as claimed in claim 12 and in which the device includes an FPGA.

14. Apparatus as claimed in claim 9 and in which the row-at-a-time retrieval and loading enables re-configuration on-the-fly.

15. Apparatus as claimed in claim 9 and in which two identical banks of DRAMS are provided with identical configuration data loaded into each.

16. Apparatus for configuring an array of programmable logic cells each having logic functions controlled by an associated configuration bit memory, the apparatus having, in combination, a DRAM core for storing the information defining multiple program configurations:

a bus interconnecting the array and the DRAM core such as to enable a DRAM row wide loading of the configuration bit memories of the array of logic cells with bit information defining a desired configuration;

means for generating a configuration command; and

, upon such configuration command, and responsive thereto, means for retrieving from the DRAM core, at least a row at a time, the configuration bit information, and means for loading such information in said bit memories of the logic cells to control the corresponding cell logic functions to achieve the desired configuration programming, and in which an access control circuit is provided connected to input the DRAM core and responsive to data bits corresponding to a DRAM row address emanating from an SRAM memory core unit containing data width equal to the number of bits required to decode DRAM row addresses uniquely, thereby to drive the selected row addresses of the DRAM internally, and with the SRAM unit connected to receive address bit configuration command signals from the array of logic cells.

17. Apparatus as claimed in claim 16 and in which the said configuration command signal is generated upon completion of a function by the array of logic cells, as a new configuration for a next desired functionality of the array;

and, upon the designated DRAM row address, correspondingly decoding the DRAM core from the access control means;

means for loading the configuration bit information representing said next functionality, as returned from the DRAM core, in the bit memories of the logic cells, thereby to control the corresponding cell logic functions and thus self-reconfiguring the array to perform the next functionality, with said self-reconfiguring continuing automatically for subsequent desired functionality commands.

18. Apparatus as claimed in claim 17 and in which the logic cell array generates 5 address bits and the SRAM unit generates 9 data bits corresponding to a DRAM row address, the SRAM unit containing 32×

9 bits.

19. Apparatus for configuring an array of programmable logic cells each having logic functions controlled by an associated configuration bit memory, the apparatus having, in combination, a DRAM core for storing bit information defining multiple program configurations;

a bus interconnecting the array and the DRAM core such as to enable a DRAM row wide loading of the configuration bit memories of the array of logic cells with bit information defining a desired configuration;

means for generating a configuration command; and

, upon such configuration command, and responsive thereto, means for retrieving from the DRAM core, at least a row at a time, the configuration bit information, and means for loading such information in said bit memories of the logic cells to control the corresponding cell logic functions to achieve the desired configuration programming, and in which, the logic cell array, upon completion of a function, generates a bit command to indicate a next desired functionality of the array; and

there is further provided a supplemental memory core containing the bit address of a DRAM row and connected between the array and the DRAM core to respond to said next functionality bit command and correspondingly to drive the DRAM to retrieve and load the configuration bit information representing said next functionality in the bit memories of the cells of the array, to control the corresponding cell logic functions, thereby to enable self-reconfiguration of the array to perform said next functionality.

20. Apparatus as claimed in claim 19 and in which the supplemental memory core comprises a SRAM core.

21. Apparatus as claimed in claim 19 and in which said self-reconfiguration continues automatically for subsequent desired functionality commands.

22. Apparatus for configuring an array of programmable logic cells each having logic functions controlled by an associated configuration bit memory, the apparatus having, in combination, a DRAM core for storing bit information defining multiple program configurations;

a bus interconnecting the array and the DRAM core such as to enable a DRAM row wide loading of the configuration bit memories of the array of logic cells with bit information defining a desired configuration;

means for generating a configuration command; and

, upon such configuration command, and responsive thereto, means for retrieving from the DRAM core, at least a row at a time, the configuration bit information; and

means for loading such information in said bit memories of the logic cells to control the corresponding cell logic functions to achieve the desired configuration programming, and in which the DRAM core is also used as storage space accessible from both external I/O interfacing and internal logic.

23. Apparatus as claimed in claim 22 and in which, during external interfacing, the internal row wide bus stores/retrieves a maximum of row wide data in one access;

and, once a row has been internally selected, means is provided for rapidly accessing column data.

24. Apparatus for configuring an array of programmable logic cells each having logic functions controlled by an associated configuration bit memory, the apparatus having, in combination, a DRAM core for storing bit information defining multiple program configurations;

a bus interconnecting the array and the DRAM core such as to enable a DRAM row wide loading of the configuration bit memories of the array of logic cells with bit information defining a desired configuration;

means for generating a configuration command; and

, upon such configuration command, and responsive thereto, means for retrieving from the DRAM core, at least a row at a time, the configuration bit information; and

means for loading such information in said bit memories of the logic cells to control the corresponding cell logic functions to achieve the desired configuration programming, and in which the array comprises an FPGA device, and the logic cell bit memories comprises SRAM distributed bits, and in which two identical banks of DRAMs are provided with identical configuration data loaded into each, and in which when one bank is having its DRAM core(s) refreshed, the other provides the configuration data.