TI TRF7960ARHBT

TRF7960A
SLOS732 – JUNE 2011
www.ti.com
MULTI-PROTOCOL FULLY INTEGRATED 13.56-MHz RFID READER/WRITER IC
Check for Samples: TRF7960A
1 Introduction
1.1
Features
123
• Completely Integrated Protocol Handling for
ISO15693, ISO18000-3, ISO14443A/B, NFC
Forum Device Types 1 to 4, and FeliCa
• Input Voltage Range: 2.7 VDC to 5.5 VDC
• Programmable Output Power:
+20 dBm (100 mW) or +23 dBm (200 mW)
• Programmable I/O Voltage Levels:
1.8 VDC to 5.5 VDC
• Programmable System Clock Frequency
Output (RF, RF/2, RF/4)
• Programmable Modulation Depth
1.2
•
•
•
•
•
•
• Dual Receiver Architecture With RSSI for
Elimination of "Read Holes" and Adjacent
Reader System/Ambient In-Band Noise
Detection
• Programmable Power Modes for Ultra-Low
Power System Design (Power Down <0.5 µA)
• Parallel or SPI Interface
• Integrated Voltage Regulator for
Microcontroller Supply
• Temperature Range: -40°C to +110°C
• 32-Pin QFN Package (5 mm x 5 mm) (RHB)
Applications
Secure Access Control
Product Authentication
Contactless Payment Systems
Passport Reader Systems
Medical Systems
Remote Sensor Applications
1.3
Description
The TRF7960A is an integrated analog front end and data-framing device for a 13.56-MHz RFID
reader/writer system. Built-in programming options make it suitable for a wide range of applications for
proximity and vicinity identification systems.
The reader is configured by selecting the desired protocol in the control registers. Direct access to all
control registers allows fine tuning of various reader parameters as needed.
Comprehensive documentation, reference designs, evaluation modules, and TI microcontrollers (based on
MSP430™ or ARM™ technology) source code are available.
The TRF7960A is a high-performance 13.56-MHz HF RFID reader IC comprising an integrated analog
front end (AFE) and a built-in data framing engine for ISO15693, ISO14443A/B, and FeliCa. It supports
data rates up to 848 kbps for ISO14443 with all framing and synchronization tasks on board (in ISO Mode,
default). The TRF7960A also supports NFC Forum Tag Types 1, 2, 3, and 4 operations (as reader/writer
only). This architecture enables the customer to build a complete and cost-effective yet high-performance
multiprotocol HF RFID/NFC reader/writer using a low-cost microcontroller (for example, an MSP430).
Other standards and even custom protocols can be implemented by using two of the Direct Modes the
device offers. These Direct Modes (0 and 1) allow the user to fully control the analog front end (AFE) and
also gain access to the raw subcarrier data or the unframed, but already ISO formatted data and the
associated (extracted) clock signal.
1
2
3
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
MSP430 is a trademark of Texas Instruments.
ARM is a trademark of ARM Limited.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2011, Texas Instruments Incorporated
TRF7960A
SLOS732 – JUNE 2011
www.ti.com
VDD _I/O
MUX
RX_IN1
RX_IN2
Phase and
Amplitude
Detector
RSSI
(AUX)
RSSI
(External)
Phase and
Amplitude
Detector
VDD_PA
TX_ OUT
Gain
Transmitter Analog
Front End
Gain
RSSI
(Main)
Filter,
AGC
Digitizer
ISO
Protocol
Handling
Decoder
Framing
Bit
Framing
Logic
I/O_0
State
Control
Logic
(Control
Registers,
Command
Logic)
I/O_1
ASK/ OOK
12-Byte
FIFO
I/O_5
I/O_7
SYS _CLK
DATA _CLK
VDD _A
BAND _GAP
VSS _A
VDD _RF
Voltage Supply Regulator Systems
(Supply Regulators, Reference Voltages)
OSC_IN
Level
Shifter
VIN
Digital Control
State Machine
MOD
OSC_ OUT
I/O_4
IRQ
EN
EN2
I/O_3
I/O_6
MCU
Interface
Serial
Conversion
CRC, Parity
VSS_PA
I/O_2
VSS _RF
VDD_X
VSS
Crystal Oscillator
Timing System
VSS _D
Figure 1-1. Block Diagram
The receiver system has a dual-input receiver architecture. The receivers also include various automatic
and manual gain control options. The received input bandwidth can be selected to cover a broad range of
input subcarrier signal options.
The received signal strength from transponders, ambient sources or internal levels is available via the
RSSI register. The receiver output is selectable among a digitized subcarrier signal and any of the
integrated subcarrier decoders. The selected subcarrier decoder delivers the data bit stream and the data
clock as outputs.
The TRF7960A includes a receiver framing engine. This receiver framing engine performs the CRC and/or
parity check, removes the EOF and SOF settings, and organizes the data in bytes for ISO-14443-A/B,
ISO-15693, and NFC Forum protocols. Framed data is then accessible to the microcontroller (MCU) via a
12-byte FIFO register.
A parallel or serial interface (SPI) can be used for the communication between the MCU and the
TRF7960A reader. When the built-in hardware encoders and decoders are used, transmit and receive
functions use a 12-byte FIFO register. For direct transmit or receive functions, the encoders or decoders
can be bypassed so the MCU can process the data in real time. The TRF7960A supports data
communication levels from 1.8 V to 5.5 V for the MCU I/O interface. The transmitter has selectable output
power levels of 100 mW (+20 dBm) or 200 mW (+23 dBm) equivalent into a 50-Ω load when using a 5-V
supply.
2
Introduction
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VDD
VDD_X VDD_I/O
VDD
TX_OUT
Matching
MCU
(MSP430/ARM)
Parallel
or SPI
TRF7960A
RX_IN 1
RX_IN 2
VSS
VIN
XIN
Supply
2.7 V to 5.5 V
Crystal
13.56 MHz
Figure 1-2. Application Block Diagram
The transmitter supports OOK and ASK modulation with selectable modulation depth. The TRF7960A
includes a data transmission engine that supports low-level encoding for ISO-15693 and modified Miller
encoding for ISO14443A/B and FeliCa. Included with the transmit data coding is the automatic generation
of Start Of Frame (SOF), End Of Frame (EOF), Cyclic Redundancy Check (CRC), and parity bits. Several
integrated voltage regulators ensure a proper power-supply noise rejection for the complete reader
system. The built-in programmable auxiliary voltage regulator VDD_X (pin 32) delivers up to 20 mA to
supply a microcontroller and additional external circuits within the reader system.
Table 1-1. Supported Protocols
Supported Protocols
Device
TRF7960A
1.4
ISO14443A/B
106 kbps
212 kbps
424 kbps
848 kbps
✓
✓
✓
✓
TRF7960ARHBT
TRF7960ARHBR
(2)
ISO-18000-3
Mode 1
NFC Forum
Types 1 to 4
✓
✓
✓
Ordering Information
Packaged Devices (1)
(1)
ISO-15693
Package Type (2)
Transport Media
RHB-32
Tape and Reel
Quantity
250
3000
For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
Web site at www.ti.com.
Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at
www.ti.com/sc/package.
Introduction
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1
2
3
4
..............................................
1.1
Features ..............................................
1.2
Applications ..........................................
1.3
Description ...........................................
1.4
Ordering Information .................................
Physical Characteristics ...............................
2.1
Device Pinout ........................................
2.2
Terminal Functions ...................................
Electrical Characteristics ..............................
3.1
Absolute Maximum Ratings ..........................
3.2
Dissipation Ratings ..................................
3.3
Recommended Operating Conditions ...............
3.4
Electrical Characteristics .............................
3.5
Switching Characteristics ............................
Introduction
4.2
4
1
5.1
1
5.2
1
5.3
1
5.4
3
5.5
5
5.6
5
5.7
5
5.8
7
5.9
7
5.10
5.11
7
7
8
9
Application Schematic and Layout
Considerations ......................................... 10
4.1
5
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TRF7960A Reader System Using Parallel
Microcontroller Interface ............................ 10
TRF7960A Reader System Using SPI With SS
Mode ................................................ 11
Detailed System Description
........................
12
6
7
.............................
.....................................
Supply Arrangements ...............................
Supply Regulator Settings ..........................
Power Modes .......................................
Receiver - Analog Section ..........................
Receiver - Digital Section ...........................
Oscillator Section ...................................
Transmitter - Analog Section .......................
Transmitter - Digital Section ........................
System Block Diagram
12
Power Supplies
12
12
14
15
17
18
21
22
23
Transmitter – External Power Amplifier / Subcarrier
detector ............................................. 24
...............
...........
Register Description ..................................
6.1
Register Overview ..................................
System Design .........................................
7.1
Layout Considerations ..............................
7.2
Impedance Matching TX_Out (Pin 5) to 50 Ω ......
7.3
Reader Antenna Design Guidelines ................
5.12
TRF7960A Communication Interface
5.13
Direct Commands from MCU to Reader
Contents
24
42
46
46
62
62
62
63
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2 Physical Characteristics
2.1
Device Pinout
VDD_X
OSC_IN
OSC_OUT
VSS_D
EN
SYS_CLK
DATA_CLK
EN2
RHB PACKAGE
(TOP VIEW)
1
32 31 30 29 28 27 26 25
24
2
3
23
22
4
5
6
21
Thermal Pad
(Connect to Ground) 20
19
7
18
8
17
9 10 11 12 13 14 15 16
I/O_7
I/O_6
I/O_5
I/O_4
I/O_3
I/O_2
I/O_1
I/O_0
RX_IN2
VSS
BG
ASK/OOK
IRQ
MOD
VSS_A
VDD_I/O
VDD_A
VIN
VDD_RF
VDD_PA
TX_OUT
VSS_PA
VSS_RX
RX_IN1
Figure 2-1. TRF7960A Pin Assignment
2.2
Terminal Functions
Table 2-1. Terminal Functions
Terminal
Name
No.
VDD_A
1
VIN
VDD_RF
Type (1)
Description
OUT
Internal regulated supply (2.7 V to 3.4 V) for analog circuitry
2
SUP
External supply input to chip (2.7 V to 5.5 V)
3
OUT
Internal regulated supply (2.7 V to 5 V); normally connected to VDD_PA (pin 4)
VDD_PA
4
INP
Supply for PA; normally connected externally to VDD_RF (pin 3)
TX_OUT
5
OUT
RF output (selectable output power: 100 mW or 200 mW, with VDD = 5 V)
VSS_PA
6
SUP
Negative supply for PA; normally connected to circuit ground
VSS_RX
7
SUP
Negative supply for receive inputs; normally connected to circuit ground
RX_IN1
8
INP
Main receive input
RX_IN2
9
INP
Auxiliary receive input
VSS
10
SUP
Chip substrate ground
BAND_GAP
11
OUT
Bandgap voltage (VBG = 1.6 V); internal analog voltage reference
ASK/OOK
12
BID
Selection between ASK and OOK modulation (0 = ASK, 1 = OOK) for Direct Mode 0 and 1.
It can be configured as an output to provide the received analog signal output.
IRQ
13
OUT
Interrupt request
MOD
14
VSS_A
INP
External data modulation input for Direct Mode 0 or 1
OUT
Subcarrier digital data output (see register 0x1A and 0x1B definitions)
15
SUP
Negative supply for internal analog circuits; connected to GND
VDD_I/O
16
INP
Supply for I/O communications (1.8 V to VIN) level shifter. VIN should be never exceeded.
I/O_0
17
BID
I/O pin for parallel communication
(1)
SUP = Supply, INP = Input, BID = Bidirectional, OUT = Output
Physical Characteristics
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Table 2-1. Terminal Functions (continued)
Terminal
Name
No.
Type (1)
Description
I/O_1
18
BID
I/O pin for parallel communication
I/O_2
19
BID
I/O pin for parallel communication
I/O_3
20
BID
I/O pin for parallel communication
I/O_4
21
BID
I/O pin for parallel communication
Slave select signal in SPI mode
I/O_5
22
BID
I/O pin for parallel communication
Data clock output in Direct Mode 1
I/O_6
23
BID
I/O pin for parallel communication
MISO for serial communication (SPI)
Serial bit data output in Direct Mode 1 or subcarrier signal in Direct Mode 0
I/O_7
24
BID
I/O pin for parallel communication.
MOSI for serial communication (SPI)
EN2
25
INP
Selection of power down mode. If EN2 is connected to VIN, then VDD_X is active during power
down mode 2 (for example, to supply the MCU).
DATA_CLK
26
INP
Data clock input for MCU communication (parallel and serial)
SYS_CLK
27
OUT
If EN = 1 (EN2 = don't care) the system clock for the MCU is configured with register 0x09 (off, 3.39
MHz, 6.78 MHz, or 13.56 MHz).
If EN = 0 and EN2 = 1, the system clock is set to 60 kHz
EN
28
INP
Chip enable input (If EN = 0, then the chip is in sleep or power-down mode)
VSS_D
29
SUP
Negative supply for internal digital circuits
OSC_OUT
30
OUT
Crystal or oscillator output
OSC_IN
31
INP
Crystal or oscillator input
VDD_X
32
OUT
Internally regulated supply (2.7 V to 3.4 V) for digital circuit and external devices (for example, an
MCU)
PAD
SUP
Chip substrate ground
PAD
6
Physical Characteristics
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3 Electrical Characteristics
Absolute Maximum Ratings (1)
3.1
over operating free-air temperature range (unless otherwise noted) (2)
VIN
Input voltage range
IIN
Maximum current
ESD
Electrostatic discharge rating
-0.3 V to 6 V
150 mA
Human-body model (HBM)
2 kV
Charged-device model (CDM)
Maximum operating virtual junction temperature (3)
TJ
TSTG
(1)
(2)
(3)
3.2
(1)
(2)
3.3
500 V
Machine model (MM)
200 V
Any condition
140°C
Continuous operation, long-term reliability
125°C
Storage temperature range
300°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only and functional operation of the device at these or any other conditions beyond those indicated under Operating Conditions are not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltage values are with respect to substrate ground terminal VSS.
The maximum junction temperature for continuous operation is limited by package constraints. Operation above this temperature may
result in reduced reliability and/or lifetime of the device.
Dissipation Ratings
POWER RATING (2)
PACKAGE
θJC
(˚C/W)
θJC (1)
(˚C/W)
TA ≤ 25 ˚C
TA ≤ 85 ˚C
RHB (32)
31
36.4
27 W
1.1 W
This data was taken using the JEDEC standard high-K test PCB.
Power rating is determined with a junction temperature of 125°C. This is the point where distortion starts to increase substantially.
Thermal management of the final PCB should strive to keep the junction temperature at or below 125°C for best performance and
long-term reliability.
Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
TYP
MAX
VIN
Operating input voltage
2.7
5
5.5
V
TA
Operating ambient temperature
-40
25
110
°C
TJ
Operating virtual junction temperature
-40
25
125
°C
Electrical Characteristics
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3.4
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Electrical Characteristics
TA = 25°C, VIN = 5 V, full-power mode (unless otherwise noted)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNIT
<0.5
5
µA
IPD1
Supply current in Power Down Mode 1
All building blocks disabled, including
supply-voltage regulators; measured after
500-ms settling time (EN = 0, EN2 = 0)
IPD2
Supply current in Power Down Mode 2
(Sleep Mode)
The SYS_CLK generator and VDD_X remain
active to support external circuitry, measured
after 100-ms settling time (EN = 0, EN2 = 1)
120
200
µA
ISTBY
Supply current in stand-by mode
Oscillator running, supply-voltage regulators in
low-consumption mode (EN = 1, EN2 = x)
1.9
3.5
mA
ION1
Supply current without antenna driver
current
Oscillator, regulators, RX, and AGC are active,
TX is off
10.5
14
mA
ION2
Supply current – TX (half power)
Oscillator, regulators, RX, AGC, and TX
active, POUT = 100 mW
70
78
mA
ION3
Supply current – TX (full power)
Oscillator, regulators, RX, AGC, and TX
active, POUT = 200 mW
130
170
mA
VPOR
Power-on reset voltage
Input voltage at VIN
1.4
2
2.6
V
VBG
Bandgap voltage (pin 11)
Internal analog reference voltage
1.5
1.6
1.7
V
VDD_A
Regulated output voltage for analog
circuitry (pin 1)
VIN = 5 V
3.1
3.5
3.8
V
VDD_X
Regulated supply for external circuitry
Output voltage pin 32, VIN = 5 V
3.1
3.4
3.8
V
IVDD_Xmax
Maximum output current of VDD_X
Output current pin 32, VIN = 5 V
20
mA
Half power mode, VIN = 2.7 V to 5.5 V
8
12
Ω
Full power mode, VIN = 2.7 V to 5.5 V
4
6
Ω
10
20
kΩ
RRFOUT
Antenna driver output resistance (1)
RRFIN
RX_IN1 and RX_IN2 input resistance
VRF_INmax
Maximum RF input voltage at RX_IN1,
RX_IN2
VRF_INmax should not exceed VIN
3.5
VRF_INmin
Minimum RF input voltage at RX_IN1,
RX_IN2 (input sensitivity) (2)
fSUBCARRIER = 424 kHz
1.4
fSYS_CLK
SYS_CLK frequency
In power mode 2, EN = 0, EN2 = 1
fC
Carrier frequency
Defined by external crystal
tCRYSTAL
Crystal run-in time
Time until oscillator stable bit is set (register
0x0F) (3)
fD_CLKmax
Maximum DATA_CLK frequency (4)
Depends on capacitive load on the I/O lines,
recommendation is 2 MHz (4)
VIL
Input voltage, logic low
I/O lines, IRQ, SYS_CLK, DATA_CLK, EN,
EN2
0.2
VDD_I/O
V
VIH
Input voltage threshold, logic high
I/O lines, IRQ, SYS_CLK, DATA_CLK, EN,
EN2
0.8
VDD_I/O
V
ROUT
Output resistance, I/O_0 to I/O_7
500
800
Ω
RSYS_CLK
Output resistance RSYS_CLK
200
400
Ω
4
fSUBCARRIER = 848 kHz
(1)
(2)
(3)
(4)
8
25
Vpp
2.5
mVpp
2.1
3
mVpp
60
120
13.56
MHz
5
2
8
kHz
ms
10
MHz
Antenna driver output resistance
Measured with subcarrier signal at RX_IN1/2 and measured the digital output at MOD pin with register 0x1A bit 6 = 1
Depending on the crystal parameters and components
Recommended DATA_CLK speed is 2 MHz; higher data clock depends on the capacitive load. Maximum SPI clock speed should not
exceed 10 MHz. This clock speed is acceptable only when external capacitive load is less than 30 pF. MISO driver has a typical output
resistance of 400 Ω (12-ns time constant when 30-pF load is used).
Electrical Characteristics
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3.5
Switching Characteristics
over operating free-air temperature range (unless otherwise noted)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNIT
50
62.5
250
ns
tLO/HI
DATA_CLK time, high or low (one half
Depends on capacitive load on the I/O lines (1)
of DATA_CLK at 50% duty cycle)
tSTE,LEAD
Slave select lead time, slave select
low to clock
200
ns
tSTE,LAG
Slave select lag time, last clock to
slave select high
200
ns
tSU,SI
MOSI input data setup time
15
ns
tHD,SI
MOSI input data hold time
15
ns
tSU,SO
MISO input data setup time
15
ns
tHD,SO
MISO input data hold time
15
tVALID,SO
MISO output data valid time
(1)
DATA_CLK edge to MISO valid, CL = <30 pF
30
ns
50
75
ns
Recommended DATA_CLK speed is 2 MHz; higher data clock depends on the capacitive load. Maximum SPI clock speed should not
exceed 10 MHz. This clock speed is acceptable only when external capacitive load is less than 30 pF. MISO driver has a typical output
resistance of 400 Ω (12-ns time constant when 30-pF load is used).
Electrical Characteristics
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4 Application Schematic and Layout Considerations
4.1
4.1.1
TRF7960A Reader System Using Parallel Microcontroller Interface
General Application Considerations
Figure 4-1 shows the most flexible TRF7960A application. Both ISO15693 and ISO14443 systems can be
addressed. Due to the low clock frequency on the DATA_CLK line, the parallel interface is the most robust
way to connect the TRF7960A with the MCU.
This schematic shows matching to a 50-Ω port, which allows connection to a properly matched 50-Ω
antenna circuit or RF measurement equipment (for example, a spectrum analyzer or power meter).
4.1.2
Schematic
Figure 4-1 shows a sample application schematic with a parallel interface to the MCU.
Figure 4-1. Application Schematic, Parallel MCU Interface
The MSP430F2370 (32kB flash, 2kB RAM) is shown in Figure 4-1. Minimum MCU requirements depend
on application requirements and coding style. If only one ISO protocol and/or a limited command set of a
protocol must be supported, MCU flash and RAM requirements can be significantly reduced. Note that
recursive inventory and anti-collision commands require more RAM than single slotted operations. For
example, current reference firmware for ISO15693 (with host interface) is approximately 8kB, using 512B
RAM and for all supported protocols (also with same host interface) the reference firmware is
approximately 12kB, using a minimum of 1kB RAM. An MCU that is capable of running a GPIO at
13.56 MHz is required for Direct Mode 0 operations with non-standard transponders.
10
Application Schematic and Layout Considerations
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4.2
4.2.1
TRF7960A Reader System Using SPI With SS Mode
General Application Considerations
Figure 4-2 shows the TRF7960A application schematic optimized for both ISO15693 and ISO14443
systems using the Serial Port Interface (SPI). Short SPI lines, proper isolation to radio frequency lines,
and a proper ground area are essential to avoid interference. The recommended clock frequency on the
DATA_CLK line is 2 MHz.
This schematic shows matching to a 50-Ω port, which allows connection to a properly matched 50-Ω
antenna circuit or RF measurement equipment (for example, a spectrum analyzer or power meter).
4.2.2
Schematic
Figure 4-2 shows a sample application schematic with a serial interface to the MCU.
Figure 4-2. Application Schematic, SPI With SS Mode MCU Interface
The MSP430F2370 (32kB flash, 2kB RAM) is shown in Figure 4-2. Minimum MCU requirements depend
on application requirements and coding style. If only one ISO protocol and/or a limited command set of a
protocol must be supported, MCU flash and RAM requirements can be significantly reduced and user
should be aware that recursive inventory/anti-collision commands require more RAM than single slotted
operations. For example, current reference firmware for ISO15693 (with host interface) is approximately
8kB, using 512B RAM and for all supported protocols (also with same host interface) the reference
firmware is approximately 12kB, using minimum 1kB RAM. MCU capable of running GPIO at 13.56 MHz
required for Direct Mode 0 operations with non-standard transponders.
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5 Detailed System Description
5.1
System Block Diagram
VDD _I/O
MUX
RX_IN1
Phase and
Amplitude
Detector
RSSI
(AUX)
RSSI
(External)
RX_IN2
Phase and
Amplitude
Detector
VDD_PA
TX_ OUT
Gain
Transmitter Analog
Front End
Gain
RSSI
(Main)
Filter,
AGC
Digitizer
ISO
Protocol
Handling
Decoder
Bit
Framing
Framing
Logic
I/O_0
State
Control
Logic
(Control
Registers,
Command
Logic)
I/O_1
I/O_5
I/O_7
12-Byte
FIFO
SYS _CLK
DATA _CLK
VIN
VDD _A
BAND _GAP
VSS _A
EN2
Digital Control
State Machine
ASK/ OOK
MOD
VDD _RF
Voltage Supply Regulator Systems
(Supply Regulators, Reference Voltages)
OSC_ OUT
I/O_4
Level
Shifter
IRQ
EN
OSC_IN
I/O_3
I/O_6
MCU
Interface
Serial
Conversion
CRC, Parity
VSS_PA
I/O_2
VSS _RF
VDD_X
VSS
Crystal Oscillator
Timing System
VSS _D
Figure 5-1. System Block Diagram
5.2
Power Supplies
The TRF7960A positive supply input VIN (pin 2) sources three internal regulators with output voltages
VDD_RF, VDD_A, and VDD_X. All regulators require external bypass capacitors for supply noise filtering
and must be connected as indicated in reference schematics. These regulators provide a high power
supply reject ratio (PSRR) as required for RFID reader systems. All regulators are supplied via VIN (pin 2).
The regulators are not independent and have common control bits in register 0x0B for output voltage
setting. The regulators can be configured to operate in either automatic or manual mode (register 0x0B, bit
7). The automatic regulator setting mode ensures an optimal compromise between PSRR and the highest
possible supply voltage for RF output (to ensure maximum RF power output). The manual mode allows
the user to manually configure the regulator settings.
5.3
Supply Arrangements
Regulator Supply Input: VIN
The positive supply at VIN (pin 2) has an input voltage range of 2.7 V to 5.5 V. VIN provides the supply
input sources for three internal regulators with the output voltages VDD_RF, VDD_A, and VDD_X.
External bypass capacitors for supply noise filtering must be used (per reference schematics).
NOTE
VIN must be the highest voltage supplied to the TRF7960A.
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RF Power Amplifier Regulator: VDD_RF
The VDD_RF (pin 3) regulator is supplying the RF power amplifier. The voltage regulator can be set for
either 5V or 3V operation. External bypass capacitors for supply noise filtering must be used (per
reference schematics). When configured for 5V manual-operation, the VDD_RF output voltage can be set
from 4.3 V to 5 V in 100-mV steps. In 3-V manual operation, the output can be programmed from 2.7 V to
3.4 V in 100-mV steps (see Table 5-2). The maximum output current capability for 5-V operation is 150
mA and for 3-V operation is 100 mA.
Analog Supply Regulator: VDD_A
Regulator VDD_A (pin 1) supplies the analog circuits of the device. The output voltage setting depends on
the input voltage and can be set for 5-V and 3-V operation. When configured for 5-V manual operation,
the output voltage is fixed at 3.4 V. External bypass capacitors for supply noise filtering must be used (per
reference schematics). When configured for 3-V manual operation, the VDD_A output can be set from 2.7
V to 3.4 V in 100-mV steps (see Table 5-2).
NOTE
The configuration of VDD_A and VDD_X regulators are not independent from each other.
The VDD_A output current should not exceed 20 mA.
Digital Supply Regulator: VDD_X
The Digital Supply Regulator VDD_X (pin 32) provides the power for the internal digital building blocks
and can also be used to supply external electronics within the reader system. When configured for 3-V
operation, the output voltage can be set from 2.7 to 3.4 V in 100-mV steps. External bypass capacitors for
supply noise filtering must be used (per reference schematics).
NOTE
The configuration of the VDD_A and VDD_X regulators are not independent from each other.
The VDD_X output current should not exceed 20 mA.
The RF power amplifier regulator (VDD_RF), analog supply regulator (VDD_A), and digital supply
regulator (VDD_X) can be configured to operate in either automatic or manual mode described in
Table 5-1. The automatic regulator setting mode ensures an optimal compromise between PSRR and the
highest possible supply voltage to ensure maximum RF power output.
By default, the regulators are set in automatic regulator setting mode. In this mode, the regulators are
automatically set every time the system is activated by setting EN input High or each time the automatic
regulator setting bit, B7 in register 0x0B is set to a 1. The action is started on the 0 to 1 transition. This
means that, if the user wants to re-run the automatic setting from a state in which the automatic setting bit
is already high, the automatic setting bit (B7 in register 0x0B) should be changed: 1-0-1.
By default, the regulator setting algorithm sets the regulator outputs to a "Delta Voltage" of 250 mV below
VIN, but not higher than 5 V for VDD_RF and 3.4 V for VDD_A and VDD_A. The "Delta Voltage" in
automatic regulator mode can be increased up to 400 mV (for more details, see bits B0 to B2 in register
0x0B).
Power Amplifier Supply: VDD_PA
The power amplifier of the TRF7960A is supplied through VDD_PA (pin 4). The positive supply pin for the
RF power amplifier is externally connected to the regulator output VDD_RF (pin 3).
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I/O Level Shifter Supply: VDD_I/O
The TRF7960A has a separate supply input VDD_I/O (pin 16) for the build in I/O level shifter. The
supported input voltage ranges from 1.8 V to VIN, however not exceeding 5.5 V. Pin 16 is used to supply
the I/O interface pins (I/O_0 to I/O_7), IRQ, SYS_CLK, and DATA_CLK pins of the reader. In typical
applications, VDD_I/O is directly connected to VDD_X while VDD_X also supplies the MCU. This ensures
that the I/O signal levels of the MCU match with the logic levels of the TRF7960A.
Negative Supply Connections: VSS, VSS_RX, VSS_A, VSS_PA
The negative supply connections VSS_X of each functional block are all externally connected to GND.
The substrate connection is VSS (pin 10), the analog negative supply is VSS_A (pin 15), the logic
negative supply is VSS_D (pin 29), the RF output stage negative supply is VSS_PA (pin 6), and the
negative supply for the RF receiver VSS_RX (pin 7).
5.4
Supply Regulator Settings
The input supply voltage mode of the reader must be selected. This is done in the Chip Status Control
register (0x00). Bit 0 in register 0x00 selects between 5-V or 3-V input supply voltage. The default
configuration is 5 V, which reflects an operating supply voltage range of 4.3 V to 5.5 V. If the supply
voltage is below 4.3 V, the 3-V configuration should be used.
The various regulators can be configured to operate in automatic or manual mode. This is done in the
Regulator and I/O Control register 0x0B as shown in Table 5-1.
Table 5-1. Supply Regulator Setting: 5-V System
Register
Address
Option Bits Setting in Regulator Control Register (1)
B7
B6
B5
B4
B3
B2
B1
B0
Comments
Automatic Mode (default)
0B
1
x
x
x
x
x
1
1
Automatic regulator setting 250-mV difference
0B
1
x
x
x
x
x
1
0
Automatic regulator setting 350-mV difference
0B
1
x
x
x
x
x
0
0
Automatic regulator setting 400-mV difference
0B
0
x
x
x
x
1
1
1
VDD_RF = 5 V, VDD_A = 3.4 V, VDD_X = 3.4 V
0B
0
x
x
x
x
1
1
0
VDD_RF = 4.9 V, VDD_A = 3.4 V, VDD_X = 3.4 V
0B
0
x
x
x
x
1
0
1
VDD_RF = 4.8 V, VDD_A = 3.4 V, VDD_X = 3.4 V
0B
0
x
x
x
x
1
0
0
VDD_RF = 4.7 V, VDD_A = 3.4 V, VDD_X = 3.4 V
0B
0
x
x
x
x
0
1
1
VDD_RF = 4.6 V, VDD_A = 3.4 V, VDD_X = 3.4 V
0B
0
x
x
x
x
0
1
0
VDD_RF = 4.5 V, VDD_A = 3.4 V, VDD_X = 3.4 V
0B
0
x
x
x
x
0
0
1
VDD_RF = 4.4 V, VDD_A = 3.4 V, VDD_X = 3.4 V
0B
0
x
x
x
x
0
0
0
VDD_RF = 4.3 V, VDD_A = 3.4 V, VDD_X = 3.4 V
Manual Mode
(1)
14
x = don't care
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Table 5-2. Supply Regulator Setting: 3-V System
Register
Address
Option Bits Setting in Regulator Control Register (1)
B7
B6
B5
B4
B3
B2
B1
B0
Comments
Automatic Mode (default)
0B
1
x
x
x
x
x
1
1
Automatic regulator setting 250-mV difference
0B
1
x
x
x
x
x
1
0
Automatic regulator setting 350-mV difference
0B
1
x
x
x
x
x
0
0
Automatic regulator setting 400-mV difference
0B
0
x
x
x
x
1
1
1
VDD_RF = 3.4 V, VDD_A = 3.4 V, VDD_X = 3.4 V
0B
0
x
x
x
x
1
1
0
VDD_RF = 3.3 V, VDD_A = 3.3 V, VDD_X = 3.3 V
0B
0
x
x
x
x
1
0
1
VDD_RF = 3.2 V, VDD_A = 3.2 V, VDD_X = 3.2 V
0B
0
x
x
x
x
1
0
0
VDD_RF = 3.1 V, VDD_A = 3.1 V, VDD_X = 3.1 V
0B
0
x
x
x
x
0
1
1
VDD_RF = 3.0 V, VDD_A = 3.0 V, VDD_X = 3.0 V
0B
0
x
x
x
x
0
1
0
VDD_RF = 2.9 V, VDD_A = 2.9 V, VDD_X = 2.9 V
0B
0
x
x
x
x
0
0
1
VDD_RF = 2.8 V, VDD_A = 2.8 V, VDD_X = 2.8 V
0B
0
x
x
x
x
0
0
0
VDD_RF = 2.7 V, VDD_A = 2.7 V, VDD_X = 2.7 V
Manual Mode
(1)
x = don't care
The regulator configuration function adjusts the regulator outputs by default to 250 mV below VIN level,
but not higher than 5 V for VDD_RF, 3.4 V for VDD_A and VDD_X. This ensures the highest possible
supply voltage for the RF output stage while maintaining an adequate PSRR (power supply rejection
ratio).
To further improve the PSRR, it is possible to increase the target voltage difference across VDD_X and
VDD_A from its default to 350 mV or even 400 mV (for details, see Regulator and I/O Control register
0x0B definition and Table 5-2.)
5.5
Power Modes
The chip has several power states, which are controlled by two input pins (EN and EN2) and several bits
in the Chip Status Control register (0x00).
Table 5-3 is a consolidated table showing the configuration for the different power modes when using a
5-V or 3-V system supply. The main reader enable signal is pin EN. When EN is set high, all of the reader
regulators are enabled, the 13.56-MHz oscillator is running and the SYS_CLK (output clock for external
microcontroller) is also available.
The Regulator Control register settings shown are for optimized power out. The automatic setting
(normally 0x87) is optimized for best PSRR and noise reduction.
Table 5-3. Power Modes (1)
Mode
EN2
EN
Chip
Status
Control
Register
(0x00)
Mode 4
(Full Power)
5 VDC
x
1
21
07
On
On
On
x
On
130
23
Mode 4
(Full Power)
3.3 VDC
x
1
20
07
On
On
On
x
On
67
18
Mode 3
(Half Power)
5 VDC
x
1
31
07
On
On
On
x
On
70
20
Mode 3
(Half Power)
3.3 VDC
x
1
30
07
On
On
On
x
On
53
15
(1)
Regulator
Control
Register
(0x0B)
Transmitter
Receiver
SYS_CLK
(13.56
MHz)
SYS_CLK
(60 kHz)
VDD_X
Typical
Current
(mA)
Typical
Power
Out
(dBm)
Time
(From
Previous
State)
~20-25 µs
~20-25 µs
x = don't care
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Table 5-3. Power Modes(1) (continued)
Mode
EN2
EN
Chip
Status
Control
Register
(0x00)
Mode 2
5 VDC
x
1
03
07
Off
On
On
x
On
10.5
—
Mode 2
3.3 VDC
x
1
02
00
Off
On
On
x
On
9
—
Mode 1
5 VDC
x
1
01
07
Off
Off
On
x
On
5
—
~20-25 µs
Mode 1
3.3 VDC
x
1
00
00
Off
Off
On
x
On
3
Standby Mode
5 VDC
x
1
81
07
Off
Off
On
x
On
3
—
4.8 ms
Standby Mode
3.3 VDC
x
1
80
00
Off
Off
On
x
On
2
—
Sleep Mode
1
0
x
x
Off
Off
Off
On
On
0.120
—
1.5 ms
Power Down
0
0
x
x
Off
Off
Off
Off
Off
<0.001
—
Start
Regulator
Control
Register
(0x0B)
Transmitter
Receiver
SYS_CLK
(13.56
MHz)
SYS_CLK
(60 kHz)
VDD_X
Typical
Current
(mA)
Typical
Power
Out
(dBm)
Time
(From
Previous
State)
~20-25 µs
The input pin EN2 has two functions:
• A direct connection from EN2 to VIN to ensure the availability of the regulated supply VDD_X and an
auxiliary clock signal (60 kHz, SYS_CLK) for an external MCU. This mode (EN = 0, EN2 = 1) is
intended for systems in which the MCU is also being supplied by the reader supply regulator (VDD_X)
and the MCU clock is supplied by the SYS_CLK output of the reader. This allows the MCU supply and
clock to be available during sleep mode.
• EN2 enables the start-up of the reader system from complete power down (EN = 0, EN2 = 0). In this
case, the EN input is being controlled by the MCU (or other system device) that is without supply
voltage during complete power down (thus unable to control the EN input). A rising edge applied to the
EN2 input (which has an approximately 1-V threshold level) starts the reader supply system and
13.56-MHz oscillator (identical to condition EN = 1).
When user MCU is controlling EN and EN2, a delay of 5 ms between EN and EN2 must be used. In cases
where MCU is only controlling EN, EN2 is recommended to be connected to either VIN or GND,
depending on the application MCU requirements/needs for VDD_X and SYS_CLK.
NOTE
Using EN=1 and EN2=1 in parallel at start up should not be done as it may cause incorrect
operation.
This start-up mode lasts until all of the regulators have settled and the 13.56-MHz oscillator has stabilized.
If the EN input is set high (EN = 1) by the MCU (or other system device), the reader stays active. If the EN
input is not set high (EN = 0) within 100 µs after the SYS_CLK output is switched from auxiliary clock (60
kHz) to high-frequency clock (derived from the crystal oscillator), the reader system returns to complete
Power-Down Mode 1. This option can be used to wake the reader system from complete Power Down
(PD Mode 1) by using a pushbutton switch or by sending a single pulse.
After the reader EN line is high, the other power modes are selected by control bits within the Chip Status
Control register (0x00). The power mode options and states are listed in Table 5-3.
When EN is set high (or on rising edge of EN2 and then confirmed by EN = 1) the supply regulators are
activated and the 13.56-MHz oscillator started. When the supplies are settled and the oscillator frequency
is stable, the SYS_CLK output is switched from the auxiliary frequency of 60 kHz to the 13.56-MHz
frequency derived from the crystal oscillator. At this time, the reader is ready to communicate and perform
the required tasks. The MCU can then program the Chip Status Control register 0x00 and select the
operation mode by programming the additional registers.
16
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•
•
•
•
5.6
5.6.1
Stand-by Mode (bit 7 = 1 of register 0x00), the reader is capable of recovering to full operation in
100 µs.
Mode 1 (active mode with RF output disabled, bit 5 = 0 and bit 1 = 0 of register 0x00) is a low-power
mode that allows the reader to recover to full operation within 25 µs.
Mode 2 (active mode with only the RF receiver active, bit 1 = 1 of register 0x00) can be used to
measure the external RF field (as described in RSSI measurements paragraph) if reader-to-reader
anti-collision is implemented.
Mode 3 and Mode 4 (active modes with the entire RF section active, bit 5 = 1 of register 0x00) are the
normal modes used for normal transmit and receive operations.
Receiver - Analog Section
Main and Auxiliary Receiver
The TRF7960A has two receiver inputs: RX_IN1 (pin 8) and RX_IN2 (pin 9). Each of the input is
connected to an external capacitive voltage divider to ensure that the modulated signal from the tag is
available on at least one of the two inputs. This architecture eliminates any possible communication holes
that may occur from the tag to the reader.
The two RX inputs (RX_IN1 and RX_IN2) are multiplexed into two receivers–the main receiver and the
auxiliary receiver. Only the main receiver is used for reception; the auxiliary receiver is used for signal
quality monitoring. Receiver input multiplexing is controlled by bit B3 in the Chip Status Control register
(address 0x00).
After startup, RX_IN1 is multiplexed to the main receiver which is composed of an RF envelope detection,
first gain and band-pass filtering stage, second gain and filtering stage with AGC. Only the main receiver
is connected to the digitizing stage which output is connected to the digital processing block. The main
receiver also has an RSSI measuring stage, which measures the strength of the demodulated signal
(subcarrier signal).
The primary function of the auxiliary receiver is to monitor the RX signal quality by measuring the RSSI of
the demodulated subcarrier signal (internal RSSI). After startup, RX_IN2 is multiplexed to the auxiliary
receiver. The auxiliary receiver has an RF envelope detection stage, first gain and filtering with AGC stage
and finally the auxiliary RSSI block.
The default MUX setting is RX_IN1 connected to the main receiver and RX_IN2 connected to the auxiliary
receiver. To determine the signal quality, the response from the tag is detected by the "main" (pin RX_IN1)
and "auxiliary" (pin RX_IN2) RSSI. Both values measured and stored in the RSSI level register (address
0x0F). The MCU can read the RSSI values from the TRF7960A RSSI register and decide if swapping the
input signals is preferable or not. Setting B3 in the Chip Status Control register (address 0x00) to 1
connects RX_IN1 (pin 8) to the auxiliary receiver and RX_IN2 (pin 9) to the main receiver. This
mechanism must be used to avoid reading holes.
The main and auxiliary receiver input stages are RF envelope detectors. The RF amplitude at RX_IN1 and
RX_IN2 should be approximately 3 VPP for a VIN supply level greater than 3.3 V. If the VIN level is lower,
the RF input peak-to-peak voltage level should not exceed the VIN level.
5.6.2
Receiver Gain and Filter Stages
The first gain and filtering stage has a nominal gain of 15 dB with an adjustable band-pass filter. The
band-pass filter has programmable 3-dB corner frequencies between 110 kHz to 450 kHz for the
high-pass filter and 570 kHz to 1500 kHz for the low-pass filter. After the band-pass filter, there is another
gain-and-filtering stage with a nominal gain of 8 dB and with frequency characteristics identical to the first
band-pass stage.
The internal filters are configured automatically depending on the selected ISO communication standard in
the ISO Control register (address 0x01). If required, additional fine tuning can be done by writing directly
to the RX special setting registers (address 0x0A).
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The main receiver also has a second receiver gain and digitizer stage which is included in the AGC loop.
The AGC loop is activated by setting the bit B2 = 1 in the Chip Status Control register (address 0x00).
When activated, the AGC continuously monitors the input signal level. If the signal level is significantly
higher than an internal threshold level, gain reduction is activated.
By default, the AGC is frozen after the first four pulses of the subcarrier signal. This prevents the AGC
from interfering with the reception of the remaining data packet. In certain situations, this "AGC freeze" is
not optimal, so it can be removed by setting B0 = 1 in the RX Special Setting register (address 0x0A).
Table 5-4 shows the various settings for the receiver analog section. It is important to note that setting B4,
B5, B6, and B7 to 0 results to a band-pass characteristic of 240 kHz to 1.4 MHz, which is appropriate for
ISO14443B 106 kbps, ISO14443A/B data-rates of 212 kbps and 424 kbps, and FeliCa 424 kbps.
Table 5-4. RX Special Setting Register (0x0A)
Bit
Function
Comments
B7
Bandpass from 110 kHz to 570 kHz
Appropriate for any 212-kHz subcarrier systems like FeliCa
B6
Bandpass from 200 kHz to 900 kHz
Appropriate for 424-kHz subcarrier systems (for example, used in ISO15693).
B5
Bandpass from 450 kHz to 1.5 MHz
Appropriate for Manchester-coded 106-kbps 848-kHz subcarrier systems (for
example, used in ISO14443A).
B4
Bandpass from 100 kHz to 1.5 MHz
Appropriate for highest bit rate (848 kbps) used in high-bit-rate ISO14443B. Gain
is reduced by 7 dB.
B3
00
01
10
11
Sets the RX digital gain reduction (changing the window of the digitizing
comparator).
B2
= no gain reduction
= gain reduction for 5 dB
= gain reduction for 10 dB
= gain reduction for 15 dB
B1
0 = 5 times minimum digitizing level
1 = 3 times minimum digitizing level
AGC activation level change. From five times higher to the minimum RX digitizing
level to three times the minimum digitizing level. The minimum RX digitizing level
can be adjusted by B2 and B3 (gain reduction).
B0
0 = AGC freeze after 16 subcarrier edges
1 = AGC always on during receive
AGC action is not limited in time or to the start of receive. AGC action can be done
any time during receive process. The AGC can only increase and, hence, clips on
the peak RX level during the enable period. AGC level is reset automatically at the
beginning of each receive start frame.
5.7
Receiver - Digital Section
The output of the TRF7960A analog receiver block is a digitized subcarrier signal and is the input to the
digital receiver block. This block includes a Protocol Bit Decoder section and the Framing Logic section.
The protocol bit decoders convert the subcarrier coded signal into a serial bit stream and a data clock.
The decoder logic is designed for maximum error tolerance. This enables the decoder section to
successfully decode even partly corrupted subcarrier signals that otherwise would be lost due to noise or
interference.
In the framing logic section, the serial bit stream data is formatted in bytes. Special signals such as the
start of frame (SOF), end of frame (EOF), start of communication, and end of communication are
automatically removed. The parity bits and CRC bytes are also checked and removed. This "clean" data is
then sent to the 12-byte FIFO register where it can be read by the external microcontroller system.
Providing the data this way, in conjunction with the timing register settings of the TRF7960A, means the
firmware developer has to know about much less of the finer details of the ISO protocols to create a very
robust application, especially in low-cost platforms where code space is at a premium and high
performance is still required.
The start of the receive operation (successfully received SOF) sets the IRQ flags in the IRQ and Status
register (0x0C). The end of the receive operation is signaled to the external system MCU by setting pin 13
(IRQ) high. If the receive data packet is longer than 8 bytes, an interrupt is sent to the MCU as the
received data occupies 75% of the FIFO capacity. The data should be immediately removed from the
FIFO.
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Any error in the data format, parity, or CRC is detected and notified to the external system by an interrupt
request pulse. The source condition of the interrupt request pulse is available in the IRQ Status register
(0x0C). The main register controlling the digital part of the receiver is the ISO Control register (0x01). By
writing to this register, the user selects the protocol to be used. With each new write in this register, the
default presets are reloaded in all related registers, so no further adjustments in other registers are
needed for proper operation.
NOTE
If register setting changes are needed for fine tuning the system, they must be done after
setting the ISO Control register (0x01).
The framing section also supports the bit-collision detection as specified in ISO14443A (0x01). When a bit
collision is detected, an interrupt request is sent and a flag is set in the IRQ and Status register (0x0C).
The position of the bit collision is written in two registers: Collision Position register (0x0E) and partly in
Collision Position and Interrupt Mask register (0x0D) (bits B6 and B7).
The collision position is presented as sequential bit number, where the count starts immediately after the
start bit. This means a collision in the first bit of a UID would give the value 00 0001 0000 in these
registers when their contents are combined after being read. (the count starts with 0 and the first 16 bits
are the command code and the Number of Valid Bits (NVB) byte)
The receive section also includes two timers. The RX wait time timer is controlled by the value in the RX
Wait Time register (0x08). This timer defines the time interval after the end of the transmit operation in
which the receive decoders are not active (held in reset state). This prevents false detections resulting
from transients following the transmit operation. The value of the RX Wait Time register (0x08) defines the
time in increments of 9.44 µs. This register is preset at every write to ISO Control register (0x01)
according to the minimum tag response time defined by each standard.
The RX no response timer is controlled by the RX No Response Wait Time register (0x07). This timer
measures the time from the start of slot in the anti-collision sequence until the start of tag response. If
there is no tag response in the defined time, an interrupt request is sent and a flag is set in the IRQ Status
register (0x0C). This enables the external controller to be relieved of the task of detecting empty slots. The
wait time is stored in the register in increments of 37.76 µs. This register is also automatically preset for
every new protocol selection.
5.7.1
Received Signal Strength Indicator (RSSI)
The TRF7960A incorporates in total three independent RSSI building blocks: Internal Main RSSI, Internal
Auxiliary RSSI, and External RSSI. The internal RSSI blocks are measuring the amplitude of the
subcarrier signal, and the external RSSI block measures the amplitude of the RF carrier signal at the
receiver input.
5.7.1.1
Internal RSSI – Main and Auxiliary Receivers
Each receiver path has its own RSSI block to measure the envelope of the demodulated RF signal
(subcarrier). Internal Main RSSI and Internal Auxiliary RSSI are identical except that they are connected to
different RF input pins. The Internal RSSI is intended for diagnostic purposes to set the correct RX path
conditions.
The Internal RSSI values can be used to adjust the RX gain settings and/or decide which RX path (main
or auxiliary) provides the greater amplitude and, hence, to decide if the MUX may need to be
reprogrammed to swap the RX input signal. The measuring system latches the peak value, so the RSSI
level can be read after the end of each receive packet. The RSSI register values are reset with every
transmission (TX) by the reader. This guarantees an updated RSSI measurement for each new tag
response.
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The Internal RSSI has 7 steps (3 bit) with a typical increment of about 4 dB. The operating range is
between 600 mVp and 4.2 Vpp with a typical step size of about 600 mV. Both RSSI values "Internal Main"
and "Internal Aux" RSSI are stored in the RSSI Levels and Oscillator Status register (0x0F).
RSSI Levels and Oscillator Status Register Value (0x0F)
The nominal relationship between the input RF peak level and the RSSI value is shown in Figure 5-2.
7
6
5
4
3
2
1
0
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
2.25 2.5 2.75
Input RF Carrier Level (VPP)
3
3.25
3.5
3.75
4
4.25
Figure 5-2. Digital Internal RSSI (Main and Auxiliary) Value vs RF Input Level
This RSSI measurement is done during the communication to the Tag; this means the TX must be on. Bit
1 in the Chip Status Control register (0x00) defines if internal RSSI or the external RSSI value is stored in
the RSSI Levels and Oscillator Status register 0x0F. Direct command 0x18 is used to trigger an internal
RSSI measurement.
5.7.1.2
External RSSI
The external RSSI is mainly used for test and diagnostic in order to sense the amplitude of any
13.56-MHz signal at the receivers RX_IN1 input. The external RSSI measurement is typically done in
active mode when the receiver is on but transmitter output is off. The level of the RF signal received at the
antenna is measured and stored in the RSSI Levels and Oscillator Status Register 0x0F.
The relationship between the voltage at the RX_IN1 input and the 3-bit code is shown in Figure 5-3.
20
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7
6
5
4
3
2
1
0
0
25
50
75
100
125
150
175
200
225
250
275
300
325
RF Input Voltage Level at Pin RF_IN1 (mVPP)
Figure 5-3. Digital External RSSI Value vs RF Input Level
The relation between the 3-bit code and the external RF field strength (A/m) sensed by the antenna must
be determined by calculation or by experiments for each antenna design. The antenna Q-factor and
connection to the RF input influence the result. Direct command 0x19 is used to trigger an internal RSSI
measurement.
To
1.
2.
3.
check the internal or external RSSI value independent of any other operation, the user must:
Set transmitter to desired state (on or off) using Bit 5 of Chip Status Control register (0x00)
Set the receiver using direct command 0x17.
Check internal or external RSSI using direct commands 0x18 or 0x19, respectively.
This action latches/places RSSI value in RSSI register
4. Read RSSI register using direct command 0x0F, values range from 0x40 to 0x7F.
5. Repeat steps 1-4 as desired, as register is reset after read.
5.8
Oscillator Section
The 13.56-MHz oscillator is controlled via the Chip Status Control register (0x00) and the EN and EN2
signals. The oscillator generates the RF frequency for the RF output stage and the clock source for the
digital section. The buffered clock signal is available at pin 27 (SYS_CLK) for external circuits. B4 and B5
inside the Modulation and SYS_CLK register (0x09) can be used to divide the external SYS_CLK signal at
pin 27 by 1, 2, or 4.
Typical start-up time from complete power down is in the range of 3.5 ms.
During Power Down Mode 2 (EN = 0, EN2 = 1) the frequency of SYS_CLK is switched to 60 kHz (typical).
The 13.56-MHz crystal must be connected between pin 31 and pin 32. The external shunt capacitors
values for C1 and C2 must be calculated based on the specified load capacitance of the crystal being
used. The external shunt capacitors are calculated as two identical capacitors in series plus the stray
capacitance of the TRF7960A and parasitic PCB capacitance in parallel to the crystal.
The parasitic capacitance (CS , stray and parasitic PCB capacitance) can be estimated at 4 to 5 pF
(typical).
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As an example, using a crystal with a required load capacitance (CL) of 18 pF, the calculation is as follows
(see Figure 5-4):
C1= C2 = 2 × (CL – CS) = 2 × (18 pF – 4.5 pF) = 27 pF
A 27-pF capacitor must be placed on pins 30 and 31 to ensure proper crystal oscillator operation.
CS
TRF7960A
Pin 32
Pin 31
C1
Crystal
C2
Figure 5-4. Crystal Block Diagram
Table 5-5 shows the minimum characteristics required for any crystal used with TRF7960A.
Table 5-5. TRF7960A Minimum Crystal Requirements
Parameter
Specification
Frequency
13.56 MHz
Mode of operation
Fundamental
Type of resonance
Parallel
Frequency tolerance
± 20 ppm
Aging
< 5 ppm/year
Operation temperature range
-40°C to 85°C
Equivalent series resistance
50 Ω
As an alternative, an external clock oscillator source can be connected to pin 31 to provide the system
clock, and pin 32 can be left open.
5.9
Transmitter - Analog Section
The 13.56-MHz oscillator generates the RF signal for the PA stage. The power amplifier consists of a
driver with selectable output resistance of 4 Ω or 8 Ω (typical). The transmit power levels are selectable
between 100 mW (half power) or 200 mW (full power) when configured for 5-V automatic operation.
Selection of the transmit power level is set by bit B4 in the Chip Status Control register (0x00). When
configured for 3-V automatic operation, the transmit power level is typically in the range of 33 mW (half
power) or 70 mW (full power).
The ASK modulation depth is controlled by bits B0, B1, and B2 in the Modulator and SYS_CLK Control
register (0x09). The ASK modulation depth range can be adjusted between 7% to 30% or 100% (OOK).
External control of the transmit modulation depth is possible by setting the ISO Control register (0x01) to
Direct Mode. While operating the TRF7960A in Direct Mode, the transmit modulation is made possible by
selecting the modulation type ASK or OOK at pin 12. External control of the modulation type is made
possible only if enabled by setting B6 in the Modulator and SYS_CLK Control register (0x09) to 1.
In normal operation mode, the length of the modulation pulse is defined by the protocol selected in the
ISO Control register (0x01). In case of a high-Q antenna, the modulation pulse is typically prolonged, and
the tag detects a longer pulse than intended. For such cases, the modulation pulse length must be
corrected by using the TX Pulse Length register (0x06).
If the register contains all zeros, then the pulse length is governed by the protocol selection. If the register
contains a value other than 0x00, the pulse length is equal to the value of the register multiplied by
73.7 ns. This means the pulse length can be adjusted between 73.7 ns and 18.8 µs in 73.7-ns increments.
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5.10 Transmitter - Digital Section
The digital part of the transmitter is a mirror of the receiver. The settings controlled the ISO Control
register (0x01) are applied to the transmitter just like the receiver. In the TRF7960A default mode (ISO
Mode), the TRF7960A automatically adds all the special signals like start of communication, end of
communication, SOF, EOF, parity bits and CRC bytes.
The data is then coded to modulation pulse levels and sent to the RF output stage modulation control unit.
Just like with the receiver, this means that the external system MCU only has to load the FIFO with data
and all the micro-coding is done automatically, again saving the firmware developer code space and time.
Additionally, all the registers used for transmit parameter control are automatically preset to optimum
values when a new selection is entered into the ISO Control register (0x01).
NOTE
The FIFO must be reset before starting any transmission with Direct Command 0x0F.
There are two ways to start the transmit operation:
• It can be started by loading the number of bytes to be sent (address 0x1D and 0x1E) and data to be
loaded in the FIFO (address 0x1F) followed by a transmit command (described in direct commands
section). In this case, the transmission then starts exactly on the transmit command.
• It is also possible to send the transmit command and information on the number of bytes to be
transmitted first and then start to send the data to FIFO. In this case, the transmission starts when first
data byte is written into the FIFO.
NOTE
If the data length is longer than the FIFO, the external system MCU is warned when the
majority of data from the FIFO was already transmitted by sending and interrupt request with
flag in IRQ register to indicate a FIFO low/high status. The external system should respond
by loading next data packet into the FIFO.
At the end of a transmit operation, the external system MCU is notified by interrupt request (IRQ) with a
flag in IRQ register (0x0C) indicating TX is complete (example value = 0x80).
The TX Length registers also support incomplete byte transmission. The high two nibbles in register 0x1D
and the nibble composed of bits B4 through B7 in register 0x1E store the number of complete bytes to be
transmitted. Bit B0 in register 0x1E is a flag indicating that there are also additional bits to be transmitted
which do not form a complete byte. The number of bits is stored in bits B1 through B3 of the same register
(0x1E).
Some protocols have options so there are two sub-level configuration registers to select the TX protocol
options.
• ISO14443B TX Options register (0x02). It controls the SOF and EOF selection and EGT selection for
the ISO14443B protocol.
• 5.1.2.2 ISO 14443A High-Bit-Rate and Parity Options register (0x03). This register enables the use of
different bit rates for RX and TX operations in ISO14443 high bit rate protocol. Besides that, it also
selects the parity method in case of ISO14443A high bit rate.
The digital section also has a timer. The timer can be used to start the transmit operation at a precise time
in accordance with a selected event. This is necessary if the tag expects a replay in exact time window
following the tag response. This is normally not the case with existing protocols but is needed protocols
when using 'fixed slot' command.
The TX timer uses two registers (register addresses 0x04 and 0x05). Register 0x04 uses two bits (B7 and
B6) to define the trigger conditions. The remaining six bits of register 0x04 are upper bits and the eight bits
in register address 0x05 are lower bits that preset the counter. The range of this counter is from 590 ns to
9.7 ms, in 590-ns increments.
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5.11 Transmitter – External Power Amplifier / Subcarrier detector
The TRF7960A can be used in conjunction with an external TX power amplifier and/or external subcarrier
detector for the receiver path. If this is the case, certain registers must be programmed as shown here:
• Bit B6 of the Regulator and I/O Control register (0x0B) must be set to 1.
This setting has two functions: First, to provide a modulated signal for the transmitter, if needed.
Second, to configure the TRF7960A receiver inputs for an external demodulated subcarrier input.
• Bit B3 of the Modulation and SYS_CLK Control register (0x09) to 1 (see Section 6.1.2.8).
This function configures the ASK/OOK pin for either a digital or analog output (B3 = 0 enables a digital
output, and B3 = 1 enables an analog output). The design of an external power amplifier requires
detailed RF knowledge. There are also readily designed and certified high-power HF reader modules
on the market.
5.12 TRF7960A Communication Interface
5.12.1 General Introduction
The communication interface to the reader can be configured in two ways: with a eight line parallel
interface (D0:D7) plus DATA_CLK, or with a three or four wire Serial Peripheral Interface (SPI). The SPI
interface uses traditional Master Out/Slave In (MOSI), Master In, Slave Out (MISO), IRQ, and DATA_CLK
lines. The SPI can be operated with or without using the Slave Select line.
These communication modes are mutually exclusive; meaning, only one mode can be used at a time in
the application.
When the SPI interface is selected, the unused I/O_2, I/O_1, and I/O_0 pins must be hard-wired according
to Table 5-6. At power up, the TRF7960A IC samples the status of these three pins. If they are not the
same (all High or all Low) it enters one of the possible SPI modes.
The TRF7960A IC always behaves as the slave, while the microcontroller (MCU) behaves as the
masterdevice. The MCU initiates all communications with the TRF7960A IC. The TRF7960A IC makes
use of the Interrupt Request (IRQ) pin in both parallel and SPI modes to prompt the MCU for servicing
attention.
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Table 5-6. Pin Assignment in Parallel and Serial Interface Connection or Direct Mode
Pin
Parallel
DATA_ CLK
DATA_CLK
I/O_7
A/D[7]
I/O_6
A/D[6]
I/O_5 (3)
A/D[5]
(4)
SPI With SS
SPI Without SS
DATA_CLK from master
DATA_CLK from master
MOSI (1) = data in (reader in)
MOSI (1) = data in (reader in)
Direct mode, data out
(subcarrier or bit stream)
MISO (2) = data out (MCU out)
MISO (2) = data out (MCU out)
Direct mode, strobe (bit clock out)
See
(3)
SS (slave select)
See
(4)
(3)
–
I/O_4
A/D[4]
I/O_3
A/D[3]
–
–
–
I/O_2
A/D[2]
–
At VDD
At VDD
I/O_1
A/D[1]
–
At VDD
At VSS
I/O_0
A/D[0]
–
At VSS
At VSS
IRQ interrupt
IRQ interrupt
IRQ
(1)
(2)
(3)
Parallel Direct
DATA_CLK
IRQ interrupt IRQ interrupt
MOSI = Master Out, Slave In
MISO = Master In, Slave Out
The I/O_5 pin is used only for information when data is put out of the chip (for example, reading 1 byte from the chip). It is necessary
first to write in the address of the register (8 clocks) and then to generate another 8 clocks for reading out the data. The I/O_5 pin goes
high during the second 8 clocks. But for normal SPI operations I/O_5 pin is not used.
The slave select pin is active low.
Communication is initialized by a start condition, which is expected to be followed by an
Address/Command word (Adr/Cmd). The Adr/Cmd word is 8 bits long, and its format is shown in
Table 5-7.
Table 5-7. Address/Command Word Bit Distribution
Bit
Description
Bit Function
Address
Command
B7
Command control bit
0 = address
1 = command
0
1
B6
Read/Write
1 = read
0 = write
R/W
0
B5
Continuous address mode
1 = continuous mode
R/W
0
B4
Address/command bit 4
Adr 4
Cmd 4
B3
Address/command bit 3
Adr 3
Cmd 3
B2
Address/command bit 2
Adr 2
Cmd 2
B1
Address/command bit 1
Adr 1
Cmd 1
B0
Address/command bit 0
Adr 0
Cmd 0
The MSB (bit 7) determines if the word is to be used as a command or as an address. The last two
columns of Table 5-7 show the function of the separate bits if either address or command is written. Data
is expected once the address word is sent. In continuous address mode (continuous mode = 1), the first
data that follows the address is written (or read) to (from) the given address. For each additional data, the
address is incremented by one. Continuous mode can be used to write to a block of control registers in a
single stream without changing the address; for example, setup of the predefined standard control
registers from the MCU non-volatile memory to the reader. In non-continuous address mode (simple
addressed mode), only one data word is expected after the address.
Address Mode is used to write or read the configuration registers or the FIFO. When writing more than 12
bytes to the FIFO, the Continuous Address Mode should be set to 1.
The Command Mode is used to enter a command resulting in reader action (for example, initialize
transmission, enable reader, and turn reader on/off).
Examples of expected communications between an MCU and the TRF7960A are shown.
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Table 5-8. Continuous Address Mode
Start
Adr x
Data(x)
Data(x+1)
Data(x+2)
Data(x+3)
Data(x+4)
...
Data(x+n)
StopCont
Figure 5-5. Continuous Address Register Write Example Starting with Register 0x00 (Using SPI With SS
mode)
Figure 5-6. Continuous Address Register Read Example Starting with Register 0x00 (Using SPI With SS
Mode)
Table 5-9. Non-Continuous Address Mode (Single Address Mode)
Start
26
Adr x
Data(x)
Adr y
Data(y)
...
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Adr z
Data(z)
StopSgl
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Figure 5-7. Single Address Register Write Example of Register 0x00 (Using SPI With SS Mode)
Figure 5-8. Single Address Register Read Example of Register 0x00 (Using SPI With SS Mode)
Table 5-10. Direct Command Mode
Start
Cmd x
(Optional data or command)
Stop
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Figure 5-9. Direct Command Example of Sending 0x0F (Reset) (Using SPI With SS Mode)
The other Direct Command Codes from MCU to TRF7960A are described in Section 5.13.
5.12.2 FIFO Operation
The FIFO is a 12-byte register at address 0x1F with byte storage locations 0 to 11. FIFO data is loaded in
a cyclical manner and can be cleared by a reset command (0x0F, see graphic above showing this Direct
Command).
Associated with the FIFO are two counters and three FIFO status flags. The first counter is a 4-bit FIFO
byte counter (bits B0 to B3 in register 0x1C) that keeps track of the number of bytes loaded into the FIFO.
If the number of bytes in the FIFO is n, the register value is n – 1 (number of bytes in FIFO register). If 8
bytes are in the FIFO, the FIFO counter (bits B0 to B3 in register 0x1C) has the value 7.
A second counter (12 bits wide) indicates the number of bytes being transmitted (registers 0x1D and
0x1E) in a data frame. An extension to the transmission-byte counter is a 4-bit broken-byte counter also
provided in register 0x1E (bits B0 to B3). Together these counters make up the TX length value that
determines when the reader generates the EOF byte.
FIFO status flags are as follows:
1. FIFO overflow (bit B4 of register 0x1C): Indicates that the FIFO was loaded too soon
2. FIFO level too low (bit B5 of register 0x1C): Indicates that only three bytes are left to be transmitted
(Can be used during transmission.)
3. FIFO level high (bit B6 of register 0x1C): Indicates that nine bytes are already loaded into the FIFO
(Can be used during reception to generate a FIFO reception IRQ. This is to notify the MCU to service
the reader in time to ensure a continuous data stream.)
During transmission, the FIFO is checked for an almost-empty condition, and during reception for an
almost-full condition. The maximum number of bytes that can be loaded into the FIFO in a single
sequence is 12 bytes.
NOTE
The number of bytes in a frame, transmitted or received, can be greater than 12 bytes.
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During transmission, the MCU loads the TRF7960A FIFO (or, during reception, the MCU removes data
from the FIFO), and the FIFO counter counts the number of bytes being loaded into the FIFO. Meanwhile,
the byte counter keeps track of the number of bytes being transmitted. An interrupt request is generated if
the number of bytes in the FIFO is less than 3 or greater than 9, so that MCU can send new data or
remove the data as necessary. The MCU also checks the number of data bytes to be sent, so as to not
surpass the value defined in TX length bytes. The MCU also signals the transmit logic when the last byte
of data is sent or was removed from the FIFO during reception. Transmission starts automatically after the
first byte is written into FIFO.
Figure 5-10. Checking the FIFO Status Register (Using SPI With SS Mode)
5.12.3 Parallel Interface Mode
In parallel mode, the start condition is generated on the rising edge of the I/O_7 pin while the CLK is high.
This is used to reset the interface logic. Figure 5-11 shows the sequence of the data, with an 8-bit address
word first, followed by data.
Communication is ended by:
• The StopSmpl condition, where a falling edge on the I/O_7 pin is expected while CLK is high
• The StopCont condition, where the I/O_7 pin must have a successive rising and falling edge while CLK
is low in order to reset the parallel interface and be ready for the new communication sequence
• The StopSmpl condition is also used to terminate the Direct Mode.
Figure 5-11. Parallel Interface Communication With Simple Stop Condition (StopSmpl)
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Figure 5-12. Parallel Interface Communication With Continuous Stop Condition (StopCont)
Figure 5-13. Parallel Interface Communication With Continuous Stop Condition
5.12.3.1 Reception of Air Interface Data
At the start of a receive operation (when SOF is successfully detected), B6 is set in the IRQ Status
register. An interrupt request is sent to the MCU at the end of the receive operation if the receive data
string was shorter than or equal to 8 bytes. The MCU receives the interrupt request, then checks to
determine the reason for the interrupt by reading the IRQ Status register (address 0x0C), after which the
MCU reads the data from the FIFO.
If the received packet is longer than 8 bytes, the interrupt is sent before the end of the receive operation
when the ninth byte is loaded into the FIFO (75% full). The MCU should again read the content of the IRQ
Status register to determine the cause of the interrupt request. If the FIFO is 75% full (as marked with flag
B5 in IRQ Status register and by reading the FIFO Status register), the MCU should respond by reading
the data from FIFO to make room for new incoming receive data. When the receive operation is finished,
the interrupt is sent and the MCU must check how many words are still present in the FIFO before it
finishes reading.
If the reader detects a receive error, the corresponding error flag is set (framing error, CRC error) in the
IRQ Status register, indicating to the MCU that reception was not completed correctly.
5.12.3.2 Data Transmission to MCU
Before beginning data transmission, the FIFO should always be cleared with a reset command (0x0F).
Data transmission is initiated with a selected command (see Section 5.13). The MCU then commands the
reader to do a continuous write command (0x3D) (see Table 5-7) starting from register 0x1D. Data written
into register 0x1D is the TX length byte 1 (upper and middle nibbles), while the following byte in register
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0x1E is the TX length byte 2 (lower nibble and broken byte length). Note that the TX byte length
determines when the reader sends the EOF byte. After the TX length bytes are written, FIFO data is
loaded in register 0x1F with byte storage locations 0 to 11. Data transmission begins automatically after
the first byte is written into the FIFO. The loading of TX length bytes and the FIFO can be done with a
continuous write command, as the addresses are sequential.
At the start of transmission, the flag B7 (IRQ_TX) is set in the IRQ Status register. If the transmit data is
shorter than or equal to 4 bytes, the interrupt is sent only at the end of the transmit operation. If the
number of bytes to be transmitted is higher or equal to 5, then the interrupt is generated. This occurs also
when the number of bytes in the FIFO reaches 3. The MCU should check the IRQ Status register and
FIFO Status register and then load additional data to the FIFO, if needed. At the end of the transmit
operation, an interrupt is sent to inform the MCU that the task is complete.
5.12.4 Serial Interface Communication (SPI)
When an SPI interface is utilized, I/O pins, I/O_2, I/O_1, and I/O_0, must be hard wired according to
Table 5-7. On power up, the TRF7960A looks for the status of these pins; if they are not the same (not all
high, or not all low), the reader enters into one of two possible SPI modes:
• SPI with slave select
or
• SPI without slave select
The choice of one of these modes over the other should be made based on the available GPIOs and the
desired control of the system.
The serial communications work in the same manner as the parallel communications with respect to the
FIFO, except for the following condition. On receiving an IRQ from the reader, the MCU reads the
TRF7960A IRQ Status register to determine how to service the reader. After this, the MCU must to do a
dummy read to clear the reader's IRQ Status register. The dummy read is required in SPI mode, because
the reader's IRQ Status register needs an additional clock cycle to clear the register. This is not required
in parallel mode, because the additional clock cycle is included in the Stop condition.
A procedure for a dummy read is as follows:
1. Starting the dummy read
(a) When using slave select (SS): set SS bit low
(b) When not using SS: start condition is when SCLK is high
2. Send address word to IRQ Status register (0x0C) with read and continuous address mode bits set to 1
3. Read 1 byte (8 bits) from IRQ Status register (0x0C)
4. Dummy-read 1 byte from register 0Dh (collision position and interrupt mask)
5. Stopping the dummy read
(a) When using slave select (SS): set SS bit high
(b) When not using SS: stop condition when SCLK is high
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Write Address
Byte (0x6C)
Read Data in
IRQ Status Register
Dummy Read
DATA_CLK
MOSI
MISO
0
1
1
0
1
1
0
No Data Transitions
(All High/Low)
No Data Transitions
(All High/Low)
0
Ignore
B7 B6 B5 B4 B3 B2 B1 B0
Don't Care
SLAVE
SELECT
Figure 5-14. Procedure for Dummy Read
Figure 5-15. Dummy Read Using SPI With SS
5.12.4.1 Serial Interface Mode Without Slave Select (SS)
The serial interface without the slave select pin must use delimiters for the start and stop conditions.
Between these delimiters, the address, data, and command words can be transferred. All words must be 8
bits long with MSB transmitted first (see Figure 5-16).
Start
Condition
Stop
Condition
Data Clock
50 ns
Data In
b7
b6
b5
b4
b3
b2
b1
b0
Data Out
Figure 5-16. SPI Without Slave Select Timing
In this mode, a rising edge on data in (I/O_7, pin 24) while SCLK is high resets the serial interface and
prepares it to receive data. Data in can change only when SCLK is low, and it is read by the reader on the
SCLK rising edge. Communication is terminated by the stop condition when the data in falling edge occurs
during a high SCLK period.
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5.12.4.2 Serial Interface Mode With Slave Select (SS)
The serial interface is in reset while the Slave Select signal is high. Serial data in (MOSI) changes on the
falling edge, and is validated in the reader on the rising edge, as shown in Figure 5-17. Communication is
terminated when the Slave Select signal goes high.
All words must be 8 bits long with the MSB transmitted first.
tSTE,LEAD
Slave
Select
Write Mode
CKPH = 1, CKPL = 0
Data Transition is on
tSTE,LAG
Data Clock Falling Edge
MOSI Valid on Data Clock Rising Edge
Read Mode
CKPH = 0, CKPL = 0
Data Transition is on
tSTE,LAG
Data Clock Rising Edge
MOSI Valid on Data Clock Falling Edge
Switch
DATA_CLK
Polarity
1/fUCxCLK
Data
Clock
tLO/HI
tLO/HI
tSU,SO
tHD,SI
tSU,SI
MOSI
b7
No Data Transitions
(All High/Low)
b0
b6 to b1
tHD,SO
tVALID,SO
MISO
Don't Care
b7
b6...
...b1
tSTE,DIS
b0
Figure 5-17. SPI With Slave Select Timing
The read command is sent out on the MOSI pin, MSB first, in the first eight clock cycles. MOSI data
changes on the falling edge, and is validated in the reader on the rising edge, as shown in Figure 5-17.
During the write cycle, the serial data out (MISO) is not valid. After the last read command bit (B0) is
validated at the eighth rising edge of SCLK, after half a clock cycle, valid data can be read on the MISO
pin at the falling edge of SCLK. It takes eight clock edges to read out the full byte (MSB first).
When using the hardware SPI (for example, an MSP430 hardware SPI) to implement this feature, care
must be taken to switch the SCLK polarity after write phase for proper read operation. The example clock
polarity for the MSP430-specific environment is shown in the write-mode and read-mode boxes of
Figure 5-17. See the USART-SPI chapter for any specific microcontroller family for further information on
the setting the appropriate clock polarity. This clock polarity switch must be done for all read (single,
continuous) operations. The MOSI (serial data out) should not have any transitions (all high or all low)
during the read cycle. The Slave Select should be low during the whole write and read operation.
See Section 3.5, Switching Characteristics, for the timing values shown in Figure 5-17.
The continuous read operation is shown in Figure 5-18.
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Write
Address Byte
Read
Data Byte 1
B7 B6 B5 B4 B3 B2 B1 B0
No Data Transitions
(All High/Low)
Read
Data Byte n
DATA_CLK
MOSI
MISO
Don't Care
B7 B6 B5 B4 B3 B2 B1 B0
No Data Transitions
(All High/Low)
B7 B6 B5 B4 B3 B2 B1 B0
SLAVE
SELECT
Figure 5-18. Continuous Read Operation Using SPI With Slave Select
Figure 5-19. Continuous Read of Registers 0x00 Through 0x05 Using SPI With SS
Performing a Single Slot Inventory Command as an example is shown in Figure 5-20. Reader registers (in
this example) are configured for 5-VDC input and default operation. Full sequences for other settings and
protocols can be downloaded here: http://www.ti.com/lit/zip/sloc240.
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Figure 5-20. Inventory Command Sent From MCU to TRF7960A
The TRF7960A reads these bytes from the MCU and then sends out Request Flags, Inventory Command,
and Mask over the air to the ISO15693 transponder. After these three bytes have been transmitted, an
interrupt occurs from the reader to indicate back to the MCU that the transmission has been completed. In
the example shown in Figure 5-21, this IRQ occurs approximately 1.6 ms after the SS line goes high after
the Inventory command is sent out.
Figure 5-21. IRQ After Inventory Command
The IRQ Status register read (0x6C) yields 0x80, which indicates that TX is complete. This is followed by
dummy clock and reset of FIFO with dummy clock. Then, if a tag is in the field and no error is detected by
the reader, a second interrupt is expected and occurs (in this example) approximately 4 ms after first IRQ
is read and cleared.
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In the continuation of the example (see Figure 5-22), the IRQ Status register is read using method
previously recommended, followed by a single read of the FIFO Status register, which indicates that there
are at least 9 bytes to be read out.
Figure 5-22. IRQ Status Register Read Followed by FIFO Status Register Read
This is followed by a continuous read of the FIFO (see Figure 5-23). The first byte is 0x00 for no error.
The next byte is the DSFID (usually shipped by manufacturer as 0x00), then the UID, shown here up to
the next most significant byte, the MFG code (0x07 to indicate TI silicon).
Figure 5-23. Continuous Read of FIFO
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This is followed by another IRQ approximately 160 µs later, as there is still one byte in FIFO, the MSB of
the UID, which must be retrieved (see Figure 5-24). IRQ register read shows RX is complete and FIFO
register status shows one byte available, as expected and it is the E0, indicating ISO15693 transponder.
Figure 5-24. IRQ With One Byte in FIFO
At this time, the application should reset the FIFO and read out the RSSI value of the tag (see
Figure 5-25). In this case, the transponder is very close to the antenna, so value of 0x7E is recovered.
Figure 5-25. Reset FIFO and Read RSSI
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5.12.5 Direct Mode
Direct mode allows the reader to be configured in one of two ways.
Direct Mode 0 (bit 6 = 0, as defined in ISO Control register) allows the application to use only the
front-end functions of the reader, bypassing the protocol implementation in the reader. For transmit
functions, the application has direct access to the transmit modulator through the MOD pin (pin 14). On
the receive side, the application has direct access to the subcarrier signal (digitized RF envelope
signal) on I/O_6 (pin 23).
Direct Mode 1 (bit 6 = 1, as defined in ISO Control register) uses the subcarrier signal decoder of the
selected protocol (as defined in ISO Control register). This means that the receive output is not the
subcarrier signal but the decoded serial bit stream and bit clock signals. The serial data is available on
I/O_6 (pin 23), and the bit clock is available on I/O_5 (pin 22). The transmit side is identical; the
application has direct control over the RF modulation through the MOD input. This mode is provided so
that the application can implement a protocol that has the same bit coding as one of the protocols
implemented in the reader, but needs a different framing format.
To select Direct Mode, first choose which Direct Mode to enter by writing B6 in the ISO Control register.
This bit determines if the receive output is the direct subcarrier signal (B6 = 0) or the serial data of the
selected decoder. If B6 = 1, then the application must also define which protocol should be used for bit
decoding by writing the appropriate setting in the ISO Control register.
The reader actually enters the Direct Mode when B6 (direct) is set to 1 in the Chip Status Control register.
Direct mode starts immediately. The write command should not be terminated with a stop condition (see
communication protocol), because the stop condition terminates the Direct Mode and clears B6. This is
necessary as the Direct Mode uses one or two I/O pins (I/O_6 and I/O_5). Normal parallel communication
is not possible in Direct Mode. Sending a stop condition terminates Direct Mode.
Figure 5-26 shows the different configurations available in Direct Mode.
• In mode 0, the reader is used as an AFE only, and protocol handling is bypassed.
• In mode 1, framing is not done, but SOF and EOF are present. This allows for a user-selectable
framing level based on an existing ISO standard.
• In mode 2, data is ISO-standard formatted. SOF, EOF, and error checking are removed, so the
microprocessor receives only bytes of raw data via a 12-byte FIFO.
Analog Front End (AFE)
Direct Mode 0:
Raw RF Sub-Carrier
Data Stream
ISO Encoders/Decoders
14443A
14443B
15693
FeliCa
Direct Mode 1:
Raw Digital ISO Coded
Data Without
Protocol Frame
Packetization/Framing
Microcontroller
ISO Mode:
Full ISO Framing
and Error Checking
(Typical Mode)
Figure 5-26. User-Configurable Modes
The steps to enter Direct Mode are listed below, using SPI with SS communication method only as one
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example, as Direct Mode(s) are also possible with parallel and SPI without SS. The application must enter
Direct Mode 0 to accommodate non-ISO standard compliant card type communications. Direct Mode can
be entered at any time, so that if a card type started with ISO standard communications, then deviated
from the standard after being identified and selected, the ability to go into Direct Mode 0 becomes very
useful.
Step 1: Configure pins I/O_0 to I/O_2 for SPI with SS
Step 2: Set pin 12 of the TRF7960A (ASK/OOK pin) to 0 for ASK or 1 for OOK
Step 3: Program the TRF7960A registers
The following registers need to be explicitly set before going into Direct Mode.
1. ISO Control register (0x01) to the appropriate standard:
– 0x02 for ISO 15693 high data rate (26.48 kbps)
– 0x08 for ISO14443A (106 kbps)
– 0x1A for FeliCa 212 kbps
– 0x1B for FeliCa 424 kbps
2. Modulator and SYS_CLK Register (0x09) to the appropriate clock speed and modulation:
– 0x21 for 6.78-MHz clock and OOK (100%) modulation
– 0x20 for 6.78-MHz clock and ASK 10% modulation
– 0x22 for 6.78-MHz clock and ASK 7% modulation
– 0x23 for 6.78-MHz clock and ASK 8.5% modulation
– 0x24 for 6.78-MHz clock and ASK 13% modulation
– 0x25 for 6.78-MHz clock and ASK 16% modulation
See register 0x09 definition for all other possible values.
Example register setting for ISO14443A at 106 kbps:
– ISO Control register (0x01) to 0x08
– RX No Response Wait Time register (0x07) to 0x0E
– RX Wait Time register (0x08) to 0x07
– Modulator Control register (0x09) to 0x21 (or any custom modulation)
– RX Special Settings register (0x0A) to 0x20
Step 4: Enter Direct Mode
The following registers must be reprogrammed to enter Direct Mode:
a. Set bit B6 of the Modulator and SYS_CLK Control register (0x09) to 1.
b. Set bit B6 of the ISO Control register (0x01) to 0 for Direct Mode 0 (default its 0)
c. Set bit B6 of the Chip Status Control register (0x00) to 1 to enter Direct Mode (do not send a Stop
condition after this command)
NOTE
–
–
It is important that the last write be NOT terminated with Stop condition. For SPI, this
means that Slave Select (I/O_4) continues to stay low.
Sending a Stop condition terminates the Direct Mode and clears bit B6 in the Chip Status
Control register (0x00).
NOTE
Access to registers, FIFO, and IRQ is not available during Direct Mode 0.
Remember that the reader enters Direct Mode 0 when bit 6 of the Chip Status Control register (0x00) is
set to a 1, and it stays in Direct Mode 0 until a Stop condition is sent from the microcontroller.
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NOTE
The write command should not be terminated with a Stop condition (for example, in SPI
mode this is done by bringing the SS line high after the register write), because the Stop
condition terminates the Direct Mode and clears bit 6 of the Chip Status Control register
(0x00), making it a 0.
Figure 5-27. Entering Direct Mode 0
Step 5: Transmit data using Direct Mode
The user now has direct control over the RF modulation through the MOD input.
TRF796x
Microcontroller
MOD
(Pin 14)
Drive the MOD pin
according to the data-coding
specified by the standard
IO6
(Pin 23)
Decode the subcarrier
information according
to the standard
Figure 5-28. Control of RF Modulation Using MOD
The microcontroller is responsible for generating data according to the coding specified by the particular
standard. The microcontroller must generate SOF, EOF, data, and CRC. In Direct Mode, the FIFO is not
used and no IRQs are generated. See the applicable ISO standard to understand bit and frame
definitions.
Step 6: Receive data using Direct Mode
After the TX operation is complete, the tag responds to the request and the subcarrier data is available on
pin I/O_6. The microcontroller must decode the subcarrier signal according to the standard. This includes
decoding the SOF, data bits, CRC, and EOF. The CRC then must be checked to verify data integrity. The
receive data bytes must be buffered locally.
As an example of the receive data bits and framing level according to the ISO14443A standard is shown
in Figure 5-29 (taken from ISO14443 specification and TRF7960A air interface).
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?
?
?
128/fc = 9.435 µs = tb (106-kbps data rate)
64/fc = 4.719 µs = tx time
32/fc = 2.359 µs = t1 time
tb = 9.44 µs
tx = 4.72 µs
Sequence Y = Carrier for 9.44 µs
t1 = 2.48 µs
Sequence Z = Pause for 2 to 3 µs,
Carrier for Remainder of 9.44 µs
Figure 5-29. Receive Data Bits and Framing Level (ISO14443A)
Step 7: Exit Direct Mode 0
When an EOF is received, data transmission is over, and Direct Mode 0 can be terminated by sending a
Stop condition (the SS signal goes high). The TRF7960 returns to ISO Mode (normal mode).
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5.13 Direct Commands from MCU to Reader
5.13.1 Command Codes
Table 5-11 lists the valid commands that the MCU can send to the reader.
Table 5-11. Command Codes
Command
Code
Command
Comments
0x00
Idle
0x03
Software Initialization
0x0F
Reset
0x10
Transmission without CRC
0x11
Transmission with CRC
0x12
Delayed Transmission without CRC
0x13
Delayed Transmission with CRC
0x14
End of Frame/Transmit Next Time Slot
0x16
Block Receiver
0x17
Enable Receiver
0x18
Test external RF (RSSI at RX input with TX on)
0x19
Test internal RF (RSSI at RX input with TX off)
0x1A
Receiver Gain Adjust
Same as power on reset
ISO15693
The command code values from Table 5-11 are substituted in Table 5-12, Bits 0 through 4. Also, the
most-significant bit (MSB) in Table 5-12 must be set to 1.
Table 5-12. Address/Command Word Bit Distribution
Bit
Description
Bit Function
Address
Command
B7
Command control bit
0 = address
1 = command
0
1
B6
Read/Write
0 = write
1 = read
R/W
0
B5
Continuous address mode
Continuous
mode
Not used
B4
Address/Command bit 4
Adr 4
Cmd 4
B3
Address/Command bit 3
Adr 3
Cmd 3
B2
Address/Command bit 2
Adr 2
Cmd 2
B1
Address/Command bit 1
Adr 1
Cmd 1
B0
Address/Command bit 0
Adr 0
Cmd 0
The MSB determines if the word is to be used as a command or address. The last two columns of
Table 5-12 show the function of separate bits depending on whether address or command is written.
Command mode is used to enter a command resulting in reader action (for example, initialize
transmission, enable reader, or turn the reader on or off).
5.13.2 Reset (0x0F)
The reset command clears the FIFO contents and FIFO Status register (0x1C). It also clears the register
storing the collision error location (0x0E).
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5.13.3 Transmission With CRC (0x11)
The transmission command must be sent first, followed by transmission length bytes, and FIFO data. The
reader starts transmitting after the first byte is loaded into the FIFO. The CRC byte is included in the
transmitted sequence.
5.13.4 Transmission Without CRC (0x10)
The transmission command must be sent first, followed by transmission length bytes, and FIFO data. The
reader starts transmitting after the first byte is loaded into the FIFO. This is the same as the previous
section (Section 5.13.3), except that the CRC is not included.
5.13.5 Delayed Transmission With CRC (0x13)
The transmission command must be sent first, followed by the transmission length bytes, and FIFO data.
The reader transmission is triggered by the TX timer.
5.13.6 Delayed Transmission Without CRC (0x12)
The transmission command must be sent first, followed by the transmission length bytes, and FIFO data.
The reader transmission is triggered by the TX timer. This is the same as the previous section
(Section 5.13.5), except that the CRC is not included.
5.13.7 Transmit Next Time Slot (0x14)
When this command is received, the reader transmits the next slot command. The next slot sign is defined
by the protocol selection.
5.13.8 Block Receiver (0x16)
The block receiver command puts the digital part of receiver (bit decoder and framer) in reset mode. This
is useful in an extremely noisy environment, where the noise level could otherwise cause a constant
switching of the subcarrier input of the digital part of the receiver. The receiver (if not in reset) would try to
catch a SOF signal, and if the noise pattern matched the SOF pattern, an interrupt would be generated,
falsely signaling the start of an receive operation. A constant flow of interrupt requests can be a problem
for the external system (MCU), so the external system can stop this by putting the receive decoders in
reset mode.
The reset mode can be terminated in two ways:
The external system can send the enable receiver command (see Section 5.13.9).
The reset mode is automatically terminated at the end of a transmit operation.
The receiver can stay in reset after end of transmit if the RX Wait Time register (0x08) is set. In this case,
the receiver is enabled at the end of the wait time following the transmit operation.
5.13.9 Enable Receiver (0x17)
This command clears the reset mode in the digital part of the receiver if the reset mode was entered by
the block receiver command.
5.13.10 Test Internal RF (RSSI at RX Input With TX On) (0x18)
The level of the RF carrier at RF_IN1 and RF_IN2 inputs is measured. Operating range between 300 mVP
and 2.1 VP (step size is 300 mV). The two values are reported in the RSSI Levels register (0x0F). The
command is intended for diagnostic purposes to set correct RF_IN levels. Optimum RFIN input level is
approximately 1.6 VP or code 5 to 6. The nominal relationship between the RF peak level and RSSI code
is described in Table 5-13 and in Section 5.7.1.1.
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NOTE
If the command is executed immediately after power-up and before any communication with
tag was performed, the command must be preceded by the Enable RX command. The
Check RF commands require full operation, so the receiver must be activated by enable
receive or by a normal tag communication for the Check RF command to work properly.
Table 5-13. Test Internal RF
RF_IN1 (mVP):
300
600
900
1200
1500
1800
Decimal Code:
1
2
3
4
5
6
7
001
010
011
001
101
011
111
Binary Code:
2100
5.13.11 Test External RF (RSSI at RX Input With TX Off) (0x19)
This command can be used in active mode when the RF receiver is on but RF output is off. This means
bit B1 = 1 in the Chip Status Control register. The level of RF signal received on the antenna is measured
and reported in the RSSI Levels register (0x0F). The relation between the 3-bit code and the external RF
field strength [A/m] must be determinate by calculation or by experiments for each antenna type, because
the antenna Q and connection to the RF input influence the result. The nominal relation between the RF
peak to peak voltage in the RF_IN1 input and RSSI code is shown in Table 5-14 and in Section 5.7.1.2.
NOTE
If the command is executed immediately after power-up and before any communication with
tag was performed, the command must be preceded by the Enable RX command. The
Check RF commands require full operation, so the receiver must be activated by enable RX
or by a normal tag communication for the Check RF command to work properly.
Table 5-14. Test External RF
RF_IN1 (mVP):
40
60
80
100
140
180
Decimal Code:
1
2
3
4
5
6
7
001
010
011
001
101
011
111
Binary Code:
300
5.13.12 Receiver Gain Adjust (0x1A)
This command should be executed when the MCU determines that no tag response is detected and when
the RF and receivers are on. When this command is received, the reader observes the digitized receiver
output. If more than two edges are observed in 100 ms, the window comparator voltage is increased. The
procedure is repeated until the number of edges (changes of logical state) of the digitized reception signal
is less than 2 (in 100 ms). The command can reduce the input sensitivity in 5-dB increments up to 15 dB.
This command ensures better operation in a noisy environment. The gain setting is reset to maximum gain
at EN = 0, POR = 1.
5.13.13 Register Preset
After power-up and the EN pin low-to-high transition, the reader is in the default mode. The default
configuration is ISO15693, single subcarrier, high data rate, 1-out-of-4 operation. The low-level option
registers (0x02 to 0x0B) are automatically set to adapt the circuitry optimally to the appropriate protocol
parameters. When entering another protocol (by writing to the ISO Control register), the low-level option
registers are automatically configured to the new protocol parameters. After selecting the protocol, it is
possible to change some low-level register contents if needed. However, changing to another protocol and
then back reloads the default settings; then the custom settings must be reloaded.
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The Clo0 and Clo1 bits in the Modulator and SYS_CLK Control register (0x09), which define the
microcontroller frequency available on the SYS_CLK pin, are the only two bits in the configuration
registers that are not cleared during protocol selection.
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6 Register Description
6.1
Register Overview
Table 6-1 lists the registers available in the TRF7960A. These registers are described in the following
sections.
Table 6-1. Register Overview
Address
(hex)
Register
Read/Write
Main Control Registers
0x00
Chip status control
R/W
0x01
ISO control
R/W
Protocol Sub-Setting Registers
0x02
ISO14443B TX options
R/W
0x03
ISO 14443A high bit rate options
R/W
0x04
TX timer setting, H-byte
R/W
0x05
TX timer setting, L-byte
R/W
0x06
TX pulse-length control
R/W
0x07
RX no response wait
R/W
0x08
RX wait time
R/W
0x09
Modulator and SYS_CLK control
R/W
0x0A
RX special setting
R/W
0x0B
Regulator and I/O control
R/W
Status Registers
0x0C
IRQ status
0x0D
Collision position and interrupt mask register
R
0x0E
Collision position
R
0x0F
RSSI levels and oscillator status
R
0x1A
Test Register. Preset 0x00
R/W
0x1B
Test Register. Preset 0x00
R/W
0x1C
FIFO status
0x1D
TX length byte1
R/W
0x1E
TX length byte2
R/W
0x1F
FIFO I/O register
R/W
R/W
FIFO Registers
46
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6.1.1
Main Configuration Registers
6.1.1.1
Chip Status Control Register (0x00)
Table 6-2. Chip Status Control Register (0x00)
Function: Control of power mode, RF on/off, AGC, AM/PM, Direct Mode
Default Settings: Register default is 0x01. It is preset at EN = L or POR = H
Bit No.
Bit Name
B7
stby
B6
B5
B4
B3
Function
1 = Standby Mode
Standby mode keeps all supply regulators and the 13.56-MHz SYS_CLK
oscillator running (typical start-up time to full operation is 100 µs).
0 = Active Mode
Active Mode (default)
1 = Direct Mode 0/1
Provides user direct access to AFE (Direct Mode 0) or allows user to add
their own framing (Direct Mode 1). Bit 6 of ISO Control register must be set
by user before entering Direct Mode 0 or 1.
0 = ISO Mode (default)
Uses SPI or parallel communication with automatic framing and ISO
decoders
1 = RF output active
Transmitter on, receivers on
0 = RF output not active
Transmitter off
1 = half output power
TX_OUT (pin 5) = 8-Ω output impedance P = 100 mW (20 dBm) at 5 V,
P = 33 mW (+15 dBm) at 3.3 V
0 = full output power
TX_OUT (pin 5) = 4-Ω output impedance P = 200 mW (23 dBm) at 5V,
P = 70 mW (+18 dBm) at 3.3 V
1 = selects Main RX
input
RX_IN1 input is used
direct
rf_on
rf_pwr
pm_on
Description
0 = selects Aux RX input RX_IN2 input is used
B2
B1
agc_on
rec_on
1 = AGC on
Enables AGC (AGC gain can be set in register 0x0A)
0 = AGC off
AGC block is disabled
1 = receiver activated for
Forces enabling of receiver and TX oscillator. Used for external field
external field
measurement.
measurement
0 = automatic enable
B0
vrs5_3
1 = 5 V operation
0 = 3 V operation
Allows enable of the receiver via bit 5 of this register
Selects the VIN voltage range
Register Description
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ISO Control Register (0x01)
Table 6-3. ISO Control Register (0x01)
Function: Controls the selection of ISO standard protocol, Direct Mode, and receive CRC
Default Settings: Register default is 0x02 (ISO15693 high bit rate, one subcarrier, 1 out of 4). It is preset at EN = L or POR = H.
Bit No.
Bit Name
Function
Description
B7
rx_crc_n
CRC receive selection
1 = no RX CRC (CRC not present in the response)
0 = RX CRC (CRC is present in the response)
B6
dir_mode
Direct mode type
selection
0 = Direct Mode 0
1 = Direct Mode 1
B5
rfid
RFID / Reserved
0 = RFID mode
1 = Reserved (should be set to 0)
B4
iso_4
RFID
B3
iso_3
RFID
B2
iso_2
RFID
B1
iso_1
RFID
B0
iso_0
RFID
See Table 6-4 for B0:B4 settings based on ISO protocol desired by
application
Table 6-4. ISO Control Register: ISO_4 to ISO_0
ISO_4
ISO_3
ISO_2
ISO_1
ISO_0
0
0
0
0
0
ISO15693 low bit rate, 6.62 kbps, one subcarrier, 1 out of 4
0
0
0
0
1
ISO15693 low bit rate, 6.62 kbps, one subcarrier, 1 out of 256
0
0
0
1
0
ISO15693 high bit rate, 26.48 kbps, one subcarrier, 1 out of 4
0
0
0
1
1
ISO15693 high bit rate, 26.48 kbps, one subcarrier, 1 out of 256
0
0
1
0
0
ISO15693 low bit rate, 6.67 kbps, double subcarrier, 1 out of 4
0
0
1
0
1
ISO15693 low bit rate, 6.67 kbps, double subcarrier, 1 out of 256
0
0
1
1
0
ISO15693 high bit rate, 26.69 kbps, double subcarrier, 1 out of 4
0
0
1
1
1
ISO15693 high bit rate, 26.69 kbps, double subcarrier, 1 out of 256
0
1
0
0
0
ISO14443A RX bit rate, 106 kbps
0
1
0
0
1
ISO14443A RX high bit rate, 212 kbps
0
1
0
1
0
ISO14443A RX high bit rate, 424 kbps
0
1
0
1
1
ISO14443A RX high bit rate, 848 kbps
0
1
1
0
0
ISO14443B RX bit rate, 106 kbps
0
1
1
0
1
ISO14443B RX high bit rate, 212 kbps
0
1
1
1
0
ISO14443B RX high bit rate, 424 kbps
0
1
1
1
1
ISO14443B RX high bit rate, 848 kbps
1
1
0
1
0
FeliCa 212 kbps
1
1
0
1
1
FeliCa 424 kbps
(1)
48
Protocol
Remarks
Default for reader
RX bit rate (1)
RX bit rate (1)
For ISO14443A/B, when bit rate of TX is different than RX, settings can be done in REG (0x02 or 0x03)
Register Description
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6.1.2
Protocol Sub-Setting Registers
6.1.2.1
ISO14443B TX Options Register (0x02)
Table 6-5. ISO14443B TX Options Register (0x02)
Function: Selects the ISO subsets for ISO14443B – TX
Default Settings: 0x00 at POR = H or EN = L
Bit No.
Bit Name
B7
egt2
TX EGT time select MSB
B6
egt1
TX EGT time select
B5
egt0
TX EGT time select LSB
B4
eof_l0
1 = EOF → 0 length 11 etu
0 = EOF → 0 length 10 etu
B3
sof_l1
1 = SOF → 1 length 03 etu
0 = SOF → 1 length 02 etu
B2
sof _l0
1 = SOF → 0 length 11 etu
0 = SOF → 0 length 10 etu
B1
l_egt
B0
Unused
6.1.2.2
Function
Description
Three bit code defines the number of etu (0-7) which separate two
characters. ISO14443B TX only.
ISO14443B TX only
1 = EGT after each byte
0 = EGT after last byte is omitted
ISO 14443A High-Bit-Rate and Parity Options Register (0x03)
Table 6-6. ISO 14443A High-Bit-Rate and Parity Options Register (0x03)
Function: Selects the ISO subsets for ISO14443A – TX
Default Settings: 0x00 at POR = H or EN = L, and at each write to ISO Control register
Bit No.
Bit Name
Function
Description
TX bit rate different than RX bit
rate enable
Valid for ISO14443A/B high bit rate
TX bit rate
tx_br1 = 0, tx_br = 0: 106 kbps
tx_br1 = 0, tx_br = 1: 212 kbps
tx_br1 = 1, tx_br = 0: 424 kbps
tx_br1 = 1, tx_br = 1: 848 kbps
For 14443A high bit rate coding and decoding
B7
dif_tx_br
B6
tx_br1
B5
tx_br0
B4
parity-2tx
1 = parity odd except last byte,
which is even for TX
B3
parity-2rx
1 = parity odd except last byte,
which is even for RX
B2
Unused
B1
Unused
B0
Unused
Register Description
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TX Timer High Byte Control Register (0x04)
Table 6-7. TX Timer High Byte Control Register (0x04)
Function: For timings
Default Settings: 0xC2 at POR = H or EN = L, and at each write to ISO Control register
Bit No.
Bit Name
B7
tm_st1
Timer Start Condition
B6
tm_st0
Timer Start Condition
B5
tm_lengthD
Timer Length MSB
B4
tm_lengthC
Timer Length
B3
tm_lengthB
Timer Length
B2
tm_lengthA
Timer Length
B1
tm_length9
Timer Length
B0
tm_length8
Timer Length LSB
6.1.2.4
Function
Description
tm_st1
tm_st1
tm_st1
tm_st1
= 0, tm_st0
= 0, tm_st0
= 1, tm_st0
= 1, tm_st0
= 0: beginning of TX SOF
= 1: end of TX SOF
= 0: beginning of RX SOF
= 1: end of RX SOF
See Table 6-8 for Timer Length description
TX Timer Low Byte Control Register (0x05)
Table 6-8. TX Timer Low Byte Control Register (0x05)
Function: For timings
Default Settings: 0x00 at POR = H or EN = L, and at each write to ISO Control register
50
Bit No.
Bit Name
Function
B7
tm_length7
Timer Length MSB
B6
tm_length6
Timer Length
B5
tm_length5
Timer Length
B4
tm_length4
Timer Length
B3
tm_length3
Timer Length
B2
tm_length2
Timer Length
B1
tm_length1
Timer Length
B0
tm_length0
Timer Length LSB
Description
Defines the time when delayed transmission is started.
RX wait range is 590 ns to 9.76 ms (1 to 16383)
Step size is 590 ns
All bits low = timer disabled (0x00)
Preset 0x00 for all other protocols
Register Description
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6.1.2.5
TX Pulse Length Control Register (0x06)
The length of the modulation pulse is defined by the protocol selected in the ISO Control register (0x01).
With a high-Q antenna, the modulation pulse is typically prolonged, and the tag detects a longer pulse
than intended. For such cases, the modulation pulse length can be corrected by using the TX pulse length
register 0x06. If the register contains all zeros, then the pulse length is governed by the protocol selection.
If the register contains a value other than 0x00, the pulse length is equal to the value of the register in
73.7-ns increments. This means the range of adjustment can be 73.7 ns to 18.8 µs.
Table 6-9. TX Pulse Length Control Register (0x06)
Function: Controls the length of TX pulse
Default Settings: Register default is set to 0x00 at POR = H or EN = L and at each write to ISO Control register.
Bit No.
Bit Name
B7
Pul_p2
B6
Pul_p1
B5
Pul_p0
B4
Pul_c4
B3
Pul_c3
B2
Pul_c2
B1
Pul_c1
B0
Pul_c0
6.1.2.6
Function
Description
Pulse length MSB
The pulse range is 73.7 ns to 18.8 µs (1 to 255), step size 73.7 ns
All bits low (00): pulse length control is disabled
The following default timings are preset by the ISO Control register (0x01):
9.44 µs → ISO15693 (TI Tag-It HF-I)
2.36 µs → ISO14443A at 106 kbps
1.4 µs → ISO14443A at 212 kbps
737 ns → ISO14443A at 424 kbps
442 ns → ISO14443A at 848 kbps; pulse length control disabled
Pulse length LSB
RX No Response Wait Time Register (0x07)
The RX no response timer is controlled by the RX No Response Wait Time register. This timer measures
the time from the start of slot in the anti-collision sequence until the start of tag response. If there is no tag
response in the defined time, an interrupt request is sent and a flag is set in IRQ Status Control register
(0x0C). This enables the external controller to be relieved of the task of detecting empty slots. The wait
time is stored in the register in increments of 37.76 µs. This register is also preset, automatically, for every
new protocol selection.
Table 6-10. RX No Response Wait Time Register (0x07)
Function: Defines the time when "no response" interrupt is sent; only for ISO15693
Default Settings: Default is set to 0x0E at POR = H or EN = L and at each write to ISO Control register.
Bit No.
Bit Name
B7
NoResp7
B6
NoResp6
B5
NoResp5
B4
NoResp4
B3
NoResp3
B2
NoResp2
B1
NoResp1
B0
NoResp0
Function
Description
No response MSB
Defines the time when no response interrupt is sent. It starts from the end of
TX EOF. RX no response wait range is 37.76 µs to 9628 µs (1 to 255). Step
size is 37.76 µs.
The following default timings are preset by the ISO Control register (0x01):
529 µs → for all protocols that are supported but not listed here
755 µs → ISO15693 high data rate (TI Tag-It HF-I)
1812 µs → ISO15693 low data rate (TI Tag-It HF-I)
No response LSB
Register Description
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RX Wait Time Register (0x08)
The RX wait time timer is controlled by the value in the RX Wait Time register. This timer defines the time
after the end of the transmit operation in which the receive decoders are not active (held in reset state).
This prevents incorrect detections resulting from transients following the transmit operation. The value of
the RX wait time register defines this time in increments of 9.44 µs. This register is preset at every write to
ISO Control register according to the minimum tag response time defined by each standard.
Table 6-11. RX Wait Time Register (0x08)
Function: Defines the time after TX EOF when the RX input is disregarded; for example, to block out electromagnetic disturbance
generated by the responding card.
Default Settings: Register default is set to 0x1F at POR = H or EN = L and at each write to the ISO control register.
52
Bit No.
Bit Name
B7
Rxw7
B6
Rxw6
B5
Rxw5
B4
Rxw4
B3
Rxw3
B2
Rxw2
B1
Rxw1
B1
Rxw0
Function
RX wait time
Description
Defines the time after the TX EOF during which the RX input is ignored.
Time starts from the end of TX EOF.
RX wait range is 9.44 µs to 2407 µs (1 to 255). Step size is: 9.44 µs.
The following default timings are preset by the ISO Control register (0x01):
9.44 µs → FeliCa
66 µs → ISO14443A and B
293 µs → ISO15693 (TI Tag-It HF-I)
Register Description
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6.1.2.8
Modulator and SYS_CLK Control Register (0x09)
The frequency of SYS_CLK (pin 27) is programmable by the bits B4 and B5 of this register. The frequency
of the TRF7960A system clock oscillator is divided by 1, 2 or 4 resulting in available SYS_CLK
frequencies of 13.56 MHz or 6.78 MHz or 3.39 MHz.
The ASK modulation depth is controlled by bits B0, B1 and B2. The range of ASK modulation is 7% to
30% or 100% (OOK). The selection between ASK and OOK (100%) modulation can also be done using
direct input OOK (pin 12). The direct control of OOK/ASK using OOK pin is only possible if the function is
enabled by setting B6 = 1 (en_ook_p) in this register (0x09) and the ISO Control register (0x01, B6 = 1).
When configured this way, the MOD (pin 14) is used as input for the modulation signal.
Table 6-12. Modulator and SYS_CLK Control Register (0x09)
Function: Controls the modulation input and depth, ASK / OOK control and clock output to an external system (an MCU)
Default Settings: Register default is set to 0x11 at POR = H or EN = L, and at each write to the ISO Control register, except Clo1 and
Clo0.
Bit No.
Bit Name
B7
Unused
Function
B6
en_ook_p
1 = enables external selection of
ASK or OOK modulation
0 = default operation as defined
in bits B0 to B2 of this register
B5
Clo1
SYS_CLK output frequency MSB
B4
Clo0
B3
en_ana
B2
B1
B0
Pm2
Pm1
Pm0
SYS_CLK output frequency LSB
Description
Enable ASK/OOK pin (pin 12) for "on the fly change" between any
pre-selected ASK modulation as defined by B0 to B2 and OOK
modulation.
If B6 is set to 1, pin 12 is configured as follows:
1 = OOK modulation
0 = Modulation as defined in B0 to B2 (0x09)
Clo1
Clo0
0
0
SYS_CLK Output
Disabled
0
1
3.39 MHz
1
0
6.78 MHz
1
1
13.56 MHz
1 = sets pin 12 (ASK/OOK) as an For test and measurement purpose. ASK/OOK pin 12 can be used
analog output
to monitor the analog subcarrier signal before the digitizing with DC
0 = default
level equal to AGND.
Modulation depth MSB
Modulation depth
Modulation depth LSB
Pm2
Pm1
Pm0
Modulation Type and Percentage
0
0
0
ASK 10%
0
0
1
OOK (100%)
0
1
0
ASK 7%
0
1
1
ASK 8.5%
1
0
0
ASK 13%
1
0
1
ASK 16%
1
1
0
ASK 22%
1
1
1
ASK 30%
Register Description
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RX Special Setting Register (0x0A)
Table 6-13. RX Special Setting Register (0x0A)
Function: Sets the gains and filters directly
Default Settings: Register default is set to 0x40 at POR = H or EN = L, and at each write to the ISO Control register (0x01).When bits B7,
B6, B5 and B4 are all zero, the filters are set for ISO14443B (240 kHz to 1.4 MHz).
Bit No.
Bit Name
B7
C212
Bandpass 110 kHz to 570 kHz
Function
Appropriate for 212-kHz subcarrier system (FeliCa)
B6
C424
Bandpass 200 kHz to 900 kHz
Appropriate for 424-kHz subcarrier used in ISO15693
B5
M848
Bandpass 450 kHz to 1.5 MHz
Appropriate for Manchester-coded 848-kHz subcarrier used in
ISO14443A
B4
hbt
Bandpass 100 kHz to 1.5 MHz
Gain reduced for 18 dB
Appropriate for highest bit rate (848 kbps) used in high-bit-rate
ISO14443
B3
gd1
B2
gd2
00
01
10
11
Sets the RX gain reduction and reduces sensitivity
B1
agcr
B0
no-lim
= gain reduction 0 dB
= gain reduction for 5 dB
= gain reduction for 10 dB
= gain reduction for 15 dB
Description
AGC activation level change
AGC activation level changed from five times the digitizing level to
three times the digitizing level.
1 = 3x
0 = 5x
AGC action is not limited in time
AGC action can be done any time during receive process. It is not
limited to the start of receive ("max hold").
1 = continuously, no time limit
0 = 8 subcarrier pulses
The first four steps of the AGC control are comparator adjustment. The second three steps are gain
reduction done automatically by AGC control. The AGC is turned on after TX.
The first gain and filtering stage following the RF envelope detector has a nominal gain of 15, and the
3-dB band-pass frequencies are adjustable in the range from 100 kHz to 400 kHz for high pass and 600
kHz to 1.5 MHz for low pass. The next gain and filtering stage has a nominal gain of 8, and the frequency
characteristic identical to first stage. The filter setting is done automatically with internal preset for each
new selection of communication standard in the ISO Control register. Additional corrections can be done
by directly writing into the RX Special Setting register.
The second receiver gain stage and digitizer stage are included in the AGC loop. The AGC loop can be
activated by setting the bit B2 = 1 (agc-on) in the Chip Status Control register. If activated the AGC
monitors the signal level at the input of digitizing stage. If the signal level is significantly higher than the
digitizing threshold level, the gain reduction is activated. The signal level, at which the action is started, is
by default five times the digitizing threshold level. It can be reduced to three times the digitizing level by
setting bit B1 = 1 (agcr) in the RX Special Setting register.
The AGC action typically finishes after four subcarrier pulses. By default, the AGC action is blocked after
first few pulses of subcarrier signal so AGC cannot interfere with signal reception during rest of data
packet. In certain cases, this is not optimal, so this blocking can be removed by setting B0 = 1 (no_lim) in
the RX Special Setting register.
NOTE
The setting of bits b4, b5, b6, and b7 to zero selects bandpass characteristic of 240 kHz to
1.4 MHz. This is appropriate for ISO14443B, FeliCa protocol, and ISO14443A higher bit
rates 212 kbps and 424 kbps.
54
Register Description
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6.1.2.10 Regulator and I/O Control Register (0x0B)
Table 6-14. Regulator and I/O Control Register (0x0B)
Function: Control the three voltage regulators
Default Settings: Register default is set to 0x87 at POR = H or EN = L
Bit No.
Bit Name
B7
auto_reg
Function
Description
Automatic system settings:
VDD_RF = VIN – 250 mV
VDD_A = VIN – 250 mV
VDD_X = VIN – 250 mV, but not higher than 3.4 V
0 = Manual system
1 = Automatic system
Manual system settings:
See B2 to B0
B6
en_ext_pa
Support for external power
amplifier
Internal peak detectors are disabled, receiver inputs (RX_IN1 and
RX_IN2) accept externally demodulated subcarrier. At the same
time, the ASK/OOK pin becomes modulation output for external TX
amplifier.
B5
io_low
1 = Enable low peripheral
communication voltage
When B5 = 1, maintains the output driving capabilities of the I/O
pins connected to the level shifter under low-voltage operation.
Should be set 1 when VDD_I/O voltage is between 1.8 V and 2.7 V.
B4
Unused
No function
Default is 0.
B3
Unused
No function
Default is 0.
B2
vrs2
B1
vrs1
B0
vrs0
Voltage set MSB
vrs3_5 = L:
VDD_RF, VDD_A, VDD_X range 2.7 V to 3.4 V.
See Table 6-15 through Table 6-18.
Voltage set LSB
Table 6-15. Supply Regulator Setting, Manual 5-V System
Register
Option Bits Setting in Control Register
B7
B6
B5
B4
B3
B2
B1
00
Action
B0
1
5-V system
0B
0
Manual regulator setting
0B
0
1
1
1
VDD_RF = 5 V, VDD_A = 3.5 V, VDD_X = 3.4 V
0B
0
1
1
0
VDD_RF = 4.9 V, VDD_A = 3.5 V, VDD_X = 3.4 V
0B
0
1
0
1
VDD_RF = 4.8 V, VDD_A = 3.5 V, VDD_X = 3.4 V
0B
0
1
0
0
VDD_RF = 4.7 V, VDD_A = 3.5 V, VDD_X = 3.4 V
0B
0
0
1
1
VDD_RF = 4.6 V, VDD_A = 3.5 V, VDD_X = 3.4 V
0B
0
0
1
0
VDD_RF = 4.5 V, VDD_A = 3.5 V, VDD_X = 3.4 V
0B
0
0
0
1
VDD_RF = 4.4 V, VDD_A = 3.5 V, VDD_X = 3.4 V
0B
0
0
0
0
VDD_RF = 4.3 V, VDD_A = 3.5 V, VDD_X = 3.4 V
Register Description
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Table 6-16. Supply Regulator Setting, Manual 3-V System
Register
Option Bits Setting in Control Register
B7
B6
B5
B4
B3
B2
B1
00
Action
B0
0
3-V system
0B
0
Manual regulator setting
0B
0
1
1
1
VDD_RF = 3.4 V, VDD_A = 3.4 V, VDD_X = 3.4 V
0B
0
1
1
0
VDD_RF = 3.3 V, VDD_A = 3.3 V, VDD_X = 3.3 V
0B
0
1
0
1
VDD_RF = 3.2 V, VDD_A = 3.2 V, VDD_X = 3.2 V
0B
0
1
0
0
VDD_RF = 3.1 V, VDD_A = 3.1 V, VDD_X = 3.1 V
0B
0
0
1
1
VDD_RF = 3.0 V, VDD_A = 3.0 V, VDD_X = 3.0 V
0B
0
0
1
0
VDD_RF = 2.9 V, VDD_A = 2.9 V, VDD_X = 2.9 V
0B
0
0
0
1
VDD_RF = 2.8 V, VDD_A = 2.8 V, VDD_X = 2.8 V
0B
0
0
0
0
VDD_RF = 2.7 V, VDD_A = 2.7 V, VDD_X = 2.7 V
Table 6-17. Supply Regulator Setting, Automatic 5-V System
Register
Option Bits Setting in Control Register
B7
B6
B5
B4
B3
B2 (1)
B1
00
(1)
Action
B0
1
5-V system
0B
1
x
1
1
Automatic regulator setting 250-mV difference
0B
1
x
1
0
Automatic regulator setting 350-mV difference
0B
1
x
0
0
Automatic regulator setting 400-mV difference
x = don't care
Table 6-18. Supply Regulator Setting, Automatic 3-V System
Register
Option Bits Setting in Control Register
B7
B6
B5
B4
B3
B2 (1)
B1
00
(1)
56
Action
B0
0
3-V system
0B
1
x
1
1
Automatic regulator setting 250-mV difference
0B
1
x
1
0
Automatic regulator setting 350-mV difference
0B
1
x
0
0
Automatic regulator setting 400-mV difference
x = don't care
Register Description
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6.1.3
Status Registers
6.1.3.1
IRQ Status Register (0x0C)
Table 6-19. IRQ Status Register (0x0C)
Function: Information available about TRF7960A IRQ and TX/RX status
Default Settings: Register default is set to 0x00 at POR = H or EN = L, and at each write to the ISO Control Register 0x01. It is also
automatically reset at the end of a read phase. The reset also removes the IRQ flag.
Bit No.
Bit Name
Function
Description
B7
Irq_tx
IRQ set due to end of TX
Signals that TX is in progress. The flag is set at the start of TX but
the interrupt request (IRQ=1) is sent when TX is finished.
B6
Irg_srx
IRQ set due to RX start
Signals that RX SOF was received and RX is in progress. The flag
is set at the start of RX but the interrupt request (IRQ=1) is sent
when RX is finished.
B5
Irq_fifo
FIFO is high or low
Signals when the FIFO is high or low (more than 8 bits during RX or
less than 4 bits during TX). See Section 5.12.2 for details.
B4
Irq_err1
CRC error
Indicates receive CRC error only if B7 (no RX CRC) of ISO Control
register is set to 0.
B3
Irq_err2
Parity error
Indicates parity error for ISO14443A
B2
Irq_err3
Byte framing or EOF error
Indicates framing error
B1
Irq_col
Collision error
Collision error for ISO14443A and ISO15693 single subcarrier. Bit is
set if more then 6 or 7 (as defined in register 0x01) are detected
inside one bit period of ISO 14443A 106kbit/s.
Collision error bit can also be triggered by external noise.
B0
Irq_noresp
No-response timeinterrupt
No response within the "No-response time" defined in RX
No-response Wait Time register (0x07). Signals the MCU that next
slot command can be sent. Only for ISO 15693.
To reset (clear) the register 0x0C and the IRQ line, the register must be read. During transmit, the
decoder is disabled, and only bits B5 and B7 can be changed. During receive, only bit B6 can be
changed, but does not trigger the IRQ line immediately. The IRQ signal is set at the end of the transmit or
receive phase.
Register Description
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Collision Position and Interrupt Mask Registers (0x0D and 0x0E)
Table 6-20. Collision Position and Interrupt Mask Register (0x0D)
Default Settings: Register default is set to 0x3E at POR = H and EN = L. Collision bits reset automatically after read operation.
Bit No.
Bit Name
B7
Col9
Bit position of collision MSB
B6
Col8
Bit position of collision
B5
En_irq_fifo
Interrupt enable for FIFO
Default = 1
B4
En_irq_err1
Interrupt enable for CRC
Default = 1
B3
En_irq_err2
Interrupt enable for Parity
Default = 1
En_irq_err3
Interrupt enable for Framing
error or EOF
Default = 1
B1
En_irq_col
Interrupt enable for collision error Default = 1
B0
En_irq_noresp
B2
Function
Enables no-response interrupt
Description
Supports ISO14443A
Default = 0
Table 6-21. Collision Position Register (0x0E)
Function: Displays the bit position of collision or error
Default Settings: Register default is set to 0x00 at POR = H and EN = L. Automatically reset after read operation.
58
Bit No.
Bit Name
B7
Col7
B6
Col6
B5
Col5
B4
Col4
B3
Col3
B2
Col2
B1
Col1
B0
Col0
Function
Description
Bit position of collision MSB
ISO14443A mainly supported; in the other protocols, this register
shows the bit position of error. Either frame, SOF/EOF, parity, or
CRC error.
Bit position of collision LSB
Register Description
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6.1.3.3
RSSI Levels and Oscillator Status Register (0x0F)
Table 6-22. RSSI Levels and Oscillator Status Register (0x0F)
Function: Displays the signal strength on both reception channels and RF amplitude during RF-off state.
The RSSI values are valid from reception start till start of next transmission.
Bit No.
Bit Name
B7
Unused
Function
B6
osc_ok
Crystal oscillator stable indicator
B5
rssi_x2
MSB RSSI value of auxiliary RX
(RX_IN2)
B4
rssi_x1
Auxiliary channel RSSI
B3
rssi_x0
MSB RSSI value of auxiliary RX
(RX_IN2)
B2
rssi_2
MSB RSSI value of Main RX
(RX_IN1)
B1
rssi_1
Main channel RSSI
B0
rssi_0
LSB RSSI value of Main RX
(RX_IN1)
Description
13.56-MHz frequency stable (approximately 200 µs)
Auxiliary channel is by default RX_IN2. The input can be swapped
by B3 = 1 (Chip State Control register). If "swapped", the auxiliary
channel is connected to RX_IN1 and the auxiliary RSSI represents
the signal level at RX_IN2.
Active channel is default and can be set with option bit B3 = 0 of
Chip State Control register.
RSSI measurement block is measuring the demodulated envelope signal (except in case of direct
command for RF amplitude measurement described later in direct commands section). The measuring
system is latching the peak value, so the RSSI level can be read after the end of receive packet. The
RSSI value is reset during next transmit action of the reader, so the new tag response level can be
measured. The RSSI levels calculated to the RF_IN1 and RF_IN2 are shown in Section 5.7.1.1 and
Section 5.7.1.2. The RSSI has 7 steps (3 bits) with 4-dB increment. The input level is the peak to peak
modulation level of RF signal measured on one side envelope (positive or negative).
Register Description
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Test Registers
6.1.4.1
Test Register (0x1A)
Table 6-23. Test Register (0x1A) (for Test or Direct Use)
Default Settings: Register default is set to 0x00 at POR = H and EN = L.
Bit No.
Bit Name
B7
OOK_Subc_In
Function
Subcarrier input
MOD_Subc_Ou
Subcarrier output
t
B6
B5
MOD_Direct
B4
Description
OOK Pin becomes decoder digital input
MOD Pin becomes receiver subcarrier output
Direct TX modulation and RX reset
MOD Pin becomes receiver subcarrier output
o_sel
First stage output selection
o_sel = L: Second stage output used for analog
out and digitizing
o_sel = H: Second stage output used for analog
out and digitizing
B3
low2
Second stage gain -6 dB, HP corner freq/2
B2
low1
First stage gain -6 dB, HP corner freq/2
B1
zun
Input followers test
B0
Test_AGC
6.1.4.2
AGC test, AGC level is seen on rssi_210 bits
Test Register (0x1B)
Table 6-24. Test Register (0x1B) (for Test or Direct Use)
Default Settings: Register default is set to 0x00 at POR = H and EN = L. When a test_dec or test_io is set, IC is switched to test mode.
Test Mode persists until a stop condition arrives. At stop condition the test_dec and test_io bits are cleared.
Bit No.
Bit Name
B7
test_rf_level
Function
Description
RF level test
B6
B5
B4
60
B3
test_io1
B2
test_io0
I/O test
Not implemented
B1
test_dec
Decoder test mode
B0
clock_su
Coder clock 13.56 MHz
Register Description
For faster test of coders
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6.1.5
FIFO Control Registers
6.1.5.1
FIFO Status Register (0x1C)
Table 6-25. FIFO Status Register (0x1C)
Function: Low nibbles of complete bytes to be transferred through FIFO. Information about a broken byte and number of bits to be
transferred from it
Bit No.
Bit Name
B7
RFU
B7 = 0
Reserved for future use (RFU)
B6
Fhil
FIFO level high
Indicates that 9 bytes are already in the FIFO (for RX) (also see
register 0x0C bit 5)
B5
Flol
FIFO level low
Indicates that only 3 bytes are in the FIFO (for TX) (also see
register 0x0C bit 5)
B4
Fove
FIFO overflow error
Too many bytes were written to the FIFO
B3
Fb3
FIFO bytes fb[3]
B2
Fb2
FIFO bytes fb[2]
B1
Fb1
FIFO bytes fb[1]
B0
Fb0
FIFO bytes fb[0]
6.1.5.2
Function
Description
Bits B0:B3 indicate how many bytes that are loaded in FIFO were
not read out yet (displays N – 1 number of bytes). If 8 bytes are in
the FIFO, this number is 7 (also see register 0x0C bit 6).
TX Length Byte1 Register (0x1D) and TX Length Byte2 Register (0x1E)
Table 6-26. TX Length Byte1 Register (0x1D)
Function: High two nibbles of complete, intended bytes to be transferred through FIFO
Default Settings: Register default is set to 0x00 at POR and EN = 0. It is also automatically reset at TX EOF.
Bit No.
Bit Name
Function
B7
Txl11
Number of complete byte bn[11]
B6
Txl10
Number of complete byte bn[10]
B5
Txl9
Number of complete byte bn[9]
B4
Txl8
Number of complete byte bn[8]
B3
Txl7
Number of complete byte bn[7]
B2
Txl6
Number of complete byte bn[6]
B1
Txl5
Number of complete byte bn[5]
B0
Txl4
Number of complete byte bn[4]
Description
High nibble of complete, intended bytes to be transmitted
High nibble of complete, intended bytes to be transmitted
Table 6-27. TX Length Byte2 Register (0x1E)
Function: Low nibbles of complete bytes to be transferred through FIFO. Information about a broken byte and number of bits to be
transferred from it.
Default Settings: Register default is set to 0x00 at POR and EN = 0. It is also automatically reset at TX EOF.
Bit No.
Bit Name
Function
B7
Txl3
Number of complete byte bn[3]
B6
Txl2
Number of complete byte bn[2]
B5
Txl1
Number of complete byte bn[1]
B4
Txl0
Number of complete byte bn[0]
B3
Bb2
Broken byte number of bits bb[2]
B2
Bb1
Broken byte number of bits bb[1]
B1
Bb0
Broken byte number of bits bb[0]
B0
Bbf
Broken byte flag
Description
High nibble of complete, intended bytes to be transmitted
Number of bits in the last broken byte to be transmitted.
It is taken into account only when broken byte flag is set.
B0 = 1, indicates that last byte is not complete 8 bits wide.
Register Description
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7 System Design
7.1
Layout Considerations
Keep all decoupling capacitors as close to the IC as possible, with the high-frequency decoupling
capacitors (10 nF) closer than the low-frequency decoupling capacitors (2.2 µF).
Place ground vias as close as possible to the ground side of the capacitors and reader IC pins to minimize
any possible ground loops.
It is not recommend using any inductor sizes below 0603 as the output power can be compromised. If
smaller sized inductors are absolutely necessary, the designer must confirm output performance.
Pay close attention to the required load capacitance of the used crystal and adjust the two external shunt
capacitors accordingly. Follow the recommendations of the crystal manufacturer for those values.
There should be a common ground plane for the digital and analog sections. The multiple ground sections
or "islands" should have vias that tie the different sections of the planes together.
Ensure that the exposed thermal pad at the center of the IC is properly laid out. It should be tied to ground
to help dissipate heat from the package.
Trace line lengths should be minimized whenever possible, particularly the RF output path, crystal
connections, and control lines from the reader to the microprocessor. Proper placement of the TRF7960A,
microprocessor, crystal, and RF connection/connector help facilitate this.
Avoid crossing of digital lines under RF signal lines. Also, avoid crossing of digital lines with other digital
lines whenever possible. If the crossings are unavoidable, 90° crossings should be used to minimize
coupling of the lines.
Depending on the production test plan, the designer should consider possible implementations of test
pads and/or test vias for use during testing. The necessary pads/vias should be placed in accordance with
the proposed test plan to help enable easy access to those test points.
If the system implementation is complex (for example, if the RFID reader module is a subsystem of a
greater system with other modules such as Bluetooth, WiFi, microprocessors, and clocks), special
considerations should be taken to ensure that there is not any noise coupling into the supply lines. If
needed, special filtering/regulator considerations should be used to minimize or eliminate noise in these
unique systems.
For more information/details on layout considerations, see the TRF796x HF-RFID Reader Layout Design
Guide (SLOA139).
7.2
Impedance Matching TX_Out (Pin 5) to 50 Ω
The output impedance of the TRF7960A when operated at full power out setting is nominally 4 + j0 (4 Ω
real). This impedance must be matched to a resonant circuit and TI recommends matching circuit from
4 Ω to 50 Ω, as commercially available test equipment (for example, spectrum analyzers, power meters,
and network analyzers) are 50-Ω systems. See Figure 7-1 and Figure 7-2 for an impedance match
reference circuit. This section explains how the values were calculated.
Starting with the 4-Ω source, Figure 7-1 and Figure 7-2 shows the process of going from 4 Ω to 50 Ω by
showing it represented on a Smith Chart simulator (available from http://www.fritz.dellsperger.net/). The
elements are grouped together where appropriate.
62
System Design
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Figure 7-1. Impedance Matching Circuit
This yields the following Smith Chart Simulation:
Figure 7-2. Impedance Matching Smith Chart
Resulting power out can be measured with power meter/spectrum analyzer with power meter function or
other equipment capable of making a "hot" measurement. Take care to observe maximum power input
levels on test equipment and use attenuators whenever available to avoid any possibility of damage to
expensive equipment. Expected output power levels under various operating conditions are shown in
Table 5-3.
7.3
Reader Antenna Design Guidelines
For HF antenna design considerations using the TRF7960A, see the following documentation:
Antenna Matching for the TRF7960 RFID Reader (SLOA135)
TRF7960TB HF RFID Reader Module User's Guide, with antenna details at end of manual (SLOU297)
System Design
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PACKAGE OPTION ADDENDUM
www.ti.com
2-Jun-2011
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package
Drawing
Pins
Package Qty
Eco Plan
(2)
Lead/
Ball Finish
MSL Peak Temp
(3)
TRF7960ARHBR
ACTIVE
QFN
RHB
32
3000
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
TRF7960ARHBT
ACTIVE
QFN
RHB
32
250
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
Samples
(Requires Login)
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
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