ACS ACR122U User manual

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Application Programming Interface V2.02
ACR122U
USB NFC Reader

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Table of Contents
1.0. Introduction .............................................................................................................4
1.1. Features.................................................................................................................................4
1.2. USB Interface ........................................................................................................................5
2.0. Implementation........................................................................................................6
2.1. Communication Flow Chart of ACR122U ..............................................................................6
2.2. Smart Card Reader Interface Overview ................................................................................7
3.0. PICC Interface Description .....................................................................................8
3.1. ATR Generation.....................................................................................................................8
3.1.1. ATR format for ISO 14443 Part 3 PICCs ......................................................................8
3.1.2. ATR format for ISO 14443 Part 4 PICCs ......................................................................9
4.0. PICC Commands for General Purposes ..............................................................11
4.1. Get Data...............................................................................................................................11
5.0. PICC Commands (T=CL Emulation) for Mifare Classic Memory Cards .............12
5.1. Load Authentication Keys ....................................................................................................12
5.2. Authentication ......................................................................................................................13
5.3. Read Binary Blocks .............................................................................................................16
5.4. Update Binary Blocks ..........................................................................................................17
5.5. Value Block Related Commands .........................................................................................18
5.5.1. Value Block Operation ................................................................................................18
5.5.2. Read Value Block........................................................................................................19
5.5.3. Restore Value Block....................................................................................................20
6.0. Pseudo-APDUs ......................................................................................................21
6.1. Direct Transmit ....................................................................................................................21
6.2. Bi-Color LED and Buzzer Control........................................................................................22
6.3. Get the Firmware Version of the Reader.............................................................................24
6.4. Get the PICC Operating Parameter.....................................................................................25
6.5. Set the PICC Operating Parameter .....................................................................................26
6.6. Set Timeout Parameter........................................................................................................27
6.7. Set Buzzer Output Enable for Card Detection.....................................................................28
7.0. Basic Program Flow for Contactless Applications .............................................29
7.1. How to Access PC/SC-compliant Tags (ISO 14443-4)? .....................................................30
7.2. How to Access DESFire Tags (ISO 14443-4)? ...................................................................31
7.3. How to Access FeliCa Tags (ISO 18092)?..........................................................................32
7.4. How to Access NFC Forum Type 1 Tags (ISO 18092), e.g. Jewel and Topaz Tags?........33
7.5. Getting the Current Setting of the Contactless Interface.....................................................35
Appendix A. ACR122U PC/SC Escape Command ........................................................36
Appendix B. APDU Command and Response Flow for ISO 14443-Compliant Tags.. 39
Appendix C. APDU Command and Response Flow for ISO 18092-Compliant Tags.. 40
Appendix D. Error Codes ...............................................................................................41
Appendix E. Sample Codes for Setting the LED ..........................................................43
List of Figures
Figure 1 : Communication Flow Chart of ACR122U .............................................................................. 6
Figure 2 : Smart Card Reader Interface on the Device Manager .......................................................... 7

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Figure 3 : Basic Program Flow for Contactless Applications ............................................................... 29
Figure 4 : Topaz Memory Map ............................................................................................................. 34
List of Tables
Table 1 : USB Interface .......................................................................................................................... 5
Table 2 : ATR format for ISO 14443 Part 3 PICCs................................................................................. 8
Table 3 : ATR format for ISO 14443 Part 4 PICCs................................................................................. 9
Table 4 : Mifare 1k Memory Map .......................................................................................................... 14
Table 5 : Mifare 4K Memory Map ......................................................................................................... 14
Table 6 : Mifare Ultralight Memory Map ............................................................................................... 15
Table 7 : Bi-Color LED and Buzzer Control Format (1 Byte)................................................................ 22
Table 8 : Current LED State (1 Byte).................................................................................................... 23
Table 9 : PICC Operating Parameter. (Default Value = FFh)............................................................... 26

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1.0.Introduction
The ACR122U is a PC-linked contactless smart card reader/writer used for accessing ISO 14443-4
Type A and Type B, Mifare, ISO 18092 or NFC, and FeliCa tags. The ACR122U is PC/SC compliant
so it is compatible with existing PC/SC applications. Furthermore, the standard Microsoft CCID driver
is used to simplify driver installation.
The ACR122U serves as the intermediary device between the personal computer and the contactless
tag via the USB interface. The reader carries out the command from the PC whether the command is
used in order to communicate with a contactless tag, or control the device peripherals (LED or
buzzer).
The ACR122U uses the PC/SC APDUs for contactless tags following the PC/SC Specification and
makes use of pseudo APDUs in sending commands for ISO 18092 tags and controlling the device
peripherals. This document will discuss the ACR122U can be used in your smart card system.
1.1. Features
•USB 2.0 Full Speed Interface
•CCID Compliance
•Smart Card Reader:
oRead/Write speed of up to 424 kbps
oBuilt-in antenna for contactless tag access, with card reading distance of up to 50 mm
(depending on tag type)
oSupport for ISO 14443 Part 4 Type A and B cards, Mifare, FeliCa, and all four types of
NFC (ISO/IEC 18092 tags)
oBuilt-in anti-collision feature (only one tag is accessed at any time)
•Application Programming Interface:
oSupports PC/SC
oSupports CT-API (through wrapper on top of PC/SC)
•Built-in Peripherals:
oUser-controllable bi-color LED
oUser-controllable buzzer
•Supports Android™ OS 3.1 and above
•Compliant with the following standards:
oISO 14443
oCE
oFCC
oKC
oVCCI
oPC/SC
oCCID
oMicrosoft WHQL
oRoHS

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1.2. USB Interface
The ACR122U is connected to a computer through USB as specified in the USB Specification 1.1.
The ACR122U is working in full-speed mode, i.e. 12 Mbps.
Pin Signal Function
1 VBUS +5 V power supply for the reader (Max. 200 mA, Normal 100 mA)
2 D- Differential signal transmits data between ACR122U and PC
3 D+ Differential signal transmits data between ACR122U and PC
4 GND Reference voltage level for power supply
Table 1: USB Interface

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2.0.Implementation
2.1. Communication Flow Chart of ACR122U
The Standard Microsoft CCID and PC/SC drivers are used; thus, no ACS drivers are required
because the drivers are already built inside the windows operating system. Your computer’s registry
settings can also be modified to be able to use the full capabilities of the ACR122U NFC Reader. See
Appendix A for more details.
Figure 1: Communication Flow Chart of ACR122U

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2.2. Smart Card Reader Interface Overview
Click on the “Device Manager” to find out the “ACR122U PICC Interface.” The standard Microsoft
USB CCID Driver is used.
Figure 2: Smart Card Reader Interface on the Device Manager

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3.0.PICC Interface Description
3.1. ATR Generation
If the reader detects a PICC, an ATR will be sent to the PC/SC driver for identifying the PICC.
3.1.1. ATR format for ISO 14443 Part 3 PICCs
Byte Value
(Hex) Designation Description
0 3Bh Initial Header -
1 8Nh T0
Higher nibble 8 means: no TA1, TB1, TC1
only TD1 is following.
Lower nibble N is the number of historical
bytes (HistByte 0 to HistByte N-1)
2 80h TD1
Higher nibble 8 means: no TA2, TB2, TC2
only TD2 is following.
Lower nibble 0 means T = 0
3 01h TD2
Higher nibble 0 means no TA3, TB3, TC3,
TD3 following.
Lower nibble 1 means T = 1
4
To
3+N
80h T1
Category indicator byte, 80 means A status
indicator may be present in an optional
COMPACT-TLV data object
4Fh
Tk
Application identifier Presence Indicator
0Ch Length
RID Registered Application Provider Identifier
(RID) # A0 00 00 03 06h
SS Byte for standard
C0 .. C1h Bytes for card name
00 00 00 00h RFU RFU # 00 00 00 00h
4+N UUh TCK Exclusive-oring of all the bytes T0 to Tk
Table 2: ATR format for ISO 14443 Part 3 PICCs
Example:
ATR for Mifare 1K = {3B 8F 80 01 80 4F 0C A0 00 00 03 06 03 00 01 00 00 00 00 6Ah}
ATR
Initial
Header T0 TD1 TD2 T1 Tk Length RID Standard Card Name RFU TCK
3Bh 8Fh 80h 01h 80h 4Fh 0Ch
A0 00
00 03
06h
03h 00 01h 00 00
00 00h 6Ah
Where:
Length (YY) = 0Ch

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RID = A0 00 00 03 06h(PC/SC Workgroup)
Standard (SS) = 03h (ISO 14443A, Part 3)
Card Name (C0 .. C1) = [00 01h] (Mifare 1K)
Where, Card Name (C0 .. C1)
00 01h: Mifare 1K
00 02h: Mifare 4K
00 03h: Mifare Ultralight
00 26h: Mifare Mini
F0 04h: Topaz and Jewel
F0 11h: FeliCa 212K
F0 12h: Felica 424K
FFh [SAK]: Undefined
3.1.2. ATR format for ISO 14443 Part 4 PICCs
Byte Value (Hex) Designation Description
0 3Bh Initial Header -
1 8Nh T0
Higher nibble 8 means: no TA1, TB1, TC1
only TD1 is following.
Lower nibble N is the number of historical
bytes (HistByte 0 to HistByte N-1)
2 80h TD1
Higher nibble 8 means: no TA2, TB2, TC2
only TD2 is following.
Lower nibble 0 means T = 0
3 01h TD2
Higher nibble 0 means no TA3, TB3, TC3,
TD3 following.
Lower nibble 1 means T = 1
4
to
3 + N
XXh T1 Historical Bytes:
ISO 14443A:
The historical bytes from ATS response. Refer
to the ISO14443-4 specification.
ISO 14443B:
The higher layer response from the ATTRIB
response (ATQB). Refer to the ISO14443-3
specification.
XXh
XX
XXh
Tk
4+N UUh TCK Exclusive-oring of all the bytes T0 to Tk
Table 3: ATR format for ISO 14443 Part 4 PICCs
We take for example, an ATR for DESFire, which is:
DESFire (ATR) = 3B 86 80 01 06 75 77 81 02 80 00h

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ATR
Initial Header T0 TD1 TD2 ATS
T1 Tk TCK
3Bh 86h 80h 01h 06h 75 77 81 02 80h 00h
This ATR has 6 bytes of ATS, which is: [06 75 77 81 02 80h]
Note: Use the APDU “FF CA 01 00 00h” to distinguish the ISO 14443A-4 and ISO 14443B-4 PICCs,
and retrieve the full ATS if available. The ATS is returned for ISO14443A-3 or ISO14443B-3/4 PICCs.
Another example would be the ATR for ST19XRC8E, which is:
ST19XRC8E (ATR) = 3B 8C 80 01 50 12 23 45 56 12 53 54 4E 33 81 C3 55h
ATR
Initial Header T0 TD1 TD2 ATQB
T1 Tk TCK
3Bh 86h 80h 01h 50h 12 23 45 56 12 53 54 4E 33 81 C3h 55h
Since this card follows ISO 14443 Type B, the response would be ATQB which is 50 12 23 45 56 12
53 54 4E 33 81 C3h is 12 bytes long with no CRC-B
Note: You can refer to the ISO7816, ISO14443 and PC/SC standards for more details.