CN113988094A

CN113988094A - Contactless transponder and method

Info

Publication number: CN113988094A
Application number: CN202110846444.7A
Authority: CN
Inventors: J-L·拉拜雷
Original assignee: STMicroelectronics Grenoble 2 SAS
Current assignee: STMicroelectronics Grenoble 2 SAS
Priority date: 2020-07-27
Filing date: 2021-07-26
Publication date: 2022-01-28

Abstract

Embodiments of the present disclosure relate to contactless transponders and methods. According to one aspect, a contactless transponder comprises: a memory; an antenna configured to receive a signal; a contactless interface coupled to the antenna and configured to issue a memory access request in accordance with the received signal; a wired interface configured to receive a memory access request; an arbitration module configured to grant access to the memory for access requests issued by the contactless interface or for access requests received by the wired interface, and wherein the wired interface is further configured to receive and send power-off controls to the arbitration module, the arbitration module being configured to be able to turn off the contactless interface upon receipt of the power-off controls.

Description

Contactless transponder and method

Cross Reference to Related Applications

The present application claims the benefit of french application No. 2007916 filed on 27/7/2020, which is hereby incorporated by reference.

Technical Field

Embodiments and implementations of the present disclosure relate to contactless transponders, in particular to NFC transponders or RFID transponders.

Background

Radio frequency identification is well known in the field of wireless (contactless) communication technology, more commonly known by the name RFID (radio frequency identification). RFID may use radio frequency waves to automatically detect and identify transponders attached to objects.

Near field communication is also well known in the art of wireless communication, and more commonly known by the name NFC (near field communication), which is an extension of radio frequency identification.

Near field communication enables short-range communication between the contactless reader and the transponder by means of radio frequency waves.

A contactless transponder is an electronic device that is capable of exchanging information with a contactless reader via an antenna according to a contactless communication protocol, such as a protocol compatible with NFC or RFID technology.

The contactless transponder may be a tag or a card.

Such a contactless transponder can be incorporated in a connecting object which also comprises a microcontroller. The contactless transponder is then used as a gateway between the contactless reader and the microcontroller of the connected object.

The connection object may be a connected watch, or a connected home automation device, or other connected public device (such as a connected street light), examples of which are not limiting.

The contactless reader is an external communication device, which may be, for example, a cellular mobile phone (also referred to as a "smartphone").

The contactless transponder may comprise a wired interface allowing communication with the microcontroller and a contactless interface connected to an antenna of the connected object allowing communication with the contactless reader.

The contactless transponder may further comprise a memory accessible by the wired interface and the contactless interface.

Such a contactless transponder acting as a gateway may also be referred to as a "dynamic transponder" because the data temporarily stored in its memory may change over time, either due to the contactless reader or due to the microcontroller.

For such transponders, simultaneous access to the memory via the wired interface and the contactless interface is not possible. Therefore, arbitration solutions are typically provided, allowing management of memory access. In particular, arbitration solutions used include handing memory access over to wired and contactless interfaces that first issue access requests. As long as the memory is accessed by the interface that obtains access, memory access requests of other interfaces are ignored.

The interface waiting for a memory access has no piece of information about the state of the memory access. Therefore, this interface will issue new access requests periodically until it is granted access to the memory.

However, access requests of the contactless interface may be frequent, especially when the transponder is attacked by repeated access requests issued by the contactless reader. In this case, the access request issued by the microcontroller can be ignored as long as the memory access is allocated to the contactless interface. Thus, access requests from the contactless interface make it difficult or even impossible for the microcontroller to access the memory. Thus, assigning memory access rights to a wired interface can be time and energy consuming, as the microcontroller must issue access requests on a regular basis.

Therefore, there is a need to provide a solution that allows the transponder to grant the microcontroller access to the memory at any time, in particular when the contactless interface issues repeated access requests.

Disclosure of Invention

According to one aspect, a contactless transponder comprises: a memory; an antenna configured to receive a signal (in particular a radio frequency signal); a contactless interface coupled to the antenna and configured to issue a memory access request in accordance with the received signal; a wired interface configured to receive a memory access request; an arbitration module configured to grant access to the memory for access requests issued by the contactless interface or for access requests received by the wired interface, and wherein the wired interface is further configured to receive and send power-off controls to the arbitration module, the arbitration module being configured to be able to turn off the contactless interface upon receipt of the power-off controls, so as to grant exclusive access to the memory for access requests received by the wired interface.

In particular, the wired interface may be configured to receive memory access requests from a master module external to the transponder, in particular via the bus. The master module is a processing unit, such as a microcontroller. The master module may be configured to issue a power down control and a responder access request to the memory.

Thus, the transponder can act as a gateway between the master module and the contactless reader.

The proposed transponder is configured to switch off the contactless interface as soon as the main module indicates that it wishes to access the memory by sending a power-off control to the wired interface of the transponder. By closing the contactless interface, the latter can no longer access the memory.

Therefore, the contactless interface can no longer prevent the master module from accessing the memory.

In this way, the master module gains exclusive access to the memory.

Such a transponder is therefore robust against attacks of repeated access requests issued by the contactless reader.

In an advantageous embodiment, the arbitration module is configured to generate an interrupt signal and to send the interrupt signal to the output of the transponder after closing the contactless interface.

Thus, the responder output is configured to send an interrupt signal to the master module. In particular, the main module may include an input electrically connected to the output of the transponder, the connection being through a wired connection to receive the interrupt signal. The interrupt signal then allows the master module to be informed that the contactless interface has been closed. Thus, the interrupt signal may indicate to the master that its memory access request may be processed.

Therefore, the master does not have to send memory access requests periodically until memory access is allowed. The master simply waits to receive an interrupt signal. Upon receiving the interrupt signal, the master is notified that its memory access request is to be granted.

The power consumption of the master module is reduced because the master module only has to wait for receiving the interrupt signal. Furthermore, time can be saved, since the interrupt signal indicates the moment at which the access request can be issued and granted.

In addition, the traffic on the bus is also reduced.

In an advantageous embodiment, the wired interface is further configured to receive reactivation controls and to send these reactivation controls to an arbitration module, which is configured to reactivate the contactless interface upon receipt of the reactivation controls.

In particular, the master module may be configured to issue reactivation controls that are sent to the wired interface.

Thus, the wired interface may be configured to receive reactivation control from the master module.

In this way, the master module is configured to reactivate the contactless interface when access to the memory is no longer required.

In particular, the master module may be configured to be able to reactivate the contactless interface at the end of a memory access by the master module.

Alternatively or in combination, the contactless interface may also be reactivated when the wired interface is deactivated (in particular when the wired power supply is switched off).

In an advantageous embodiment, the arbitration module is configured to receive a piece of information about the status of a write access of the contactless interface to the memory and to wait for the write access to complete to close the contactless interface when receiving a power-off control while the write access of the contactless interface to the memory is ongoing.

Thus, the transponder is configured to allow the contactless interface to complete writing to the memory upon receiving the power-off control.

The transponder then allows to protect memory corruption that may occur when the contactless interface is switched off before the writing is completed.

Advantageously, the wired interface is adapted to be coupled to I²C (inter integrated circuit) bus. Alternatively, the bus may be of the SPI (serial peripheral interface) type.

Preferably, the wired interface is configured to receive a control including an address and useful data.

Thus, the wired interface is adapted to interface with I²Type C bus communication.

In an advantageous embodiment, the shutdown control is a control comprising an address and a read/write bit dedicated to the shutdown control. Preferably, the address is represented by 7 bits.

Then, the shutdown control has a simple structure. This structure is suitable for the structural formula I²Type C bus transmission.

Because a dedicated address is selected for this power down control, the power down control is not treated as a memory access request by the responder. Thus, the shutdown control has no effect on the processing of memory access requests over the bus.

Advantageously, the shutdown control is represented by a single byte. The shutdown control can then be sent quickly.

Alternatively, however, shutdown control may be provided which may be represented on more than one byte.

Also, in an advantageous embodiment, the reactivation control is a control that includes only the address and read/write bits dedicated to the reactivation control.

Then, the reactivation control has a simple structure. This structure is suitable for the structural unit I²Type C bus transmission.

Specifically, the address for the reactivation control is different from the address for the shutdown control.

Since a specific address is selected for this reactivation control, the reactivation control is not treated as a memory access request by the responder. Thus, reactivation control has no effect on the handling of memory access requests over the bus.

In an advantageous embodiment, the reactivation control is represented by a single byte. The reactivation control can then be sent quickly.

Alternatively, however, a reactivation control may also be provided that may be represented by more than one byte.

Preferably, the transponder is capable of exchanging information items with an external contactless reader via the antenna according to a contactless communication protocol compatible with NFC or RFID technology.

According to another aspect, a system includes a transponder as described above, and a main module coupled to a wired interface of the transponder, the main module configured to issue a power-off control to the transponder, and then to send a memory access request after an arbitration module of the transponder turns off a contactless interface performed after receiving the power-off control of the wired interface.

In an advantageous embodiment, the master module is a microcontroller.

According to another aspect, a connection object is defined that comprises a system as described above.

According to another aspect, a method for managing access to a memory of a transponder as described above includes receiving, by a wired interface, a shutdown control, then sending the shutdown control to an arbitration module, and then closing, by the arbitration module, a contactless interface to grant exclusive access to the memory for an access request received by the wired interface.

In an advantageous embodiment, the method comprises generating an interrupt signal by the arbitration module after the contactless interface is closed by the arbitration module, and then sending the interrupt signal to the output of the transponder.

In an advantageous embodiment, the closing of the contactless interface is performed after completion of a write access to the memory by the contactless interface when a shutdown control is received while the write access is in progress.

In an advantageous embodiment, the method comprises, after closing the contactless interface, receiving a reactivation control over the wired interface, then sending the reactivation control to the arbitration module, and then reactivating the contactless interface by the arbitration module.

Drawings

Further advantages and characteristics of the invention will become apparent from a review of the detailed description of embodiments and examples (which are in no way limiting) and the accompanying drawings, in which:

FIG. 1 illustrates a system including a contactless transponder and a master module;

FIG. 2 illustrates a memory access management method;

3-7 illustrate timing diagrams of various memory access management examples; and

FIG. 8 illustrates a connected object including the system of FIG. 1.

Detailed Description

Fig. 1 schematically illustrates a system SYS according to an embodiment. The system SYS is configured to communicate with a contactless reader LSC.

The contactless reader LSC may be an external contactless communication device, such as a multifunctional mobile phone, a so-called "smartphone".

The contactless reader LSC comprises an antenna ANTL.

The system SYS comprises a contactless transponder TRS and a main module MM.

The main module MM is a processing unit, for example a microcontroller.

The transponder TRS may be a tag or a card.

The transponder TRS acts as a gateway between the master module MM and the contactless reader LSC.

The transponder TRS includes an antenna ANT configured to receive a radio frequency signal RAD emitted by the contactless reader LSC.

In particular, the transponder TRS is able to exchange information items with the contactless reader LSC via the antenna ANT according to a contactless communication protocol, for example compatible with NFC or RFID technology.

NFC technology is an open technology platform, standardized in the standards ISO/IEC 18092 and ISO/IEC21481, and incorporates many existing standards, such as ISO 14443 or ISO 15693 for communication protocols, for example.

When an information item is transmitted between the reader LSC and the transponder TRS, the reader LSC generates, through its antenna ANTL, a magnetic field, which is typically a sinusoidal carrier of 13.56 MHz. The information pieces are transmitted by amplitude modulation of the carrier.

The transponder TRS includes a contactless interface IR coupled to an antenna ANT.

The contactless interface IR comprises in particular a demodulator (not shown) adapted to demodulate the received radio frequency signals in order to obtain the data transmitted from the reader LSC.

The transponder TRS further includes a wired interface IF connected to the main module MM via bus BI. Preferably, bus BI is I²And C, a bus. Alternatively, bus BI may be of the SPI (serial peripheral interface) type, for example.

In particular, bus BI comprises two bidirectional lines. The first SDA line is configured to transmit data. The second SCL line is the synchronous clock line.

The contactless transponder TRS further comprises a memory MEM, in particular a non-volatile memory. The memory MEM may be an EEPROM memory, for example.

The contactless reader LSC is configured to issue an access request to the memory MEM for the transponder TRS. These access requests are transmitted to the transponder TRS by means of radio frequency signals RAD, which can be received by the antenna ANT of the transponder TRS.

The contactless interface IR is configured to receive MEM access requests generated by radio frequency signals from the contactless reader LSC received by the antenna ANT.

The contactless interface can be in an activated or deactivated state. The state of the contactless interface is memorized in a register.

The main module MM is also configured to issue a request to the memory MEM for access to the transponder LSC and to send this request to the wired interface IF via the bus BI.

Thus, the wired interface IF is configured to receive access requests to the memory MEM issued by the main module MM.

However, the memory MEM cannot be accessed by both access requests received by the wired interface IF and access requests received by the contactless interface IR.

The transponder TRS then includes an arbitration module MA allowing to manage access to the memory MEM.

The arbitration module MA may be a logic circuit.

The arbitration module MA is connected to the wired interface IF, the contactless interface IR and the memory MEM. Thus, the arbitration module MA can receive access requests from the wired interface IF and the contactless interface IR and then send these requests to the memory MEM.

In addition, main module MM is also configured to issue shutdown control and send the shutdown control to wired interface IF through bus BI.

The wired interface IF is configured to receive and send shutdown control to the arbitration module MA.

The arbitration module MA is configured to receive a power-off control from the wired interface IF and to switch off the contactless interface IR upon receiving such a power-off control.

Turning off the contactless interface IR may prevent the contactless reader LSC from accessing the memory MEM of the transponder TRS. The access request issued by the contactless reader LSC is ignored.

The master has exclusive access to the memory.

In particular, the transponder TRS is configured to switch off the contactless interface IR as soon as the main module MM indicates that it wishes to access the memory MEM by sending a power-off control to the wired interface IF of the transponder TRS. By turning off the contactless interface IR, the contactless interface IR can no longer access the memory MEM.

In this way, the master module MM gains exclusive access to the memory MEM.

Therefore, the contactless interface IR can no longer prevent the access of the master module MM to the memory MEM.

Thus, such a transponder TRS is powerful for attacks on repeated access requests from the contactless reader LSC.

More specifically, the arbitration module MM is configured to turn off the contactless interface IR after waiting for completion of a write access to the memory MEM by the contactless interface IR when it receives a power-off control while the write access is in progress by the contactless interface IR.

The arbitration module MA is therefore configured to prevent damage to the memory MEM that may occur when the contactless interface IR is switched off before the writing is completed.

Preferably, the shutdown control is a control including only an address and a read/write bit dedicated to the shutdown control.

Then, the shutdown control has a simple structure. This structure is suitable for the structural formula I²Type C bus BI.

Since a dedicated address is selected for this power-off control, the power-off control is not treated as a memory access request by the responder TRS. Therefore, the shutdown control has no influence on the processing of the memory access request through the bus BI.

Advantageously, the shutdown control is represented by a single byte, and the address dedicated to shutdown control is represented by 7 bits.

In this way, the shutdown control can be sent quickly.

Furthermore, the arbitration module MA is configured to generate an interrupt signal INT and to send it to the output O1 of the transponder TRS after closing the contactless interface IR after receiving the shutdown control.

The output O1 is then configured to send the interrupt signal INT to the input I1 of the main module MM through a wired connection between the output O1 and the input I1.

The interrupt signal INT may inform the master module MM that the contactless interface IR has been switched off. The interrupt signal INT can thus indicate to the master module MM that its access request to the memory MEM can be processed.

Therefore, the master module MM does not have to periodically send a request to access the memory MEM until the memory MEM access request is granted. The master module MM only has to wait for the reception of the interrupt signal INT to know that it can issue a request for access to the memory MEM after issuing the power-off control.

Since the main module MM only has to wait for receiving the interrupt signal INT, the power consumption of the main module MM is reduced. Furthermore, time can be saved, since the interrupt signal INT indicates the moment at which an access request can be issued and granted.

In addition, traffic on bus BI is reduced.

In addition, main module MM is also configured to issue reactivation control and send it to wired interface IF through bus BI.

The arbitration module is configured to receive reactivation control from the wired interface IF and to reactivate the contactless interface IR after receiving such reactivation control.

Reactivating the contactless interface IR allows the contactless reader LSC to re-access the memory MEM of the transponder TRS. Thus, the access request from the contactless interface IR is no longer ignored.

Preferably, the reactivation control is a control including only an address and a read/write bit dedicated to the reactivation control.

Then, the reactivation control has a simple structure. This structure is suitable for the structural unit I²Type C bus BI transmission.

Since a private address is selected for this reactivation control, the reactivation control is not seen by the responder TRS as a memory access request. Thus, reactivation control has no effect on the handling of memory access requests through bus BI.

Preferably, the reactivation control is represented by a single byte, and the address dedicated to reactivation control is represented by 7 bits.

The reactivation control can then be sent quickly.

Alternatively or in combination, the arbitration module may be configured to be able to reactivate the contactless interface when the wired interface is deactivated (in particular when the wired power supply is switched off).

Fig. 2 illustrates a memory access management method that can be implemented by the transponder TRS described above.

In step 20, the arbitration module MA receives the shutdown control from the main module MM received by the wired interface IF.

If the contactless interface IR is making write access to the memory MEM when the arbitration module MA receives the power-off control, the arbitration module MA waits for the write access to be completed in step 21 and then turns off the contactless interface IR in step 22.

Otherwise, if the contactless interface IR is not in the process of performing a write access to the memory MEM, the arbitration module MA proceeds directly to step 22 after receiving the shutdown control, thereby shutting down the contactless interface IR.

After turning off the contactless interface IR in step 22, the arbitration module MA generates an interrupt signal INT in step 23 and sends the interrupt signal INT to the wired interface IF. This interrupt signal is sent to the output O1 of the transponder TRS. This interrupt signal is then sent to the input I1 of the master module MM via the wired connection between the input I1 of the master module and the output O1 of the transponder TRS. This interrupt signal is used to indicate to the master module MM its exclusive access to the memory MEM.

The contactless interface IR remains switched off in step 24 until the arbitration module MA receives reactivation control from the main module MM received by the wired interface IF.

Upon receiving the reactivation control, the arbitration module reactivates the contactless interface in step 25.

Alternatively, the arbitration module may reactivate the contactless interface when the wired interface is deactivated (in particular when the wired power supply is switched off).

Fig. 3 to 7 illustrate examples of embodiments of the above memory access management method. In these figures, signal 100 represents the radio frequency control received and emitted by the contactless interface IR, signal 101 represents the shutdown control received by the wired interface IF, and signal 102 represents the write access status of the memory MEM by the contactless interface IR (a high state of the signal indicates that a write access is in progress and a low state indicates that no write access is present). Signal 103 represents the status of the contactless interface (a high state of the signal indicates that the contactless interface is activated and a low state indicates that the contactless interface is deactivated) and signal 104 represents an interrupt signal (shown as a low state).

In the example shown in fig. 3, the shutdown control CA is received by the arbitration module MA before the contactless reader LSC issues an access request RA to the memory.

The access request RA is sent in a frame comprising a first start frame bit S, the access request RA and a last end frame bit E. The power-off control CA is sent in a frame comprising a first start frame bit S, a power-off control CA, followed by an acknowledge bit a and an end frame bit P.

As indicated by the low state of signal 102, no write access is in progress at the end of receiving the shutdown control AC.

The arbitration module MA can directly switch off the contactless interface IR, since no write access to the memory is in progress. Signal 103 thus switches to a low state. After switching off the contactless interface IR, the arbitration module MA generates an interrupt signal and sends an interrupt signal to the wired interface IF (see signal 104 switching to low state).

With the contactless interface IR switched off, the access request of the contactless reader LSC is not processed. Therefore, no response is sent after the access request (no response is indicated by the information fragment NREP). The master module MM then gets exclusive access to the memory MEM by the transponder TRS.

In the example shown in fig. 4, the shutdown control CA is received by the arbitration module MA, while the access request RA issued by the contactless reader LSC is also received by the arbitration module MA.

As previously mentioned, the access request RA is sent in a frame comprising a first start frame bit S, the access request RA and a last end frame bit E; the power-off control CA is sent in a frame comprising a first start frame bit S, a power-off control CA, followed by an acknowledge bit a and an end frame bit P.

The reception of the power-off control ends before the reception of the access request ends. Thus, at the end of the reception of the shutdown control, no write access is in progress, as indicated by the low state of signal 102.

The arbitration module MA can directly switch off the contactless interface IR, since no write access to the memory is in progress. Thus, signal 103 switches to a low state.

After switching off the contactless interface IR, the arbitration module MA generates an interrupt signal and sends it to the wired interface IF (see signal 104 switching to low state).

With the contactless interface IR switched off, access requests issued by the contactless reader LSC are not processed. Therefore, no response is sent after the access request (no response is indicated by the slice NREP). The master module MM then obtains exclusive access to the memory MEM by the transponder TRS.

In the example shown in fig. 5, the arbitration module MA receives the power-off control CA after receiving the memory access request NWM from the contactless reader LSC but before the responder TRS issues a response to this access control. Here, the access request NWM is not a memory write access request.

The access request NWM is sent in a frame comprising a first start frame bit S and then the access request NWM ends in a last end frame bit E. The power-off control CA is sent in a frame comprising a start frame bit S, a power-off control CA, followed by an acknowledge bit a and an end frame bit P.

The arbitration module MA can directly switch off the contactless interface IR, since no write access to the memory is in progress. Signal 103 thus switches to a low state.

With the contactless interface IR switched off, access requests from the contactless reader LSC are not processed. After the access request, no response is sent (no response is indicated by the information NREP). The master module MM then gets exclusive access to the memory MEM by the transponder TRS.

In the example shown in fig. 6, the arbitration module MA receives the power-off control CA after receiving a write access request WM to the memory from the contactless reader LSC, but before the responder TRS issues a response to this access control.

The write access WM request is sent in a frame that includes a first start frame bit S, an access request WM, and then a last end frame bit E. The power down control CA is sent in a frame comprising a start frame bit S, the power down control CA, followed by an acknowledge bit a and an end frame bit P.

Since a write memory access is in progress, the arbitration module MA cannot directly turn off the contactless interface IR to prevent memory corruption that may result from turning off the contactless interface IR during a write access to the memory by the contactless interface IR.

The arbitration module MA therefore waits for the completion of the write access before closing the contactless interface IR. After the write access is completed, the arbitration module MA closes the contactless interface IR. Signal 103 thus switches to a low state.

With the contactless interface IR switched off, no response is sent after this access request (the lack of response is indicated by the information NREP). The master module MM then gets exclusive access to the memory MEM by the transponder TRS.

In the example shown in fig. 7, a contactless reader LSC issues a memory access request. The memory access request is processed and a response REP to the access request is sent to the contactless reader LSC.

The access request RA is sent in a frame comprising a first start frame bit S, the access request RA and then a last end frame bit E. The response REP is contained in the frame starting with the start frame bit S. The power-off control CA is sent in a frame comprising a start frame bit S, a power-off control CA, followed by an acknowledge bit a and an end frame bit P.

The shutdown control is received after the transmission of the response to the contactless reader LSC is started but before the end of the transmission. Since no write access to the memory occurs after receiving the shutdown control, the arbitration module MA can directly turn off the contactless interface IR. Signal 103 thus switches to a low state.

With the contactless interface IR switched off, the access request issued by the contactless reader LSC is not processed, nor is the sending of the response REP finalized. The master module MM then obtains exclusive access to the memory MEM by the transponder TRS.

The system SYS described above may be used in the field of connecting objects. Fig. 8 thus schematically illustrates a connection object OBJ comprising a system SYS as described above. The connection object OBJ may be a connected watch, or a connected home automation device, or a connected public device, such as a connected light pole, without limitation.

Claims

1. A contactless transponder comprising:

a memory;

an antenna configured to receive a signal;

a contactless interface coupled to the antenna and configured to issue a first memory access request in accordance with the received signal;

a wired interface configured to receive a second memory access request, receive a shutdown control, and send the shutdown control to an arbitration module; and

the arbitration module configured to:

authorizing access to the memory for the first memory access request issued by the contactless interface or for the second memory access request received by the wired interface; and

upon receiving a shutdown control, closing the contactless interface to grant exclusive access to the memory for the second memory access request received by the wired interface.

2. The contactless transponder of claim 1, wherein the arbitration module is configured to generate an interrupt signal and send the interrupt signal to an output of the contactless transponder after the contactless interface is closed.

3. The contactless transponder of claim 1, wherein the wired interface is further configured to receive a reactivation control and to send the reactivation control to the arbitration module, the arbitration module configured to reactivate the contactless interface when the arbitration module receives the reactivation control.

4. The contactless transponder of claim 1, wherein the arbitration module is configured to receive a piece of information regarding a status of write access of the contactless interface to the memory, and to wait for the write access to complete to turn off the contactless interface when the power-off control is received while the write access of the contactless interface to the memory is in progress.

5. The contactless transponder of claim 1, wherein the wired interface is configured to receive a control including an address and useful data, the shutdown control being a control including only an address and a read/write bit dedicated to the shutdown control.

6. The contactless transponder of claim 5, wherein the shutdown control is represented by a single byte.

7. A contactless transponder according to claim 3, wherein the wired interface is configured to receive a control including an address and useful data, the reactivation control being a control including only an address and a read/write bit dedicated to the reactivation control.

8. The contactless transponder of claim 7, wherein the reactivation control is represented by a single byte.

9. The contactless transponder of claim 1, wherein the wired interface is adapted to be coupled to I²And C, a bus.

10. Contactless transponder according to claim 1, capable of exchanging information items with an external contactless reader via the antenna according to a contactless communication protocol compatible with near field communication or radio frequency identification technology.

11. A system, comprising:

a contactless transponder comprising:

a memory;

an antenna configured to receive a signal;

the arbitration module configured to:

closing the contactless interface upon receiving a shutdown control from the main module to grant exclusive access to the memory for the second memory access request received by the wired interface; and

the primary module coupled to the wired interface of the contactless transponder, the primary module configured to

Receiving the shutdown control via the wired interface.

Sending the shutdown control to the contactless transponder; and

sending the second memory access request after shutdown of the contactless interface is performed by the arbitration module of the contactless transponder.

12. The system of claim 11, wherein the master module is a microcontroller.

13. The system of claim 11, wherein the arbitration module is configured to generate an interrupt signal and send the interrupt signal to an output of the contactless transponder after the contactless interface is closed.

14. The system of claim 11, wherein the wired interface is further configured to receive a reactivation control and to send the reactivation control to the arbitration module, the arbitration module configured to reactivate the contactless interface when the arbitration module receives reactivation control.

15. The system of claim 11, wherein the arbitration module is configured to receive a piece of information regarding a status of write access of the contactless interface to the memory, and to wait for the write access to complete to close the contactless interface when the shutdown control is received while the write access of the contactless interface to the memory is in progress.

16. The system of claim 11, wherein the wired interface is configured to receive a control including an address and useful data, the shutdown control being a control including only an address and read/write bits dedicated to the shutdown control.

17. A method for managing access to a memory of a transponder, the transponder comprising: an antenna configured to receive a signal; a contactless interface coupled to the antenna and configured to issue a first memory access request in accordance with the received signal; a wired interface configured to receive a second memory access request; and an arbitration module configured to grant access to the memory for the first memory access request issued by the contactless interface or for the second memory access request received by the wired interface, the method comprising:

receiving, by the wired interface, a shutdown control;

sending the shutdown control to the arbitration module; and

closing, by the arbitration module, the contactless interface to grant exclusive access to the memory for the second memory access request received by the wired interface.

18. The method of claim 17, further comprising, after closing the contactless interface by the arbitration module:

generating, by the arbitration module, an interrupt signal; and

sending the interrupt signal to an output of the transponder.

19. The method of claim 17, wherein the shutdown of the contactless interface is performed after the write access is completed when the shutdown control is received while the write access of the contactless interface to the memory is in progress.

20. The method of claim 17, further comprising, after closing the contactless interface:

a reactivation control is received via the wired interface.

Sending the reactivation control to the arbitration module; and

reactivating, by the arbitration module, the contactless interface.