CN215729844U

CN215729844U - Smart card communication circuit

Info

Publication number: CN215729844U
Application number: CN202122259306.7U
Authority: CN
Inventors: 后东超; 方誉; 丁发根
Original assignee: Hangzhou Vango Technologies Inc
Current assignee: Hangzhou Vango Technologies Inc
Priority date: 2021-09-17
Filing date: 2021-09-17
Publication date: 2022-02-01
Anticipated expiration: 2031-09-17

Abstract

The utility model discloses a smart card communication circuit, which aims at the problem that a 7816 interface is required to be arranged on a main control chip when a smart card is used at present. There is provided a smart card communication circuit comprising: the optical coupler comprises a Schmidt reverse-phase trigger, a first optical coupler and a second optical coupler; the first end of the input end of the first optical coupler is connected with a first power supply, the second end of the input end of the first optical coupler is connected with a TXD end, the first end of the output end of the first optical coupler is grounded, and the second end of the output end of the first optical coupler is connected with the input end and the output end of the intelligent card interface; the first end of the input end of the second optocoupler is connected with a second power supply, the second end of the input end of the second optocoupler is connected with the first path of output end of the Schmidt reverse-phase trigger, the first path of input end of the second optocoupler is connected with the second path of output end of the second optocoupler, the second end of the second optocoupler is connected with the input end and the output end of the intelligent card interface, and the first end of the output end of the second optocoupler is grounded, and the second end of the second optocoupler is connected with the RXD end. Therefore, the input and output ends of the intelligent card interface can be directly connected to the TXD end and the RXD end of the MCU, the 7816 interface is not needed by the main control chip, and the selection range is greatly increased.

Description

Smart card communication circuit

Technical Field

The utility model relates to the field of smart card communication, in particular to a smart card communication circuit.

Background

Along with the development of the times, the use of small and exquisite light smart card is more and more common, wherein, 7816 agreement is adopted usually in the transmission of data between smart card interface and the main control chip, and use this agreement and need 7816 hardware interface, in addition, in the in-process of actual use, can meet the application that needs keep apart the smart card, in smart card circuit one side, use 7816 conversion chip to convert the two-way input/output of single line of smart card interface into an unidirectional input and an unidirectional output usually, after the isolation, this unidirectional input and unidirectional output are connected on the specific 7816 interface that has independent input and independent output of main control chip, use the hardware mode to realize 7816 communication, main control chip selection range reduces, and the limitation is big, difficult popularization.

Therefore, those skilled in the art need a smart card communication circuit to solve the problems of large limitation and difficult popularization of the currently used communication circuit.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a smart card communication circuit, which solves the problems that the currently used communication circuit has large limitation and is difficult to popularize.

To solve the above technical problem, the present invention provides a smart card communication circuit, including: the optical coupler comprises a Schmidt reverse-phase trigger, a first optical coupler and a second optical coupler;

the first end of the input end of the first optical coupler is connected with a first power supply, the second end of the input end of the first optical coupler is connected with a data transmitting end (TXD) end of a Micro Control Unit (MCU), the first end of the output end of the first optical coupler is grounded, and the second end of the output end of the first optical coupler is connected with the input end and the output end of the intelligent card interface;

the first end of the input end of the second optical coupler is connected with a second power supply, the second end of the input end of the second optical coupler is connected with the first path output end of the Schmidt reverse-phase trigger, the first path input end of the Schmidt reverse-phase trigger is connected with the second path output end of the Schmidt reverse-phase trigger, the second path input end of the Schmidt reverse-phase trigger is connected with the input/output end of the intelligent card interface, the first end of the output end of the second optical coupler is grounded, and the second end of the output end of the second optical coupler is connected with the RXD end of the MCU.

Preferably, the input terminal of the second power supply is connected to the third power supply, and the control circuit is disposed between the third power supply and the power supply terminal of the smart card interface and used for controlling the second power supply to be powered on.

Preferably, the control circuit for controlling the second power supply to be powered includes: the first resistor, the first capacitor and the first triode;

the first end of the first resistor is connected with the first output end of the MCU and the base electrode of the first triode, the second end of the first resistor is connected with the third power supply and the emitting electrode of the first triode, the collecting electrode of the first triode is connected with the first end of the first capacitor, the second power supply and the power supply end of the intelligent card interface respectively, and the second end of the first capacitor is grounded.

Preferably, the method further comprises the following steps: a third optocoupler;

the first end of the input end of the third optical coupler is connected with a third power supply, the second end of the input end of the third optical coupler is connected with the detection end of the intelligent card interface, the first end of the output end of the third optical coupler is grounded, and the second end of the output end of the third optical coupler is connected with the input end of the MCU.

Preferably, the method further comprises the following steps: a fourth optical coupler;

the first end of the input end of the fourth optical coupler is connected with the first power supply, the second end of the input end of the fourth optical coupler is connected with the second output end of the MCU, the first end of the output end of the fourth optical coupler is grounded, and the second end of the output end of the fourth optical coupler is connected with the reset end of the intelligent card interface.

Preferably, the method further comprises the following steps: a fifth optocoupler;

the first end of the input end of the fifth optical coupler is connected with the first power supply, the second end of the input end of the fifth optical coupler is connected with the first output end of the MCU, the first end of the output end of the fifth optical coupler is grounded, and the second end of the output end of the fifth optical coupler is connected with a control circuit used for controlling the second power supply to be powered on.

Preferably, the signal processing circuit is used for processing signal waveforms and accelerating the transmission speed of signals, and the signal processing circuit is respectively arranged between the input end of the first optical coupler and the input and output end of the intelligent card interface and between the input end of the second optical coupler and the TXD end.

Preferably, the signal arrangement circuit arranged between the input terminal of the first optical coupler and the input/output terminal of the smart card interface includes: the second resistor, the third resistor, the fourth resistor, the second capacitor and the second triode;

the first end of second resistance is connected with the second end and the second power of the output of first opto-coupler, the second end of second resistance is connected with the collecting electrode of second triode and the input/output end of smart card interface, the first end of third resistance and the first end of the output of first opto-coupler, the first end of second electric capacity and the first end of fourth resistance are connected, the second end of third resistance and the second end of second electric capacity and the base of second triode are connected, the second end of fourth resistance is connected and ground connection with the projecting pole of second triode.

Preferably, the signal arrangement circuit disposed between the input terminal of the second optical coupler and the TXD terminal includes: the third resistor, the sixth resistor, the seventh resistor, the third capacitor and the third triode;

the first end of a fifth resistor is connected with a collector of the third triode and a receiving data (RXD) end of the MCU, the second end of the fifth resistor is connected with the second end of the output end of the second optocoupler and the first power supply, the first end of a sixth resistor is connected with the base of the third triode and the first end of the third capacitor, the second end of the sixth resistor is respectively connected with the first end of the output end of the second optocoupler, the second end of the third capacitor and the first end of the seventh resistor, and the second end of the seventh resistor is connected with an emitter of the third triode and grounded.

Preferably, the third power supply is a normally powered power supply.

According to the intelligent card communication circuit, when the TXD end of the MCU outputs a low level, the first optocoupler is conducted, and the input end and the output end of the intelligent card interface input the low level; when the TXD end of the MCU outputs a high level, the first optocoupler is cut off, and the input end and the output end of the intelligent card interface input the high level; when the input and output ends of the smart card interface output low levels, the second optocoupler is conducted, and the RXD end of the MCU inputs the low levels; when the input and output ends of the smart card interface output high levels, the second optocoupler is cut off, and the RXD end of the MCU inputs the high levels; like this, just divide into two circuits of special input and special output with the one-way two-way input/output of smart card interface, simultaneously, owing to need not to use 7816 conversion chip, the input that obtains and output also need not special 7816 interface, can connect on MCU's TXD end and RXD end, and the main control chip need not to have special 7816 interface, and selection range greatly increased has improved smart card communication circuit's suitability.

Drawings

In order to illustrate the embodiments of the present invention more clearly, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained by those skilled in the art without inventive effort.

FIG. 1 is a block diagram of a smart card communication circuit provided by the present invention;

fig. 2 is a block diagram of another smart card communication circuit provided by the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative work belong to the protection scope of the present invention.

The core of the utility model is to provide a smart card communication circuit.

In order that those skilled in the art will better understand the disclosure, the utility model will be described in further detail with reference to the accompanying drawings and specific embodiments.

In the application of smart card, often need use the 7816 interface when carrying out data transmission, its input/output end is the two-way interface of a single line, in the application that needs the smart card to keep apart, often utilize 7816 conversion chip to change an input/output into two data ports that are used for input and output respectively, then keep apart through the opto-coupler, the input and the output of the specific 7816 interface of use of being connected to the main control chip, this main control chip who just requires to use with the smart card cooperation will have the 7816 interface, thus, just received certain restriction when carrying out main control chip's selection, the restriction that the smart card used has been increased.

To this end, as shown in fig. 1, the present application provides a smart card communication circuit comprising: a Schmitt reverse trigger U6, a first optical coupler U1 and a second optical coupler U2;

the first end of the input end of the first optical coupler U1 is connected with a first power supply VDD, the second end of the input end of the first optical coupler U1 is connected with a TXD end of the MCU, the first end of the output end of the first optical coupler U1 is grounded, and the second end of the output end of the first optical coupler U1 is connected with the input end and the output end of the smart card interface;

the first end of the input end of the second optical coupler U2 is connected with a second power supply V _ CARD, the second end of the input end of the second optical coupler U2 is connected with the output end of a first U6A of a Schmidt reverse-phase trigger U6, the input end of a first U6A of the Schmidt reverse-phase trigger U6 is connected with the output end of a second U6B of the Schmidt reverse-phase trigger U6, the input end of a second U6B of the Schmidt reverse-phase trigger U6 is connected with the input and output end of the intelligent CARD interface, the first end of the output end of the second optical coupler is grounded, and the second end of the output end of the second optical coupler is connected with the RXD end of the MCU.

When the TXD end of the MCU outputs a low level, the first optocoupler U1 is switched on, the input/output end of the smart card interface is input with the low level, when the TXD end of the MCU outputs a high level, the first optocoupler U1 is switched off, the input/output end of the smart card interface is input with the high level, and a data transmission circuit for transmitting data from the TXD end of the MCU to the input/output end of the smart card interface in a one-way manner is formed;

when the input and output ends of the smart card interface output low levels, the second optical coupler U2 is switched on, the RXD end of the MCU is input with low levels, and when the input and output ends of the smart card interface output high levels, the second optical coupler U2 is switched off, the RXD end of the MCU is input with high levels, so that a data transmission circuit which transmits data from the input and output ends of the smart card interface to the RXD end of the MCU in a single direction is formed;

therefore, the input/output port of a single-wire bidirectional smart card interface is divided into two paths to be connected with the TXD end and the RXD end of the MCU, and the two paths are respectively specially used for transmitting data and specially used for receiving data.

It will be readily appreciated that the present embodiment is not intended to limit the smartcard communications circuit to the one mentioned above. In fact, in the actual using process, devices such as a current limiting resistor or a pull-up resistor can be added at the port, and since this needs to be set correspondingly according to the actual situation and is easily understood by those skilled in the art, this embodiment is not described herein again.

It should be noted that, the embodiment does not limit the specific voltage of the first power supply VDD and whether the first power supply VDD is a normal power supply, but one preferred scheme is as follows: the first power supply VDD is a normal power supply of 5V. In addition, although the schmitt inverting flip-flop U6 mentioned in this embodiment is an integrated 6-way schmitt flip-flop, this embodiment uses only two ways, but it is easy to know that the schmitt inverting flip-flop U6 is not necessarily a 6-way schmitt inverting flip-flop, and two independent schmitt inverting flip-flops may also implement the same function, this embodiment is only a preferred scheme of selecting an integrated device in consideration of space saving when the schmitt inverting flip-flop U6 is also used in other parts of the circuit. For example, in a clock circuit, a schmitt inverting flip-flop U6 is also used: two ends of the crystal oscillator are grounded through two capacitors respectively and are connected with a resistor in parallel, the first end of the crystal oscillator is connected with the input end of one Schmidt reverse-phase trigger U6, the other end of the crystal oscillator is connected with the output end of one Schmidt reverse-phase trigger U6 and the input end of the other Schmidt reverse-phase trigger U6 respectively, and the output end of the other Schmidt reverse-phase trigger U6 is connected with a clock signal (CLK) end of the intelligent card interface.

This embodiment utilizes the opto-coupler to realize converting the two-way input/output end of smart card interface single line to two line connection that input respectively and output and serve at MCU's TXD end and RXD, has saved 7816 conversion chip, and so, the circuit after the conversion is not needing the 7816 interface, and corresponding master control chip also need not to possess the 7816 interface, has increased the scope that master control chip selected, has reduced local limitation, is favorable to smart card communication circuit's popularization.

Since the smart card is not always inserted into the smart card interface, if the power of each circuit is always kept on, the power is not a little wasted, and the service life of the smart card power source in single charging is also reduced, as shown in fig. 2, in order to solve this problem, the present embodiment includes, on the basis of the above embodiment: the input end of the second Power supply V _ CARD is connected with a third Power supply VCC, and the control circuit is arranged between the third Power supply VCC and the Power supply end Power of the smart CARD interface and used for controlling the second Power supply V _ CARD to be electrified.

It should be noted that, the above embodiment does not limit whether the third power source VCC is a power source for supplying power in a normal state, and a specific voltage value, but a preferred scheme is that the third power source VCC is a 5V power source for supplying power in a normal state, and it can be known from the above embodiment that the second power source V _ CARD is a power source for supplying power to the smart CARD interface, so whether to power up the smart CARD interface can be controlled by controlling whether to power up the second power source V _ CARD. The third power source VCC is used for supplying power to the second power source V _ CARD, and the second power source V _ CARD control circuit controls whether the second power source V _ CARD and the third power source VCC are conducted or not.

It is easy to understand that the specific form of the control circuit is not limited in this embodiment, and the second power supply V _ CARD may be powered on when the MCU detects that the smart CARD is inserted into the smart CARD interface, powered off when the MCU detects that the smart CARD is not inserted into the smart CARD interface, or powered on manually by pressing a key switch or the like when the user needs to perform smart CARD identification.

But one preferred way is: the control circuit for controlling the second power supply V _ CARD to be powered on comprises: the circuit comprises a first resistor R1, a first capacitor C1 and a first triode Q1; the first end of the first resistor R1 is connected with the first output end Power _ Ctl of the MCU and the base of the first triode Q1, the second end of the first resistor R1 is connected with the third Power VCC and the emitter of the first triode Q1, the collector of the first triode Q1 is connected with the first end of the first capacitor C1, the second Power V _ CARD and the Power supply end Power of the intelligent CARD interface respectively, and the second end of the first capacitor C1 is grounded.

When the MCU detects that the smart CARD is inserted into the interface, the first output end Power _ Ctl of the MCU outputs low level, the first triode Q1 is conducted, the second Power supply V _ CARD is electrified, and the smart CARD can be operated at the moment; when the MCU does not detect that the smart CARD is inserted into the interface, the first output end Power _ Ctl of the MCU outputs high level, the first triode Q1 is cut off, the second Power supply V _ CARD is powered off, and the smart CARD cannot be operated at the moment.

It is easy to understand that the judgment basis for the MCU to detect whether the smart CARD is inserted is the signal sent by the detection terminal CARD _ IN of the smart CARD interface, so the power supply for supplying power to the detection terminal CARD _ IN of the smart CARD interface should be other power supplies different from the second power supply V _ CARD, otherwise the MCU will not detect that the smart CARD is inserted, and the second power supply V _ CARD will power down, and the power down of the second power supply V _ CARD will power down the detection terminal CARD _ IN of the smart CARD interface, and will not detect whether the smart CARD is inserted, and will not realize the function. However, the present embodiment does not limit the power supply for supplying power to the detection terminal CARD _ IN of the smart CARD interface, and a suitable power supply is selected according to actual needs, and one preferred scheme is as follows: and the power supply for supplying power to the detection terminal CARD _ IN of the smart CARD interface is a third power supply VCC.

The advantages of this embodiment over the above embodiments are: the second power supply V _ CARD control circuit is used for supplying power to the smart CARD interface when the smart CARD is inserted so as to operate the smart CARD, and when no smart CARD is inserted, the smart CARD does not need to be operated, and the second power supply V _ CARD is powered down at the moment so as to save electric energy, avoid meaningless waste and increase the service time of single charging of a power supply of the smart CARD system.

In practical applications of the smart card, since the smart card interface generates many transient pulses when operating the smart card, if the main control chip is directly connected to the smart card interface, these pulses will have a small impact on the chip, and in order to solve such problems, as shown in fig. 2, this embodiment provides a preferred solution based on the above-mentioned embodiments:

the smart card communication circuit disclosed in the present application further comprises: a third optical coupler U3; the first end of the input end of the third opto-coupler U3 is connected with a third power VCC, the second end of the input end of the third opto-coupler U3 is connected with the detection end CARD _ IN of the smart CARD interface, the first end of the output end of the third opto-coupler U3 is grounded, and the second end of the output end of the third opto-coupler U3 is connected with the input State of the MCU.

The third optical coupler U3 is used for photoelectric isolation of a detection end CARD _ IN of the smart CARD interface, when a smart CARD is inserted, the detection end CARD _ IN of the smart CARD interface outputs a low level, the third optical coupler U3 is conducted, the input end State of the MCU obtains the low level, and the smart CARD is judged to be inserted; when no smart CARD is inserted, the detection end CARD _ IN of the smart CARD interface outputs high level, the third optocoupler U3 is cut off, the input end State of the MCU obtains high level, and it is judged that no smart CARD is inserted.

As shown in fig. 2, the smart card communication circuit disclosed in the present application further includes: a fourth optical coupler U4; the first end of the input end of the fourth optical coupler U4 is connected with a first power supply VDD, the second end of the input end of the fourth optical coupler U4 is connected with a second output end Reset of the MCU, the first end of the output end of the fourth optical coupler U4 is grounded, and the second end of the output end of the fourth optical coupler U4 is connected with a Reset end CARD _ RST of the smart CARD interface.

The fourth optical coupler U4 is used for photoelectric isolation of the Reset terminal CARD _ RST of the smart CARD interface, when the second output end Reset of the MCU outputs a low level, the fourth optical coupler U4 is conducted, the Reset terminal CARD _ RST of the smart CARD interface obtains a low level, and the smart CARD is Reset; when the second output end Reset of the MCU outputs a non-low level, the fourth optical coupler U4 is cut off, and the resetting of the smart card is finished.

The advantages of this embodiment over the above embodiments are: the photoelectric isolation circuit is arranged between the MCU and the smart card interface, so that the transient pulse generated at the smart card interface can not influence the MCU, and the communication stability of the smart card is enhanced.

As can be seen from the foregoing embodiment, the Power supply terminal Power of the smart CARD interface and the MCU also have circuit connections, so that isolation is also required, and in order to ensure that the second Power supply V _ CARD control circuit can implement functions, as shown in fig. 2, this embodiment further includes, on the basis of the foregoing embodiment: a fifth optocoupler U5; the first end of the input end of the fifth optical coupler U5 is connected with a first Power supply VDD, the second end of the input end of the fifth optical coupler U5 is connected with a first output end Power _ Ctl of the MCU, the first end of the output end of the fifth optical coupler U5 is grounded, and the second end of the output end of the fifth optical coupler U5 is connected with a control circuit used for controlling the second Power supply V _ CARD to be powered on.

The fifth optical coupler U5 is used for isolating the Power supply end Power of the smart CARD interface from the first output end Power _ Ctl of the MCU, when the first output end Power _ Ctl of the MCU outputs a low level, the fifth optical coupler U5 is conducted, the first triode Q1 is conducted, the second Power supply V _ CARD is powered on, and the Power supply end Power of the smart CARD interface is powered on; when the first output end Power _ Ctl of the MCU outputs a non-low level, the fifth optocoupler U5 is cut off, the first triode Q1 is cut off, the second Power supply V _ CARD is powered off, and the Power supply end Power of the smart CARD interface is powered off, so that the smart CARD cannot be operated.

The advantages of this embodiment over the above embodiments are: set up photoelectric isolation circuit between MCU and smart card interface's Power end Power and make the transient pulse that smart card interface department produced can not influence MCU, further strengthened the stability of smart card communication.

In the in-service use, because the optical coupling keeps apart the limitation on communication rate, for making the signal more stable easy discernment, can set up filter circuit or other circuit that have the effect of arrangement waveform between the input/output end of smart card interface and MCU, so, as shown in fig. 2, this embodiment is on the basis of above-mentioned embodiment, still including the signal arrangement circuit who is used for arranging signal waveform in order and accelerates the transmission speed of signal, signal arrangement circuit sets up respectively between the input of first opto-coupler U1 and the input/output end of smart card interface and between the input of second opto-coupler U2 and TXD end.

Wherein the signal arrangement circuit who sets up between the input of first opto-coupler U1 and the input/output end of smart card interface includes: the circuit comprises a second resistor R2, a third resistor R3, a fourth resistor R4, a second capacitor C2 and a second triode Q2; the first end of a second resistor R2 is connected with the second end of the output end of a first optical coupler U1 and a second power supply V _ CARD, the second end of a second resistor R2 is connected with the collector of a second triode Q2 and the input/output end of a smart CARD interface, the first end of a third resistor R3 is connected with the first end of the output end of a first optical coupler U1, the first end of a second capacitor C2 and the first end of a fourth resistor R4, the second end of the third resistor R3 is connected with the second end of a second capacitor C2 and the base of the second triode Q2, and the second end of the fourth resistor R4 is connected with the emitter of the second triode Q2 and grounded.

The signal arrangement circuit that sets up between the input of second opto-coupler U2 and TXD end includes: a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3 and a third triode Q3; the first end of a fifth resistor R5 is connected with the collector of the third triode Q3 and the RXD end of the MCU, the second end of the fifth resistor R5 is connected with the second end of the output end of the second optocoupler U2 and the first power supply VDD, the first end of a sixth resistor R6 is connected with the base of the third triode Q3 and the first end of a third capacitor C3, the second end of the sixth resistor R6 is connected with the first end of the output end of the second optocoupler U2, the second end of the third capacitor C3 and the first end of a seventh resistor R7, and the second end of the seventh resistor R7 is connected with the emitter of the third triode Q3 and grounded.

The advantages of this embodiment over the above embodiments are: the signal arranging circuit is added between the input end and the output end of the MCU and the intelligent card interface, so that the waveform can be arranged, the signal is not easy to distort, the transmission speed of the signal can be accelerated, and the communication stability of the intelligent card is further enhanced.

According to the embodiment, the ports of the interface part of the smart card do not need to be powered in real time, and the power consumption can be reduced by powering down the ports when the ports are not needed to be used. However, IN order to ensure the timeliness of the detection of the smart CARD, the detection terminal CARD _ IN of the smart CARD interface needs to be kept IN the power-on state all the time, so this embodiment provides an optimal solution as follows: the third power VCC is a power supply for supplying power in a normal state.

It should be noted that this embodiment is only a preferred embodiment, and no limitation is made on the voltage value and the power type of the third power source VCC, and an appropriate voltage value and power type should be selected according to the needs of practical applications.

The advantages of this embodiment are: the third power VCC for supplying power to the detection terminal CARD _ IN of the smart CARD interface is a power supply for supplying power IN a normal state, so that the detection terminal CARD _ IN of the smart CARD interface is IN a power-on state all the time, and the detection timeliness is ensured.

The smart card communication circuit provided by the present invention is described in detail above. The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Claims

1. A smart card communication circuit, comprising: the optical coupler comprises a Schmidt reverse-phase trigger, a first optical coupler and a second optical coupler;

the first end of the input end of the first optical coupler is connected with a first power supply, the second end of the input end of the first optical coupler is connected with the TXD end of the MCU, the first end of the output end of the first optical coupler is grounded, and the second end of the output end of the first optical coupler is connected with the input end and the output end of the intelligent card interface;

the first end of the input end of the second optical coupler is connected with a second power supply, the second end of the input end of the second optical coupler is connected with the output end of the first path of the Schmidt reverse-phase trigger, the input end of the first path of the Schmidt reverse-phase trigger is connected with the output end of the second path of the Schmidt reverse-phase trigger, the input end of the second path of the Schmidt reverse-phase trigger is connected with the input and output end of the intelligent card interface, the first end of the output end of the second optical coupler is grounded, and the second end of the output end of the second optical coupler is connected with the RXD end of the MCU.

2. The smart card communication circuit of claim 1, wherein the input terminal of the second power supply is connected to a third power supply, and further comprising a control circuit disposed between the third power supply and the power supply terminal of the smart card interface for controlling the second power supply to be powered on.

3. The smart card communication circuit of claim 2, wherein the control circuit for controlling the second power supply to power up comprises: the first resistor, the first capacitor and the first triode;

the first end of the first resistor is connected with the first output end of the MCU and the base of the first triode, the second end of the first resistor is connected with the third power supply and the emitting electrode of the first triode, the collecting electrode of the first triode is respectively connected with the first end of the first capacitor, the second power supply and the power supply end of the intelligent card interface, and the second end of the first capacitor is grounded.

4. The smart card communication circuit of claim 3, further comprising: a third optocoupler;

the first end of the input end of the third optical coupler is connected with the third power supply, the second end of the input end of the third optical coupler is connected with the detection end of the intelligent card interface, the first end of the output end of the third optical coupler is grounded, and the second end of the output end of the third optical coupler is connected with the input end of the MCU.

5. The smart card communication circuit of claim 1, further comprising: a fourth optical coupler;

the first end of the input end of the fourth optocoupler is connected with the first power supply, the second end of the input end of the fourth optocoupler is connected with the second output end of the MCU, the first end of the output end of the fourth optocoupler is grounded, and the second end of the output end of the fourth optocoupler is connected with the reset end of the intelligent card interface.

6. The smart card communication circuit of claim 3, further comprising: a fifth optocoupler;

the first end of the input end of the fifth optical coupler is connected with the first power supply, the second end of the input end of the fifth optical coupler is connected with the first output end of the MCU, the first end of the output end of the fifth optical coupler is grounded, and the second end of the output end of the fifth optical coupler is connected with the control circuit for controlling the second power supply to be powered on.

7. The smart card communication circuit according to claim 1, further comprising a signal arranging circuit for arranging signal waveforms and increasing transmission speed of signals, wherein the signal arranging circuit is respectively disposed between the input end of the first optical coupler and the input/output end of the smart card interface and between the input end of the second optical coupler and the TXD terminal.

8. The smart card communication circuit according to claim 7, wherein the signal arrangement circuit disposed between the input terminal of the first optical coupler and the input/output terminal of the smart card interface comprises: the second resistor, the third resistor, the fourth resistor, the second capacitor and the second triode;

the first end of second resistance with the second end of the output of first opto-coupler with the second power is connected, the second end of second resistance with the collecting electrode of second triode with the input-output end of smart card interface is connected, the first end of third resistance with the first end of the output of first opto-coupler the first end of second electric capacity with the first end of fourth resistance is connected, the second end of third resistance with the second end of second electric capacity with the base of second triode is connected, the second end of fourth resistance with the projecting pole of second triode is connected and ground connection.

9. The smart card communication circuit of claim 7, wherein the signal conditioning circuit disposed between the input terminal of the second optocoupler and the TXD terminal comprises: the third resistor, the sixth resistor, the seventh resistor, the third capacitor and the third triode;

the first end of the fifth resistor is connected with the collector electrode of the third triode and the RXD end of the MCU, the second end of the fifth resistor is connected with the second end of the output end of the second optocoupler and the first power supply, the first end of the sixth resistor is connected with the base electrode of the third triode and the first end of the third capacitor, the second end of the sixth resistor is connected with the first end of the output end of the second optocoupler, the second end of the third capacitor and the first end of the seventh resistor respectively, and the second end of the seventh resistor is connected with the emitter electrode of the third triode and grounded.

10. The smart card communication circuit according to any one of claims 2 to 4, wherein the third power supply is a normally powered power supply.