Communication method and communication system

• US 9,489,830 B2
• Filed: 06/05/2012
• Issued: 11/08/2016
• Est. Priority Date: 06/08/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ohshima, Kazuaki, Kobayashi, Hidetomo
• Primary Examiner(s): Mehmood, Jennifer
• Assistant Examiner(s): Mahase, Pameshanand
• Application Number:
  US13/488,873
• Publication Number:
  US 20120313762A1
• Time in Patent Office: 1,617 Days
• US Class Current: 1/1
• CPC Class Codes: G06K 7/10158 methods and means used by the interrogation device for reliably powering the wireless record carriers using an electromagnetic interrogation field
• CPC Class Codes: G06K 7/10366 the interrogation device being adapted for miscellaneous applications
• CPC Class Codes: G08C 17/00 Arrangements for transmitting signals characterised by the use of a wireless electrical link

Abstract

A command sequence is restarted from the middle even when supply of power supply voltage to an internal circuit in a wireless tag is temporarily stopped (a power flicker occurs). A register or a cache memory included in a signal processing circuit in the wireless tag continues to retain data even after the supply of power supply voltage is stopped. After the power flicker occurs, the signal processing circuit in the wireless tag is returned to the state before the supply of power supply voltage is stopped and can restart signal processing. Consequently, the command sequence can be restarted from the middle.

Claims

1. A communication method using a semiconductor device having a wireless function,

the communication method comprising the step of:

restarting a command sequence from a middle of the command sequence when supply of a power supply voltage is temporarily stopped,

wherein the command sequence comprises the step of;

holding data in a storage circuit,

wherein the storage circuit includes a transistor and a capacitor whose one of a pair of electrodes is electrically connected to a holding node that is set in a floating state when the transistor is turned off, and

wherein the storage circuit is electrically connected to a flip-flop so that a potential of a node in which the data in the flip-flop is retained is input to the holding node through the transistor.

2. The communication method according to claim 1, wherein the middle of the command sequence is a state before the supply of the power supply voltage is contemporarily stopped.

3. The communication method according to claim 1, the command sequence further comprising the step of:

repeating the step of holding data more than once.

4. The communication method according to claim 1,

wherein when the supply of the power supply voltage to a signal processing circuit is stopped, a ground potential is input to a gate of the transistor.

5. The communication method according to claim 1, wherein an oxide semiconductor layer comprises at least one element of indium and gallium.

6. The communication method according to claim 1, wherein the semiconductor device is a passive wireless tag.

7. A communication method using a semiconductor device having a wireless function, wherein the semiconductor device comprises a signal processing circuit including a flip-flop and a storage circuit,

the communication method comprising the step of:

restarting a command sequence from a middle of the command sequence when supply of a power supply voltage is temporarily stopped,

wherein the command sequence comprises the steps of;

receiving a command by the semiconductor device;

performing a signal processing on the basis of the command in the signal processing circuit;

holding data in the storage circuit, wherein the data is retained in the flip-flop; and

transmitting a response from the semiconductor device by modulating a first electromagnetic wave, wherein the response is based on a result of the signal processing,

wherein the storage circuit includes a transistor and a capacitor whose one of a pair of electrodes is electrically connected to a holding node that is set in a floating state when the transistor is turned off, and

wherein the storage circuit is electrically connected to the flip-flop so that a potential of a node in which the data in the flip-flop is retained is input to the holding node through the transistor.

8. The communication method according to claim 7, wherein a plurality of flip-flops functions as a register or a cache memory.

9. The communication method according to claim 7, wherein the middle of the command sequence is a state before the supply of the power supply voltage is contemporarily stopped.

10. The communication method according to claim 7, the command sequence further comprising the step of:

repeating the step of restarting the command sequence more than once.

11. The communication method according to claim 7, the command sequence further comprising the steps of:

transmitting the command from a reader/writer by modulating a second electromagnetic wave; and

receiving the response by the reader/writer.

12. The communication method according to claim 7,

wherein when the supply of the power supply voltage to the signal processing circuit is stopped, a ground potential is input to a gate of the transistor.

13. The communication method according to claim 7, wherein the transistor comprises an oxide semiconductor layer including at least one element of indium and gallium.

14. The communication method according to claim 7, the communication method further comprising the steps of:

inputting the first electromagnetic wave to a demodulation circuit;

demodulating the first electromagnetic wave in the demodulation circuit so as to obtain the command;

inputting the command to an encoder/decoder circuit after demodulating the first electromagnetic wave;

decoding the command in the encoder/decoder circuit;

inputting the command to the signal processing circuit through a bus after decoding the command;

inputting the response to the encoder/decoder circuit through the bus after performing the signal processing;

coding the response in the encoder/decoder circuit;

inputting the response to a modulation circuit after coding the response; and

modulating the response in the modulation circuit.

15. The communication method according to claim 7, wherein the semiconductor device is a passive wireless tag.

16. A communication method using a semiconductor device having a wireless function, wherein the semiconductor device comprises a signal processing circuit including a flip-flop and a storage circuit,

a command sequence comprising the step of:

holding data in the storage circuit,

the communication method comprising the steps of;

restarting to generate a power supply voltage so that the command sequence restarts from a middle of the command sequence when the command sequence is temporarily stopped,

inputting data retained in the storage circuit to the flip-flop;

performing signal processing in the signal processing circuit by using the data;

transmitting a response based on a result of the signal processing to a reader/writer by modulation of a electromagnetic wave in the semiconductor device;

receiving the response by the reader/writer; and

transmitting a command based on the response by modulation of the electromagnetic wave in the reader/writer,

wherein the storage circuit includes a transistor and a capacitor whose one of a pair of electrodes is electrically connected to a holding node that is set in a floating state when the transistor is turned off, and

wherein the storage circuit is electrically connected to the flip-flop so that a potential of a node in which the data in the flip-flop is retained is input to the holding node through the transistor.

17. The communication method according to claim 16, wherein the flip-flop functions as a register or a cache memory.

18. The communication method according to claim 16, wherein the middle of the command sequence is a state before supply of the power supply voltage is contemporarily stopped.

19. The communication method according to claim 16, the command sequence further comprising the step of:

repeating the step of holding data more than once.

20. The communication method according to claim 16,

wherein when supply of the power supply voltage to the signal processing circuit is stopped, a ground potential is input to a gate of the transistor.

21. The communication method according to claim 16, wherein the semiconductor device comprises an oxide semiconductor layer including at least one element of indium and gallium.

22. The communication method according to claim 16, the communication method further comprising the steps of:

inputting a first electromagnetic wave to a demodulation circuit;

demodulating the first electromagnetic wave in the demodulation circuit so as to obtain the command;

inputting the command to an encoder/decoder circuit after demodulating the first electromagnetic wave;

decoding the command in the encoder/decoder circuit;

inputting the command to the signal processing circuit through a bus after decoding the command;

inputting the response to the encoder/decoder circuit through the bus after performing the signal processing;

coding the response in the encoder/decoder circuit;

inputting the response to a modulation circuit after coding the response; and

modulating the response in the modulation circuit.

23. The communication method according to claim 16, wherein the semiconductor device is a passive wireless tag.

24. A communication system comprising:

a semiconductor device for performing wireless communication,

wherein the semiconductor device includes a signal processing circuit for performing signal processing on the basis of a command,

wherein the signal processing circuit includes a register,

wherein the register includes plural sets of a flip-flop and a storage circuit for storing data retained in the flip-flop,

wherein the storage circuit includes a transistor and a capacitor whose one of a pair of electrodes is electrically connected to a holding node that is set in a floating state when the transistor is turned off, and

wherein the storage circuit is electrically connected to the flip-flop so that a potential of a node in which the data in the flip-flop is retained is input to the holding node through the transistor.

25. The communication system according to claim 24,

wherein when supply of power supply voltage to the signal processing circuit is stopped, a ground potential is input to a gate of the transistor.

26. The communication system according to claim 24, wherein the semiconductor device is a passive wireless tag.

27. The communication system according to claim 24, the communication system further comprising a reader/writer,

wherein the semiconductor device receives the command from the reader/writer.

28. The communication system according to claim 24, wherein the transistor comprises an oxide semiconductor layer including at least one element of indium and gallium.