RFID access method using an indirect memory pointer
View Patent ↗A method of operating a memory in an RFID application includes locating a memory pointer at a fixed read/writeable memory location in the memory, determining a range of a pedigree buffer, initializing the memory pointer to a lowest value in the range, providing a second memory location that serves as a trigger address for an indirect write, and writing to a next location in the pedigree buffer by directing write data to the trigger address, which is then automatically written at a location pointed to by the memory pointer.
1. A method of writing to a memory, the method comprising:
maintaining a memory pointer at a fixed read/writeable memory location in the memory; and
responsive to receiving a write command in a single wireless/RFID operation recognizing a trigger address contained in the write command as an instruction for an indirect write, writing the data to the memory locations starting at an address stored in the memory pointer and incrementing, when the writing is complete, the address stored in the memory pointer to be an address of a location in the memory to which further data may be written,
wherein incrementing includes determining a range of memory locations in which data may be written, and storing in the memory pointer a lowest address of the range of memory locations.
2. The method of claim 1 further comprising allowing the address stored in the memory pointer to automatically wrap back to the original lowest address of the range of locations.
3. The method of claim 1 further comprising locking data that is in locations with addresses below the address in the memory pointer so that the locations cannot be overwritten by another operation, including a direct write to the memory.
4. The method of claim 1 performed on a FRAM memory.
5. The method of claim 1 wherein the memory is resident on an RFID tag.
6. The method of claim 1 performed in conjunction with a controller.
7. A memory circuit comprising:
a state machine;
a memory; and
pointer circuitry coupled between the state machine and the memory;
wherein the memory has a fixed read/writeable location at which is located a memory pointer; and
wherein the state machine and pointer circuitry are operable to responsive to receiving a write command in a single wireless/RFID operation write data to the memory starting at an address stored in the memory pointer upon recognizing a trigger address in a write command, and operable to increment the address stored in the memory pointer when the data write is complete to a next available location in the memory to which further data may be written,
wherein incrementing includes determining a range of memory locations in which data may be written, and storing in the memory pointer a lowest address of the range of memory locations.
8. The memory circuit of claim 7 wherein the state machine comprises a Gen 2 EPC (Generation 2 Electronic Product Code) state machine for providing the increment, load, address, and pointer control signals.
9. The memory circuit of claim 8 wherein the pointer circuitry comprises an incrementer for receiving the increment control signal.
10. The memory circuit of claim 8 wherein the pointer circuitry comprises an address pointer register for receiving the load control signal.
11. The memory circuit of claim 8 wherein the pointer circuitry comprises a multiplexer for receiving the pointer control signal.
12. The memory circuit of claim 7 wherein the pointer circuitry comprises: an incrementer; an address pointer register coupled to the incrementer; a multiplexer coupled to the state machine, the address pointer register, and the memory.
13. The circuit of claim 7 wherein the circuit is resident on an RFID tag.
14. The circuit of claim 7 wherein in the state machine is capable of performing a single or a multiple memory read or write operation.
15. The circuit of claim 7 wherein the memory comprises FRAM memory.
16. An RFID system comprising:
an RFID tag configured to communicate using wireless transmissions with an RFID reader; wherein
the RFID tag comprises a memory including a fixed read/writeable memory location in which the RFID tag stores a memory pointer;
the RFID tag is configured to determine a range of memory locations in which data may be written and to store in the memory pointer a lowest address of the range of memory locations; and
the RFID tag is configured to responsive to receiving write command a write command from the RFID reader in a single wireless/RFID operation and in response to the write command recognize a trigger address in the write command as an instruction to perform an indirect write operation by which data is written to the memory starting at the address in the memory pointer, and increment, at the completion of the indirect write operation, the address stored in the memory pointer to be the lowest address of a memory location to which further data may be written,
wherein incrementing includes determining a range of memory locations in which data may be written, and storing in the memory pointer a lowest address of the range of memory locations.
17. The RFID system of claim 16 , wherein the RFID tag comprises a FRAM memory.
18. The RFID system of claim 16 , wherein the RFID tag further comprises a state machine and pointer circuitry, wherein the pointer circuitry is coupled between the state machine and the memory.
19. The RFID system of claim 18 wherein the pointer circuitry comprises: an incrementer; an address pointer register coupled to the incrementer; a multiplexer coupled to the state machine, the address pointer register, and the memory.