ANTI-TEARING PROTECTION SYSTEM FOR NON-VOLATILE MEMORIES

• US 20200133765A1
• Filed: 10/17/2019
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: EM Microelectronic - Marin SA (The Swatch Group AG)
• Original Assignee: EM Microelectronic - Marin SA (The Swatch Group AG)
• Inventors: NOVAK, Tomas, MARINELLI, Filippo
• Granted Patent: US 11,392,449 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 11/1004 to protect a block of data words, e.g. CRC or checksum G06F11/1076 takes precedence; security arrangements for protecting computers or computer systems against unauthorized activity G06F21/00
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: G06F 11/141 for bus or memory accesses
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: G11C 13/004 Reading or sensing circuits or methods
• CPC Class Codes: G11C 16/26 Sensing or reading circuits; Data output circuits

Abstract

The present invention concerns an anti-tearing protection system (1) for a non-volatile memory (3) comprising a first memory block (5) and a second memory block (7), the first and second memory blocks (5, 7) being arranged to store a data set comprising user data and an error detection code obtained based on the user data. The first and second memory blocks (5, 7) can be read in a first read mode for determining logic states of data elements comprised in the data set according to the first read mode. The user data in a respective memory block are considered to be correct according to the first read mode if its error detection code equals a first given value. The first and second memory blocks (5, 7) can further be read in a second read mode for determining the logic states of the data elements comprised in data set according to the second read mode. The user data in a respective memory block are considered to be correct according to the second read mode if its error detection code equals the first given value and if the user data as read in the second read mode are determined to be identical to the user data as read in the first read mode. A third read mode may also be defined. The first read mode may be considered to be a normal read mode, while the second and third read modes may be used to determine if data were strongly written and erased, respectively.

Claims

1. Anti-tearing protection system (1) of a non-volatile memory unit (3), which comprises a first memory block (5) and a second memory block (7), the first and second memory blocks (5, 7) being intended to store a data set comprising user data and an error detection code obtained based on the user data, the first and second memory blocks (5, 7) being arranged to be read in a first read mode defining a first rule set for determining logic states of data elements comprised in the data set according to the first read mode, the user data in a respective memory block are considered to be correct according to the first read mode if its error detection code equals a first given value, said first rule set comprising a first memory read threshold (13),

the system being characterised in that the first and second memory blocks (5, 7) being further arranged to be read in a second read mode defining a second rule set for determining the logic states of the data elements comprised in the data set according to the second read mode, said second rule set comprising a second memory read threshold (15), wherein a processing unit (9) of the system (1) is configured to read both the first and second memory blocks (5, 7), and wherein in the processing unit (9), the user data in a respective memory block are considered to be correct according to the second read mode if its error detection code equals the first given value and if the user data as read in the second read mode are determined to be identical to the user data as read in the first read mode, wherein the data set further comprises counter data indicating which memory block (5, 7) was updated last, and wherein the error detection code is further obtained based on the counter data, and wherein the correctness of the user data is arranged to be used for determining which one of the first and second memory blocks (5, 7) should be updated next by a memory write unit (11) of the system (1).

2. Anti-tearing protection system (1) according to claim 1, wherein if a given property linked to a data element equals to or is above the first read threshold (13), then the data element has a first logic state according to the first read mode, while if the given property is below the first read threshold, then the data element has a second, different logic state according to the first read mode, and wherein if the given property is equals to or is above the second read threshold (15), then the data element has a first logic state according to the second read mode, while if the given property is below the second read threshold (15), then the data element has the second logic state according to the second read mode.

3. Anti-tearing protection system (1) according to claim 2, wherein the given property is derivable from a memory cell level.

4. Anti-tearing protection system according to claim 1, wherein the first and second memory blocks (5, 7) are further arranged to be read in a third read mode defining a third rule set, different from the first and second rule sets, for determining logic states of the data elements comprised in the data set according to the third read mode, and wherein the user data in the respective memory block are considered to be correct according to the third read mode if its error detection code equals the first given value and if the user data as read in the third read mode are determined to be identical to the user data as read in the first read mode.

5. Anti-tearing protection system (1) according to claim 1, wherein the first given value equals the error detection code stored in the respective memory block (5, 7) during a previous memory write operation.

6. Anti-tearing protection system (1) according to claim 1, wherein a further condition for the user data correctness according to the first and second read modes is that the counter data have a given counter value.

7. Integrated circuit card comprising the anti-tearing protection system (1) according to claim 1.

8. Method of operating the anti-tearing protection system (1) according to claim 1, wherein if :

the data set in the first memory block (5) is determined to be correct according to the first read mode, and the data set in the first memory block (5) is determined to be correct according to the second read mode; and

the data set in the second memory block (7) is determined to be correct according to the first read mode, and the data set in the second memory block (7) is determined to be correct according to the second read mode,

then wherein the data set further comprises counter data indicating which memory block (5, 7) was updated last, and wherein the error detection code is further obtained based on the counter data, determining that a valid memory block is the one which was last updated, and updating the first updated memory block with another set of data.

9. Method of operating the anti-tearing protection system (1) according to claim 1, wherein if :

the data set in the first memory block (5) is determined to be correct according to the first read mode, and the data set in the first memory block (5) is determined to be correct according to the second read mode; and

the data set in the second memory block (7) is determined to be correct according to the first read mode, and the data set in the second memory block (7) is determined to be incorrect according to the second read mode,

then determining that the first memory block is valid, and updating the second memory block (7) with another set of data.

10. Method of operating the anti-tearing protection system (1) according to claim 1, wherein if :

the data set in the first memory block (5) is determined to be correct according to the first read mode; and

the data set in the second memory block (7) is determined to be incorrect according to the first read mode, then determining that the first memory block (5) is valid, and updating the second memory block (7) with another set of data.

11. Method of operating the anti-tearing protection system (1) according to claim 1, wherein if :

the data set in the first memory block (5) is determined to be correct according to the first read mode, and the data set in the first memory block (5) is determined to be incorrect according to the second read mode; and

the data set in the second memory block (7) is determined to be correct according to the first read mode, and the data set in the second memory block (7) is determined to be incorrect according to the second read mode,

then wherein the data set further comprises counter data indicating which memory block (5, 7) was updated last, and wherein the error detection code is further obtained based on the counter data, determining that a valid memory block is the one which was first updated, and updating the last updated memory block with another set of data.

12. Method of operating the anti-tearing protection system (1) according to claim 1, wherein if :

the data set in the first memory block (5) is determined to be incorrect according to the first read mode; and

the data set in the second memory block (7) is determined to be incorrect according to the first read mode, then determining that the first and second memory blocks (5, 7) are invalid.

13. Method according to claim 12, wherein the method further comprises preventing a further write operation to the first and second memory blocks (5, 7).