Using transfer bits during data transfer from non-volatile to volatile memories

• US 6,981,091 B2
• Filed: 10/25/2001
• Issued: 12/27/2005
• Est. Priority Date: 10/25/2001
• Status: Active Grant

• Current Assignee: Xilinx, Inc. (Advanced Micro Devices, Inc.)
• Original Assignee: Xilinx, Inc. (Advanced Micro Devices, Inc.)
• Inventors: Shimanek, Schuyler E., Darling, Roy D.
• Primary Examiner(s): Tran, Denise
• Application Number:
  US10/040,001
• Publication Number:
  US 20030084230A1
• Time in Patent Office: 1,524 Days
• Field of Search: 365/185.22, 365/189.07, 365/185.14, 365/185.29, 365/218, 711/101, 711/103, 711/170, 713/1, 714/725, 714/763, 714/819
• US Class Current: 711/103
• CPC Class Codes: G11C 11/005 comprising combined but independently operative RAM-ROM, RAM-PROM, RAM-EPROM cells
• CPC Class Codes: G11C 16/225 Preventing erasure, programming or reading when power supply voltages are outside the required ranges
• CPC Class Codes: G11C 7/24 Memory cell safety or protection circuits, e.g. arrangements for preventing inadvertent reading or writing; Status cells; Test cells

Abstract

Structures and methods for transferring data from non-volatile to volatile memories. An extra bit, called a “transfer bit”, is included in each data word. The transfer bit is set to the programmed value, and is monitored by a control circuit during the memory transfer. If the supply voltage is sufficient for correct programming, the transfer bit is read as “programmed”, and the data transfer continues. If the supply voltage is below the minimum supply voltage for proper programming, the transfer bit is read as “erased”, and the data transfer is reinitiated. In one embodiment, a second transfer bit set to the “erased” value is included in each word.

Claims

1. A method of configuring a programmable logic device including non-volatile and volatile memories, the non-volatile memory including a plurality of words comprising configuration data for the programmable logic device, each word including a first transfer bit having a first stored value that is one of a “

programmed”

value and an “

erased”

value, the method comprising;

powering up the programmable logic device;

setting a latch to a predetermined initialization value while powering up the programmable logic device;

repeating the following sequence for a series of the words in the non-volatile memory, from a first word to a final word;

transferring one of the words from the non-volatile memory to the volatile memory, and

detecting a first detected value of the first transfer bit transferred from the non-volatile memory to the volatile memory;

repeating, if the first detected value is different from the first stored value for any one word, transferring the first word from the non-volatile memory to the volatile memory; and

for each transferred word, changing a value in the latch from the predetermined initialization value, if the first detected value is different from the first stored value.

2. The method of claim 1, further comprising:

beginning operation of the programmable logic device after the final word is transferred and detected, if the first detected value for each word is the same as the first stored value for the same word.

3. The method of claim 1, further comprising:

storing the plurality of words in the non-volatile memory prior to powering up the programmable logic device.

4. The method of claim 1, wherein the first transfer bit is in the same location of each word.

5. The method of claim 1, wherein each word further includes a second transfer bit having a second stored value, the second stored value being different from the first stored value.

6. The method of claim 5, further comprising:

for each transferred word, detecting a second detected value of the second transfer bit transferred from the non-volatile memory to the volatile memory; and

repeating, if the second detected value is different from the second stored value for any one word, transferring the first word from the non-volatile memory to the volatile memory.

7. The method of claim 1, wherein the programmable logic device is a CPLD.

8. The method of claim 1, wherein repeating transferring the first word is performed only after transferring the final word.

9. The method of claim 1, wherein repeating transferring the first word is performed after detecting a first detected value and before transferring the final word.

10. An apparatus for configuring a programmable logic device including non-volatile and volatile memories, the non-volatile memory including a plurality of words comprising configuration data for the programmable logic device, each word including a first transfer bit having a first stored value that is one of a “

programmed”

value and an “

erased”

value, the apparatus comprising;

means for powering up the programmable logic device;

means for setting a latch to a predetermined initialization value while powering up the programmable logic device;

means for transferring each of the words from the non-volatile memory to the volatile memory, in a sequence of words from a first word to a final word;

means for detecting for each word a first detected value of the first transfer bit transferred from the non-volatile memory to the volatile memory;

means for repeating, if the first detected value is different from the first stored value for any one word, transferring each of the words from the non-volatile memory to the volatile memory and detecting for each word a first detected value; and

means for changing, for each transferred word, a value in the latch from the predetermined initialization value, if the first detected value is different from the first stored value.

11. A method of transferring data from a non-volatile memory to a volatile memory in a circuit, the non-volatile memory including a plurality of words, each word including a first transfer bit having a first stored value that is one of a “

programmed”

value and an “

erased”

value, the method comprising;

powering up the circuit;

setting a latch to a predetermined initialization value while powering up the circuit;

repeating the following sequence in response to the powering up the circuit, for a series of the words in the non-volatile memory, from a first word to a final word;

transferring one of the words from the non-volatile memory to the volatile memory, and

detecting a first detected value of the first transfer bit transferred from the non-volatile memory to the volatile memory;

repeating, if the first detected value is different from the first stored value for any one word, transferring the first word from the non-volatile memory to the volatile memory; and

changing, for each transferred word, a value in the latch from the predetermined initialization value, if the first detected value is different from the first stored value.

12. The method of claim 11, further comprising:

beginning operation of the circuit after the final word is transferred and detected, if the first detected value for each word is the same as the first stored value for the same word.

13. The method of claim 11, further comprising:

storing the plurality of words in the non-volatile memory prior to powering up the circuit.

14. The method of claim 11, wherein the first transfer bit is in the same location of each word.

15. The method of claim 11, wherein each word further includes a second transfer bit having a second stored value, the second stored value being different from the first stored value.

16. The method of claim 15, further comprising:

for each transferred word, detecting a second detected value of the second transfer bit transferred from the non-volatile memory to the volatile memory; and

repeating, if the second detected value is different from the second stored value for any one word, transferring the first word from the non-volatile memory to the volatile memory.

17. The method of claim 11, wherein the circuit is an integrated circuit (IC).

18. The method of claim 11, wherein the circuit is a programmable logic device.

19. The method of claim 11, wherein the programmable logic device is a CPLD.

20. The method of claim 11, wherein repeating transferring the first word is performed only after transferring the final word.

21. The method of claim 11, wherein repeating transferring the first word is performed after detecting a first detected value and before transferring the final word.

22. An apparatus for transferring data from a non-volatile memory to a volatile memory in a circuit, the non-volatile memory including a plurality of words, each word including a first transfer bit having a first stored value that is one of a “

programmed”

value and an “

erased”

value, the apparatus comprising;

means for powering up the circuit;

means for setting a latch to a predetermined initialization value while powering up the circuit;

means for transferring each of the words from the non-volatile memory to the volatile memory, in a sequence of words from a first word to a final word;

means for detecting for each word a first detected value of the first transfer bit transferred from the non-volatile memory to the volatile memory;

means for repeating, if the first detected value is different from the first stored value for any one word, transferring each of the words from the non-volatile memory to the volatile memory and detecting for each word a first detected value; and

means for changing, for each transferred word, a value in the latch from the predetermined initialization value, if the first detected value is different from the first stored value.