Method for storing and/or changing state-information of a memory as well as integrated circuit and data carrier
In a method for storing and/or changing state information in a memory ( 2 ) containing a plurality of memory cells ( 3 ), wherein the memory cells ( 3 ) assume an irreversible memory state as a result of a programming step, wherein the state information is represented by a number and/or position of memory cells ( 3 ) that are in an irreversible memory state or are programmed, the state information (S 3 , S 13 ) is determined by checking the memory state of the memory, and then, after selecting (S 4 , S 14 ) an unprogrammed memory cell ( 3 ) the selected memory cell is programmed during or for changing the state information of the memory ( 2 ).
1. An integrated circuit for securing data stored in a data carrier comprising:
a memory comprising a plurality of memory cells;
a first logic circuit configured for determining a current state of the memory, wherein the current state of the memory is selected from the group consisting of an active state and a quiet state and wherein in the active state the data of the carrier is accessible and wherein in the quiet state the data of the carrier is inaccessible;
a feed-logic circuit, wherein the feed-logic circuit is configured for:
receiving state information indicative of a current state of a memory cell, wherein the current state of the memory cell is selected from the group consisting of a programmed state and an unprogrammed state; and
if the current state of the memory is the active state and if the current state of the memory cell is the unprogrammed state, then selecting the memory cell; and
issuing a programming command to a programming unit to program the selected memory cell to change the state of the memory cell to the programmed state, wherein the memory cell assumes an irreversible memory state as a result of the programming and wherein the memory enters the quiet state;
means for returning the memory back to the active state and then resetting the memory to the quiet state by changing the state of a next memory cell of the plurality of memory cells to the programmed state, wherein said next memory cell assumes an irreversible memory state as a result of the programming.
2. The integrated circuit according to claim 1 further comprising:
a counter; and
a sequencing circuit, wherein the sequencing circuit is configured for:
providing a clock signal to a clock input of the integrated circuit via the counter;
receiving a serial output from the integrated circuit indicative of the state of each of the plurality of memory cells; and
issuing a stop count signal to the counter when a first memory cell in the unprogrammed state is detected, and
wherein the counter is configured to count the clock signals to produce a count indicative of the location of the first memory cell in the unprogrammed state.
3. The integrated circuit according to claim 1 further comprising a verification circuit, wherein the verification circuit is configured for, prior to determination of the current state of the memory, verifying authorization to access the memory.
4. An integrated circuit according to claim 1 , wherein the data stored in the data carrier is selected from the group consisting of preset data and data entered via an input device.
5. A data carrier comprising an integrated circuit according to claim 1 .
6. A data carrier according to claim 5 , wherein the data carrier is designed for contactless communication with a communication station.
7. A data carrier according to claim 5 , wherein the data carrier is in the form of a tag or label.
8. The integrated circuit of claim 1 , wherein the active state is associated with an even count of memory cells in the programmed state and wherein the first logic circuit is configured for:
determining a count of memory cells in the programmed state;
if the count of memory cells in the programmed state is even, then determining the current state of the memory to be the active state; and
if the count of memory cells in the programmed state is odd, then determining the current state of the memory to be the quiet state.
9. The integrated circuit of claim 1 , wherein the active state is associated with an odd count of memory cells in the programmed state and wherein the first logic circuit is configured for:
determining a count of memory cells in the programmed state;
if the count of memory cells in the programmed state is odd, then determining the current state of the memory to be the active state; and
if the count of memory cells in the programmed state is even, then determining the current state of the memory to be the quiet state.
10. An integrated circuit for securing data stored in a data carrier comprising:
a memory comprising a plurality of memory cells;
a first logic circuit configured for determining a current state of the memory, wherein the current state of the memory is selected from the group consisting of an active state and a quiet state and wherein in the active state the data of the carrier is accessible and wherein in the quiet state the data of the carrier is inaccessible;
a feed-logic circuit, wherein the feed-logic circuit is configured for:
receiving state information indicative of a current state of a memory cell, wherein the current state of the memory cell is selected from the group consisting of a programmed state and an unprogrammed state; and
if the current state of the memory is the active state and if the current state of the memory cell is the unprogrammed state, then selecting the memory cell; and
issuing a programming command to a programming unit to program the selected memory cell to change the state of the memory cell to the programmed state, wherein the memory cell assumes an irreversible memory state as a result of the programming and wherein the memory enters the quiet state;
wherein the active state is associated with an even count of memory cells in the
programmed state and wherein the first logic circuit is configured for:
determining a count of memory cells in the programmed state;
if the count of memory cells in the programmed state is even, then determining the current state of the memory to be the active state; and
if the count of memory cells in the programmed state is odd, then determining the current state of the memory to be the quiet state.
11. An integrated circuit for securing data stored in a data carrier comprising:
a memory comprising a plurality of memory cells;
a first logic circuit configured for determining a current state of the memory, wherein the current state of the memory is selected from the group consisting of an active state and a quiet state and wherein in the active state the data of the carrier is accessible and wherein in the quiet state the data of the carrier is inaccessible;
a feed-logic circuit, wherein the feed-logic circuit is configured for:
receiving state information indicative of a current state of a memory cell, wherein the current state of the memory cell is selected from the group consisting of a programmed state and an unprogrammed state; and
if the current state of the memory is the active state and if the current state of the memory cell is the unprogrammed state, then selecting the memory cell; and
issuing a programming command to a programming unit to program the selected memory cell to change the state of the memory cell to the programmed state, wherein the memory cell assumes an irreversible memory state as a result of the programming and wherein the memory enters the quiet state;
wherein the active state is associated with an odd count of memory cells in the programmed state and wherein the first logic circuit is configured for:
determining a count of memory cells in the programmed state;
if the count of memory cells in the programmed state is odd, then determining the current state of the memory to be the active state; and
if the count of memory cells in the programmed state is even, then determining the current state of the memory to be the quiet state.