CN102255638B - Interface circuit meeting single wire protocol (SWP) on contactless front (CLF) chip of near field communication (NFC) controller - Google Patents
Interface circuit meeting single wire protocol (SWP) on contactless front (CLF) chip of near field communication (NFC) controller Download PDFInfo
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- CN102255638B CN102255638B CN201010180123.XA CN201010180123A CN102255638B CN 102255638 B CN102255638 B CN 102255638B CN 201010180123 A CN201010180123 A CN 201010180123A CN 102255638 B CN102255638 B CN 102255638B
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Abstract
The invention discloses an interface circuit meeting a single wire protocol (SWP) on a contactless front (CLF) chip of a near field communication (NFC) controller. The interface circuit comprises a resistor R1, an in-phase driver, a comparator and an inverter, wherein the resistor R1 is connected between a single wire protocol input/output (SWIO) signal wire and a power supply Vcc; the in-phase driver has an open collector; the input end of the in-phase driver is connected with an SWP processor, and the output end of the in-phase driver is connected with the SWIO signal wire; the positive input end of the comparator is connected with the SWIO signal wire, and the reverse input end of the comparator is connected with a comparison threshold level; output signals of the comparator are transmitted into the input of the inverter; and the input of the inverter is connected with the output of the comparator, and the output of the inverter is connected with the SWP processor. The interface circuit can accurately transmit the signal S1 to an NFC subscriber identity module (SIM) chip and accurately receive the signal S2 returned by the NFC SIM chip, thereby realizing full-duplex communication.
Description
Technical field
The present invention relates to wireless communication technology field, particularly relate to a kind of interface circuit that can realize communicating between NFC controller CLF chip with NFC SIM card chip in NFC system.
Background technology
In NFC (near field communication near-field communication) system, and NFC controller (also referred to as CLF---contactless front non-contact front-end) to be connected with SIM (subscriber identification module) the core of the card sheet.In the SIM card of routine, C1 (Vcc), C2 (RST), C3 (CLK), C5 (GND), C7 (IO) five pins are conventional SIM pins, meet the integrated circuit card specification of ISO7816 contact-carrying; C4 (RFU), C8 (RFU) pin are then expanded to USB high-speed interface by International Standards Organization; C6 (SWP) pin is used for connecting SIM card chip and NFC controller chip.Connection scheme mainly SWP (Single Wire Protocol, the single-wire-protocol) agreement of NFC controller chip and SIM card chip.
SWP agreement is the single line connection scheme based on SIM card C6 pin that Gemalto company proposes.As shown in Figure 2, in SWP agreement, the connection interface of SIM card chip and NFC controller chip comprises three connecting line: Vcc (C1 pin), GND (C5 pin), SWP (C6 pin), wherein SWP holding wire realizes full duplex communication based on voltage and load-modulate principle.
As shown in Figure 3,4, SWP agreement be between SIM card and NFC controller towards position, PPP(Point to Point Protocol).The principle of single-wire-protocol is based on the transmission of digital information under full-duplex mode, there is defined the signal of S1 and S2 both direction:
Signal S1 low or high by digital modulation in voltage domain (L or H) transmits;
Signal S2 low or high by digital modulation in current field (L or H) transmits.
When the state of the S1 signal of NFC controller CLF (main equipment) is high (H), SIM card (from equipment) also can be drawn high electric current (H state) or not draw high electric current (L state), carrys out signal transmission S2.Can transmit clock signal in the basis of coding of signal S1, when signal S1 is high state (H state), signal S2 is just effective, as shown in Figure 5.
Summary of the invention
The technical problem to be solved in the present invention is to provide the interface circuit a kind of NFC controller CLF chip meeting SWP agreement, the signal S1 meeting SWP agreement to the transmission of NFC SIM chip that can be correct, the signal S2 meeting SWP agreement that correct reception NFC SIM chip returns, realizes full duplex communication.
For solving the problems of the technologies described above, interface circuit NFC controller CLF chip of the present invention meeting SWP agreement comprises:
Be connected to the resistance R1 between SWIO holding wire and power Vcc;
One open-collector driven in phase device, its input is connected with SWP protocol processor, and output is connected with SWIO holding wire;
One comparator, its positive input connects SWIO holding wire, and reverse input end connects comparison threshold level, and its output signal sends into the input of inverter;
One inverter, its input is connected with the output of described comparator, and its output connects described SWP protocol processor;
When full duplex communication, by arranging the threshold level of comparator, NFC controller CLF chip correctly can receive the S2 signal that NFC SIM card chip returns;
The setting of described threshold level should meet following condition: threshold level is lower than the level of the current signal S2 meeting SWP agreement effectively and for meeting the voltage signal S1 of SWP agreement time low; Threshold level is higher than the level of the current signal S2 meeting SWP agreement effectively and for meeting the voltage signal S1 of SWP agreement time high.
The present invention gives on a NFC controller CLF and send voltage signal S1, the interface circuit of received current signal S2, this interface circuit structure is simple, and debugging is convenient; By this interface circuit, during full duplex communication, what NFC controller CLF can be correct sends to NFC SIM chip voltage signal S1, the current signal S2 that correct reception NFC SIM chip returns.
Accompanying drawing explanation
Below in conjunction with accompanying drawing and embodiment, the present invention is further detailed explanation:
Fig. 1 is interface circuit structure figure of the present invention;
Fig. 2 is based on SWIO single line connection scheme schematic diagram;
Fig. 3 is signal transmission definition schematic diagram in SWP scheme;
Fig. 4 is the equivalent circuit diagram of SWP signaling interface in SWP scheme;
Fig. 5 is the coding schematic diagram of SWP signal in SWP scheme.
Embodiment
Shown in Figure 1, interface circuit NFC controller CLF chip of the present invention meeting SWP agreement comprises: be connected to the resistance R1 between SWIO holding wire and power Vcc anode; One open-collector driven in phase device U3, its input is connected with SWP protocol processor, and output is connected with SWIO holding wire; One comparator U1, its positive input connects SWIO holding wire, and reverse input end connects comparison threshold level, and its output signal sends into the input of inverter U2; One inverter U2, the output of its input termination comparator, it exports termination SWP protocol processor.The present invention can be correct send to NFC SIM signal S1, the signal S2 that correct reception NFC SIM returns, thus realize full duplex communication.
When NFC controller CLF send meet coding rule signal to SIM card time, this output signal by driver U3 shaping in the same way strengthen drive after become signal S1 and deliver on SWIO holding wire.Now S1 signal also meets coding rule.If now SIM card wants inverse signal to NFC controller CLF, then SIM card reaches the object of Signal transmissions by the current signal S2 on control SWIO holding wire.
SIM card is flow to from NFC controller CLF according to SWP agreement electric current; When signal S2 is " H (height) ", the size of electric current is between 600 μ A-1200 μ A, and when signal is " L (low) ", the size of electric current is between 0-20 μ A.According to the coding rule of signal, only when signal S1 is high level, current signal S2 is just effective, when current signal S2 effectively and be height (600 ~ 1200 μ A electric current) time, electric current on SWIO line to flow through through resistance R1 from Vcc and causes the high level of signal S1 SWIO line to reduce, by comparator U1, current signal S2 is converted into voltage signal, oppositely gives SWP protocol processor through inverter U2.Thus realize full duplex communication.Because the electric current that resistance R1 flows through is smaller, the amplitude that signal S1 high level reduces can not be large, so the voltage of comparator U1 threshold level must be suitable.The setting of described threshold level should meet following condition: threshold level is lower than the level of the current signal S2 meeting SWP agreement effectively and for meeting the voltage signal S1 of SWP agreement time low; Threshold level is higher than the level of the current signal S2 meeting SWP agreement effectively and for meeting the voltage signal S1 of SWP agreement time high.
Above by embodiment to invention has been detailed description, but these are not construed as limiting the invention.Without departing from the principles of the present invention, those skilled in the art also can make many distortion and improvement, and these also should be considered as protection scope of the present invention.
Claims (2)
1. NFC controller CLF chip meets an interface circuit for SWP agreement, it is characterized in that, comprising:
Be connected to the resistance R1 between SWIO holding wire and power Vcc;
One open-collector driven in phase device, its input is connected with SWP protocol processor, and output is connected with SWIO holding wire;
One comparator, its positive input connects SWIO holding wire, and reverse input end connects comparison threshold level, and its output signal sends into the input of inverter;
One inverter, its input is connected with the output of described comparator, and its output connects described SWP protocol processor;
When full duplex communication, by arranging the threshold level of comparator, NFC controller CLF chip correctly can receive the S2 signal that NFC SIM card chip returns;
The setting of described threshold level should meet following condition: threshold level is lower than the level of the current signal S2 meeting SWP agreement effectively and for meeting the voltage signal S1 of SWP agreement time low; Threshold level is higher than the level of the current signal S2 meeting SWP agreement effectively and for meeting the voltage signal S 1 of SWP agreement time high.
2. interface circuit as claimed in claim 1, it is characterized in that: when NFC SIM card chip return current signal S2 is to NFC controller CLF, current signal is converted into voltage signal, so that the process of SWP protocol processor by resistance R1 and described comparator and inverter.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010180123.XA CN102255638B (en) | 2010-05-20 | 2010-05-20 | Interface circuit meeting single wire protocol (SWP) on contactless front (CLF) chip of near field communication (NFC) controller |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201010180123.XA CN102255638B (en) | 2010-05-20 | 2010-05-20 | Interface circuit meeting single wire protocol (SWP) on contactless front (CLF) chip of near field communication (NFC) controller |
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| CN102255638A CN102255638A (en) | 2011-11-23 |
| CN102255638B true CN102255638B (en) | 2015-04-22 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103886121B (en) * | 2012-12-24 | 2016-12-28 | 北京中电华大电子设计有限责任公司 | A kind of circuit realizing SWP agreement on SIM emulator |
| CN115174431B (en) * | 2022-06-30 | 2023-09-05 | 无锡融卡科技有限公司 | Simple SWP full duplex logic signal acquisition device and method |
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| CN101136078A (en) * | 2007-10-25 | 2008-03-05 | 上海复旦微电子股份有限公司 | Circuit of SIM card connecting non-contact front-end chip to realize mobile non-contact |
| CN101236453A (en) * | 2008-01-30 | 2008-08-06 | 上海华虹集成电路有限责任公司 | Connection structure and communicating method between NFC control chip and SIM card chip |
| CN101582759A (en) * | 2008-04-08 | 2009-11-18 | 意法半导体(胡希)公司 | Detection of data received by a master device in a single-wire communication protocol |
| CN101661548A (en) * | 2008-08-28 | 2010-03-03 | 中国科学院声学研究所 | Communication method for CLF chip and SIM card |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010114877A (en) * | 2008-10-06 | 2010-05-20 | Panasonic Corp | Operational amplifier circuit and display unit |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101136078A (en) * | 2007-10-25 | 2008-03-05 | 上海复旦微电子股份有限公司 | Circuit of SIM card connecting non-contact front-end chip to realize mobile non-contact |
| CN101236453A (en) * | 2008-01-30 | 2008-08-06 | 上海华虹集成电路有限责任公司 | Connection structure and communicating method between NFC control chip and SIM card chip |
| CN101582759A (en) * | 2008-04-08 | 2009-11-18 | 意法半导体(胡希)公司 | Detection of data received by a master device in a single-wire communication protocol |
| CN101661548A (en) * | 2008-08-28 | 2010-03-03 | 中国科学院声学研究所 | Communication method for CLF chip and SIM card |
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