STMicroelectronicsS R3911BD1 NFC card reader board User Manual Manual

STMicroelectronics NFC card reader board Manual

Manual

Download: STMicroelectronicsS R3911BD1 NFC card reader board User Manual Manual
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Document ID3523975
Application IDk1g9aiUBrnqoJ7ukRVHG6g==
Document DescriptionManual
Short Term ConfidentialNo
Permanent ConfidentialNo
SupercedeNo
Document TypeUser Manual
Display FormatAdobe Acrobat PDF - pdf
Filesize52.46kB (655798 bits)
Date Submitted2017-08-23 00:00:00
Date Available2017-08-23 00:00:00
Creation Date2017-07-27 08:15:52
Producing SoftwareAcrobat Distiller 11.0 (Windows)
Document Lastmod2017-07-27 08:15:52
Document TitleDiscovery kit for the ST25R3911B high performance HF reader / NFC initiator
Document CreatorC2 v4.2.0220 build 670 - c2_rendition_config : Techlit_Active
Document Author: STMICROELECTRONICS

UM2042
User manual
Discovery kit for the ST25R3911B
high performance HF reader / NFC initiator
Introduction
The ST25R3911B-DISCO is a ready-to-use development kit to evaluate the functions of the
high performance HF reader / NFC initiator ST25R3911B in Reader mode for contactless
applications.
The ST25R3911B-DISCO kit supports
• ISO 18092 (NFCIP-1) active P2P
• ISO 14443A and ISO14443B
• ISO 15693
• FeliCa™
• VHBR, with 6.8 Mbit/s PCD to PICC framing and 3.4 Mbit/s PICC to PCD framing
• Up to 1.4 W output power with differential antenna
• Possibility of driving two antennas in single ended mode, with automatic antenna tuning
(AAT) system
• Inductive and capacitive Wake-up
• User selectable and automatic gain control
• Transparent and Stream modes to implement MIFARE® Classic compliant or other
custom protocols
The evaluation kit includes
• the STM32L476RET6, a 32-bit microcontroller with 512 KB of Flash memory
• a 105 mm x 52 mm, two turns antenna etched on the PCB, and its VHBR tuning circuit
• a Micro-USB connector for communication with the host PC and board powering
• six LEDs indicating the presence of the RF field and of the protocol used to communicate.
Figure 1. ST25R3911B-DISCO PCB (top view)
July 2017
DocID029132 Rev 2
1/25
www.st.com
Contents
UM2042
Contents
Quick start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1
Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2
System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2
Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3
2.2.1
USB connectivity and power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.2
STM32L4 MCU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.3
ST25R3911B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.4
Antenna and matching network components . . . . . . . . . . . . . . . . . . . . . . 8
PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.1
PCB overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3.2
PCB layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Antenna matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Federal Communications Commission (FCC)
and Industry Canada (IC) compliance statements . . . . . . . . . . . . . . . . 22
4.1
4.2
2/25
FCC Compliance Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1.1
Part 15.19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1.2
Part 15.21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1.3
Part 15.105 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.1.4
FCC ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Formal notices required by the Industry Canada (“IC”) . . . . . . . . . . . . . . 22
4.2.1
Compliance Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.2.2
Declaration de ConformitĂŠ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.2.3
IC ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
DocID029132 Rev 2
UM2042
List of tables
List of tables
Table 1.
Table 2.
NFC Forum matching alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
DocID029132 Rev 2
3/25
List of figures
UM2042
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
4/25
ST25R3911B-DISCO PCB (top view). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Functional block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Schematics overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
USB interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
STM32L476 schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
ST25R3911B schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Antenna and matching network schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
PCB overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
PCB layout, top layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
PCB layout, mid layer 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
PCB layout, mid layer 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
PCB layout, bottom layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
VHBR matching with an AAT setting of 8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
NFC Forum matching with an AAT setting of 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
DocID029132 Rev 2
UM2042
Quick start
Quick start
The ST25R3911B-DISCO is connected to a PC via USB to show the features of the
ST25R3911B chip. To do so, use the software STSW-ST25R001 to control all the functions
of the discovery kit.
1.1
Getting started
Connect the discovery kit to a PC using a micro USB cable. The USB port of the PC must be
capable of delivering at least 250 mA at 5 Volt supply.
To control the board, download the software STSW-ST25R001 from www.st.com and install
it. Further information on how to operate the software can be found in the user manual
UM2177 “PC software for the ST25R3911B-DISCO kit”, available on www.st.com.
1.2
System requirements
•
WindowsÂŽ PC (Windows 7 recommended)
•
USB port, capable of delivering at least 250 mA at 5 V supply (1.25 W)
•
Unit must be supplied by a Safety Extra Low Voltage (SELV) limited power source
through the USB port, the source should not exceed 60 Vdc / 8 A / 100 VA
•
Micro-USB cable
DocID029132 Rev 2
5/25
24
Hardware
UM2042
Hardware
The PCB (Printed Circuit Board) is connected via USB to the PC. The STSW-ST25R001 PC
software controls the STM32 MCU located on the PCB. The STM32 MCU then operates the
ST25R3911B via SPI.
The ST25R3911B is connected directly to the 5 V supply of the USB bus. An LDO converts
this voltage down to 3.3 V, to supply the microcontroller.
A green LED close to the USB plug indicates if the board is powered. Six blue LEDs indicate
the mode of operation (transmit / receive) and which technologies are in use.
The antenna runs along the PCB perimeter.
2.1
Block diagram
Figure 2 shows the functional block diagram of the board.
Figure 2. Functional block diagram
675%',6&2
/'385
9
+RVW3&
86%
(&0)
&0;
9
670/5(
63,
N+]
FU\VWDO
675%
3&%
0DWFKLQJ
QHWZRUN DQWHQQD
0+]
FU\VWDO
069
2.2
Schematics
As indicated in Figure 3, the schematics can be split into four main parts
6/25
•
USB connectivity and power supply (Figure 4)
•
STM32 MCU (Figure 5)
•
ST25R3911B (Figure 6)
•
Antenna and matching network components (Figure 7)
DocID029132 Rev 2
UM2042
2.2.1
Hardware
USB connectivity and power supply
The ST25R3911B-DISCO board can be connected via USB to a host device.
Right behind the Micro-USB plug, an ECMF02 common mode filter with ESD protection for
USB 2.0 interface is placed. The common mode filter is connected to VBUS and to the
D+/D- data lines of the USB. All the USB terminals are ESD-protected by the built-in ESD
diodes of the ECMF02.
Additionally, the power supply filter for the 5 V supplies the 3.3 V LDO, that, in turn, supplies
the microcontroller.
A green LED is connected to the USB VBUS supply and shows the USB-power status.
2.2.2
STM32L4 MCU
This schematic includes the microcontroller needed to operate the NFC reader IC.
The MCU is clocked by a 32.768 kHz crystal. The MCU uses an internal PLL to generate the
48 MHz USB clock and the 80 MHz core clock from the provided 32.768 kHz.
Connector P201 is a JTAG/SWD interface to assist in software development. It can be
connected to an external ST-LINK/V2 device using a 9-pin CortexÂŽ-M adapter.
The six blue LEDs (LED201 to LED206) show the current mode of communication. If
multiple protocols are active at the same time, then all corresponding LEDs are turned on.
The five resistors (R218 to R222) can be used to disconnect the MCU from SPI interface
header P204. This SPI cross-connect mode can be used to operate the ST25R3911B with a
different MCU PCB by cross connecting the ST25R3911B SPI to the second MCU PCB.
Connectors P202 and P203 can be used to connect an external UART or I2C host device to
the MCU.
2.2.3
ST25R3911B
The ST25R3911B is directly connected to the filtered 5 V USB supply, and there are
additional supply filtering components placed close to it. The jumper JP301 can be used to
measure the supply current of the chip. If this measurement is performed, the ferrite bead
L301 has to be removed.
Capacitors C301 to C304 provide additional filtering. All decoupling capacitors have been
placed as close as possible to the ST25R3911B. Special care has been taken for C310,
C302, C314 and C301, as they are the decoupling capacitors for the high power driver
stage.
In order to demonstrate the capacitive wake-up feature, two capacitive electrodes are
placed on the PCB. Additional electrodes can be connected using UFL connectors on P301
and P302.
For SPI cross-connecting to another reader PCB, the resistors R301 to R305 can be
removed. Then the STM32L4 MCU SPI can be connected to the ST25R3911B on any
customer PCB via header P204.
Thanks to J303 it is possible to bypass the internal VSP_RF regulator, this is required in
case output currents higher than 200 mA need to be supplied.
DocID029132 Rev 2
7/25
24
Hardware
2.2.4
UM2042
Antenna and matching network components
This schematic contains the matching network and the automatic antenna tuning capacitors,
as well as the alternative NFC Forum matching components. In the default configuration,
the ST25R3911B-DISCO is populated with a VHBR matching, with communication speeds
up to 3.4 Mbps.
To support VHBR, the antenna is matched to a system Q-Factor of 8. By switching to the
NFC Forum matching components the system Q-Factor is increased to 16. This can
increase the read range up to 20%, depending on the used communication technology, but
limits the maximum supported communication bit rate to 848 kbps. Additional details about
antenna matching can be found on www.st.com/st25r.
8/25
DocID029132 Rev 2
DocID029132 Rev 2
SPI/Power_Con
Antenna_Con
Date: 31.05.2017
Time: 10:09:36
File: Project Overview.SchDoc
A4
Size:
Number:
ST25R3911B-DISCO
Title
B1
Sheet 3 of 7
Revision:
Antenna_Con
U_Antenna
Antenna.SchDoc
MDG NFC & Reader Competence Center
SPI/Power_Con
U_ST25R3911B
ST25R3911B.SchDoc
PM/USB_con
U_Microcontroller
Microcontroller.SchDoc
PM/USB_con
U_Power Management
Power Management.SchDoc
Figure 3. Schematics overview
UM2042
Hardware
9/25
D
GND
C_1Îź_0603_X5R
C104
V_RF
3V3 LDO
ÎźUSB
GND
ID
D+
D-
P101
PWR
Shield
EN
VI
D+
D-
NC
VO
GND
ID GND
ECMF02-4CMX8
D+
D-
U101
VBUS GND
LD39050PU33R
PG
U102
USB Interface
GND
DocID029132 Rev 2
GND
10/25
C105
J101
closed 0R
L102
FB_0603_0R
C_2Îź2_0402_X5R
C106
3V3
GND
C_10n_0402_X7R
USBD_P
USBD_N
L103
FB_0603_0R
GND
C102
C103
B1
Sheet 4 of 7
Revision:
USBD_P
USBD_N
V_RF
3_3V
PM/USB_con
Date: 31.05.2017
Time: 10:09:36
File: Power Management.SchDoc
Number:
A4
Size:
USBD_P
USBD_N
V_RF
ST25R3911B-DISCO
3V3
LED101
R101
Title
GND
C_1Îź_0603_X5R
C_10Îź_0603_X5R
FB_0603
C_10Îź_0603_X5R
C101
L101
V_RF
Figure 4. USB interface
G104
ST Microelectronics
Logo_STM
G103
ST25
Logo_ST25
G102
RoHS
Logo_RoHS
G101
ESD
Logo_ESD
MDG NFC & Reader Competence Center
PM/USB_con
Hardware
UM2042
D
C210
C211
Pin 47+48
PC8
PC9
PC10
PC11
PC12
PC13
PC14 - OSC32_IN
PC15 - OSC32_OUT
32
64
48
19
AVDD 13
C213
39
40
51
52
53
PD2
VSSA
NRST
BOOT0
C214
Pin 1
STM32L476RE
C215
C216
Pin 12+13
AVDD
AVDD
SCL
SDA
31
63
47
18
54
12
60
LED4
LED5
/SS_MCU
T_SWO
LED3
AVDD
VDD
VSS/VCAP1
VDD
VSS
VDD/VUSB/VSA/PF7VSS/VCAP2/PF6
VDD/PF5
VSS/PF4/PA3
VDDA/VREF+
VBAT/VLCD
PF0/PD0/PH0 - OSC_IN
PF1/PD1/PH1 - OSC_OUT
U201B
Pin 63+64 Pin 31+32
C212
FB_0603
L201
PC0
PC1
PC2
PC3
PC4
PC5
PC6
PC7
STM32L476RE
Y201
d.n.p.
10
11
24
25
37
38
26
27
28
55
56
57
58
59
61
62
29
30
33
34
35
36
C_1Îź_0402_X5R
X5R
C_4Îź7_0402_X5R C_4Îź7_0402_X5R
C_100n_0402_X7R
C_100n_0402_X7R
C_100n_0402_X7R
C_100n_0402_X7R
C_100n_0402_X7R
C209
Pin 18+19
3V3
3V3 d.n.p.
C206
d.n.p.
C205
LP_UART_RX
LP_UART_TX
T_JTMS
T_JTCK
T_JTDI
LED2
SCLK_MCU
MISO_MCU
MOSI_MCU
LED6
UART_TX
UART_RX
MCU_D_N
MCU_D_P
IRQ_MCU
LED1
497-15872-ND
U201A
14
PA0
PB0
15
PA1
PB1/VREF+
16
PA2
PB2
17
PA3/SAR_VREF+
PB3
20
PA4
PB4
21
PA5
PB5
22
PA6
PB6
23
PA7
PB7
41
PA8
PB8
42
PA9
PB9
43
PA10
PB10/PE8
44
PA11
PB11/VCAP1
45
PA12
PB12/SD_VREF+
46
PA13
PB13/PB14
49
PA14
PB14/PB15
50
PA15
PB15/PD8
Microcontroller
T_NRST
C_4p3_0402
C_4p3_0402
X201
32.768 kHz
C204
C203
T_JTDI
T_NRST
R210
R211
S201
R223
S202
C_100n_0402_X7R
C207
C_100n_0402_X7R
C208
3V3
R213
C202
R205
LED2
LED3
R220
Date: 31.05.2017
Time: 10:09:36
File: Microcontroller.SchDoc
Number:
A4
Size:
P204 d.n.p.
ST25R3911B-DISCO
R222
Title
/SS_MCU
MISO_MCU R221
IRQ_MCU
SEN
GND
3V3 V_RF
MISO
INTR
MOSI
3V3
SCLK
SCL
SDA
LP_UART_TX
LP_UART_RX 3V3
SCLK_MCU R218
R217
R216
R215
R214
MOSI_MCU R219
d.n.p.
d.n.p.
P203
R203
LED1
B1
Sheet 5 of 7
Revision:
V_RF
3V3
open
open
J202
J201
LP_UART_TX
LP_UART_RX
SPI/Power_Con
PM/USB_con
MDG NFC & Reader Competence Center
UART_TX
UART_RX
MCU_CLK
INTR
MISO
MOSI
SCLK
SEN
V_RF
3_3V
SPI/Power_Con
USBD_N
USBD_P
V_RF
3_3V
PM/USB_con
INTR
MISO
MOSI
SCLK
SEN
V_RF
USBD_N
USBD_P
3V3
LED4
LED5
LED6
LED201
R206
LED202
R208
LED203
R209
LED204
LED205
LED206
R202
Interface
P202
MCU_D_N
MCU_D_P
T_SWO
R207
R212
T_JTCK
T_JTMS
R204
R201
3V3
C_56p_0402
C_56p_0402
C201
USBD_N
USBD_P
Header 10
10
P201
SWD
Case
Case
DocID029132 Rev 2
Figure 5. STM32L476 schematics
UM2042
Hardware
11/25
D
P301
P302
GND
d.n.p.
GND
GND
GND
d.n.p.
GND
GND
GND
R306
C306
GND
R307
C_12p_0402
C_12p_0402
C305
CSI_out
CSO_out
SEN_11
MISO_11
MOSI_11
SCLK_11
INTR_11
d.n.p.
CSO
CSI
JP301
FB_0603
L301
C308
GND
C_8p2_0402
Y301
V_RF
XTI
XTO
CSO
CSI
NFC Initiator / HF Reader IC
C310
C311
C312
RFI1
RFI2
RFO1
RFO2
TRIM2_3
TRIM2_0
TRIM1_0
TRIM1_1
TRIM1_2
TRIM1_3
C_100n_0402_X7R
C302
GND
GND
GND
GND
C_2Îź2_0402_X5R C_2Îź2_0402_X5R C_1Îź_0402_X5R
C_2Îź2_0402_X5R
Date: 31.05.2017
Time: 10:09:36
File: ST25R3911B.SchDoc
A4
Size:
Number:
R305
R303
R301
MCU_CLK
INTR
MISO
MOSI
SCLK
SEN
V_RF
3_3V
SPI/Power_Con
RFO1
RFO2
RFI1
RFI2
Antenna_Con
B1
Sheet 6 of 7
Revision:
Antenna_Con
SPI/Power_Con
MDG NFC & Reader Competence Center
TRIM1_0
TRIM1_0
TRIM1_1
TRIM1_1
TRIM1_2
TRIM1_2
TRIM1_3
TRIM1_3
TRIM2_0
TRIM2_0
TRIM2_1
TRIM2_1
TRIM2_2
TRIM2_2
TRIM2_3
TRIM2_3
RFO1
RFO2
RFI1
RFI2
Antenna Connection
INTR_11
MISO_11R302
MOSI_11
SCLK_11R304
SEN_11
3V3
V_RF
Controller Interface
ST25R3911B-DISCO
Title
VSP_RF
RFI1
RFI2
22
23
J303
V_RF_3911
open
RFO1
RFO2
TRIM2_0
TRIM2_1
TRIM2_2
TRIM2_3
20
18
16
14
10
11
TRIM1_0
TRIM1_1
TRIM1_2
TRIM1_3
U301
19 ST25R3911B
17
15
13
GND
d.n.p.
J302
C_10n_0402_X7R C_10n_0402_X7R C_10n_0402_X7R
C_10n_0402_X7R
C313
C314
C315
C316
C309
GND
C_1Îź_0402_X5R
C301
J301
ST25R3911 TRIM2_1
TRIM2_2
/SS
MISO
MOSI
SCLK
IRQ
MCU_CLK
GND
V_RF_3911
C303
C304
d.n.p.
C_100n_0402_X7R
C307
C_8p2_0402
25
32
29
30
31
27
28
3V3
12
GND
GND
DocID029132 Rev 2
VSP_RF
VSN_RF
VSP_D
ST25R3911 NFC Initiator / HF Reader
VSP_A
VDD_IO
VDD
VSP_D
VSN_D
AGD
VSP_A
VSN_A
26
VSP_RF
AGD
VSS
EP VSUB
24
21
33
12/25
Figure 6. ST25R3911B schematics
Hardware
UM2042
DocID029132 Rev 2
Antenna_Con
TRIM1_0
TRIM1_1
TRIM1_2
TRIM1_3
TRIM2_0
TRIM2_1
TRIM2_2
TRIM2_3
RFO1
RFO2
RFI1
RFI2
Antenna_Con
TRIM1_0
TRIM1_1
TRIM1_2
TRIM1_3
TRIM2_0
TRIM2_1
TRIM2_2
TRIM2_3
RFO1
RFO2
RFI1
RFI2
RFI2
TRIM2
RFO2
RFO1
TRIM1
RFI1
J403
TRIM2_3
TRIM2_2
TRIM2_1
TRIM2_0
TRIM1_1
TRIM1_0
C421
C_56p_0402
TRIM1_3
C407
C404
d.n.p.
d.n.p.
C422
C_56p_0402
GND
GND
closed 0R
J404
closed 0R
J405
J402
closed 0R
J401
C403_NFCF
B1
Sheet 7 of 7
GND
R402_NFCF
R401_NFCF
Revision:
C_120p_0603
C410_NFCF
C_120p_0603
Date: 31.05.2017
Time: 10:09:36
File: Antenna.SchDoc
A4
Size:
Number:
ST25R3911B-DISCO
GND
Title
MDG NFC & Reader Competence Center
Antenna Loop
NFC Forum matching
C412
C_82p_0603
C411
C_10p_0603
R402
R401
C402
C_10p_0603
C408
C_120p_0603
GND
C401
C_82p_0603
C406
C_120p_0603
J407
TRIM1
C420
C_27p_0402 closed 0R
C418
C_12p_0402
C416
C_5p6_0402
C_180p_0603
J406
TRIM2
C419
C_27p_0402 closed 0R
TRIM1_2
C417
C_12p_0402
C415
C_5p6_0402
C_180p_0603
C409
C_680p_0603 C410
GND
C405
C_680p_0603
Trim Capacitor Banks
270n
L402
270n
L401
C403
Antenna Circuit incl. EMI Filter and Matching
Antenna Connection
Figure 7. Antenna and matching network schematics
UM2042
Hardware
13/25
Hardware
UM2042
2.3
PCB layout
2.3.1
PCB overview
The PCB (see Figure 8) is organized in two halves
•
Left side: the SPI header P204 and the digital / MCU sections
•
Right side: the analog parts and the ST25R3911B.
The whole PCB is surrounded by a two turns NFC antenna.
Figure 8. PCB overview
8$57
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069
The boot button can be found right above the I2C header. If this button is pressed during the
powering or the resetting of the board, the STM32L4 will enter the boot loader mode. The
reset button is positioned between the JTAG/SWD header and the I2C header.
2.3.2
PCB layers
The PCB layout is designed considering that the ST25R3911B is a high power RF
transmitter, hence the decoupling capacitors are located as close as possible to the positive
and negative power supply pins, for example VSP_RF and VSN_RF.
Since the chip is using a differential output driver stage, the antenna matching network is
treated as a differential network. The space between the components is kept as small as
possible and the whole network is routed in a completely symmetrical way.
Via stitching and via shielding is used to maintain a low impedance and prevent short return
current loops. The RF traces are protected by via stitching in combination with guard rings
to create a via wall. This keeps the PCB electromagnetically “quiet”.
A via shield is used to create a vertical copper barrier through the PCB. This helps to reduce
crosstalk and electromagnetic interference in any route carrying an RF signal. The RFI
traces and AAT lanes are routed as close as possible to each other.
14/25
DocID029132 Rev 2
UM2042
Hardware
Top layer
The top layer (Figure 9) contains most of the components and PCB traces. The unused
areas around the ICs are filled with GND planes, guarded using via stitching. Furthermore,
important analog traces are surrounded by GND vias.
Mid layer 1
This layer (Figure 10) is a pure GND plane, providing a low ohmic DC path for the GND
connection.
Mid layer 2
Mid layer 2 (Figure 11) is used for the power distribution. It contains the power planes for the
5 V supply of the ST25R3911B and the 3.3 V supply of the microcontroller.
Bottom layer
The bottom layer (Figure 12) is mainly a GND plane, but some traces are routed through it.
DocID029132 Rev 2
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24
UM2042
Figure 9. PCB layout, top layer
Hardware
16/25
DocID029132 Rev 2
Hardware
Figure 10. PCB layout, mid layer 1
UM2042
DocID029132 Rev 2
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UM2042
Figure 11. PCB layout, mid layer 2
Hardware
18/25
DocID029132 Rev 2
Hardware
Figure 12. PCB layout, bottom layer
UM2042
DocID029132 Rev 2
19/25
Antenna matching
UM2042
Antenna matching
The default matching network assembled enables VHBR operation up to 3.4 Mbps.
Components for an optional NFC Forum matching are placed on the board. Exchanging the
components as indicated in Table 1 will increase the Q factor of the antenna system. VHBR
communication at 3.4 Mbps and 1.7 Mbps bit rate will not be supported anymore, but the
read range for lower data rate applications will increase, up to 20%.
The matching impedance will remain the same when switching between the two matchings.
VHBR matching
The VHBR matching is designed with a target Q-Factor of 8. The matching impedance is
around 12.8 + j5 Ÿ. The HW based AAT algorithm will typically adjust to an AAT value of 8
(see Figure 13).
Figure 13. VHBR matching with an AAT setting of 8
NFC Forum matching
The NFC Forum matching is designed with a target Q-Factor of 16.
To switch to the NFC Forum matching the user needs to change the components listed in
Table 1.
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DocID029132 Rev 2
UM2042
Antenna matching
Table 1. NFC Forum matching alternatives
Default assembly
Value
NFC Forum replacement
Value
C403
80 pF
C403_NFCF
120 pF
C410
180 pF
C410_NFCF
120 pF
R401
3R9
R401_NFCF
1R96
R402
3R9
R402_NFCF
1R96
With the new assembled values, the matching impedance looks as in Figure 14, with a
value close to 11 + j6 Ÿ.
Figure 14. NFC Forum matching with an AAT setting of 11
The HW based AAT algorithm will typically adjust to an AAT value of 11. Due to the higher
Q-Factor the voltage on the antenna is also increasing. To have the receiver in an optimum
signal level range, the capacitors C401 and C412 can be increased to 100 pF.
DocID029132 Rev 2
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24
Federal Communications Commission (FCC) and Industry Canada (IC) compliance statements
Federal Communications Commission (FCC)
and Industry Canada (IC) compliance statements
4.1
FCC Compliance Statement
4.1.1
Part 15.19
This device complies with Part 15 of the FCC Rules. Operation is subject to the following
two conditions: (1) this device may not cause harmful interference, and (2) this device must
accept any interference received, including interference that may cause undesired
operation.
4.1.2
Part 15.21
Any changes or modifications to this equipment not expressly approved by
STMicroelectronics may cause harmful interference and void the user’s authority to operate
this equipment.
4.1.3
Part 15.105
This equipment has been tested and found to comply with the limits for a Class B digital
device, pursuant to part 15 of the FCC Rules. These limits are designed to provide
reasonable protection against harmful interference in a residential installation. This
equipment generates, uses and can radiate radio frequency energy and, if not installed and
used in accordance with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference will not occur in a
particular installation. If this equipment does cause harmful interference to radio or
television reception, which can be determined by turning the equipment off and on, the user
is encouraged to try to correct the interference by one or more of the following measures:
4.1.4
•
Reorient or relocate the receiving antenna.
•
Increase the separation between the equipment and receiver.
•
Connect the equipment into an outlet on a circuit different from that to which the
receiver is connected.
•
Consult the dealer or an experienced radio/ TV technician for help.
FCC ID
FCC ID: YCPR3911BD1
4.2
Formal notices required by the Industry Canada (“IC”)
4.2.1
Compliance Statement
This device complies with Industry Canada license-exempt RSS standard(s). Operation is
subject to the following two conditions: (1) this device may not cause interference, and (2)
this device must accept any interference, including interference that may cause undesired
operation.
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DocID029132 Rev 2
UM2042Federal Communications Commission (FCC) and Industry Canada (IC) compliance state-
4.2.2
Declaration de ConformitĂŠ
Le présent appareil est conforme aux CNR d’Industrie Canada applicables aux appareils
radio exempts de licence. L’exploitation est autorisée aux deux conditions suivantes: (1)
l’appareil ne doit pas produire de brouillage, et (2) l’utilisateur de l’appareil doit accepter tout
brouillage radioélectrique subi, même si le brouillage est susceptible d’en compromettre le
fonctionnement.
4.2.3
IC ID
IC ID: 8976B-R3911BD1
DocID029132 Rev 2
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24
Revision history
UM2042
Revision history
Table 2. Document revision history
Date
Revision
23-Jun-2017
Initial release.
Added Section 4.1.3: Part 15.105.
Updated Section 4.1.4: FCC ID and Section 4.2.3: IC ID.
Updated Figure 8: PCB overview, Figure 9: PCB layout, top layer and
Figure 12: PCB layout, bottom layer.
25-Jul-2017
24/25
Changes
DocID029132 Rev 2
UM2042
IMPORTANT NOTICE – PLEASE READ CAREFULLY
STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, enhancements, modifications, and
improvements to ST products and/or to this document at any time without notice. Purchasers should obtain the latest relevant information on
ST products before placing orders. ST products are sold pursuant to ST’s terms and conditions of sale in place at the time of order
acknowledgement.
Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or
the design of Purchasers’ products.
No license, express or implied, to any intellectual property right is granted by ST herein.
Resale of ST products with provisions different from the information set forth herein shall void any warranty granted by ST for such product.
ST and the ST logo are trademarks of ST. All other product or service names are the property of their respective owners.
Information in this document supersedes and replaces information previously supplied in any prior versions of this document.
© 2017 STMicroelectronics – All rights reserved
DocID029132 Rev 2
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Author                          : STMICROELECTRONICS
Create Date                     : 2017:07:27 08:15:52-04:00
Keywords                        : Technical Literature, 029132, Product Development, Specification, User manual, ST25R3911B-DISCO
Modify Date                     : 2017:07:27 08:15:52-04:00
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Description                     : -
Title                           : Discovery kit for the ST25R3911B high performance HF reader / NFC initiator
Document ID                     : uuid:1f7af331-919b-4da2-a206-5302ff8ef0d1
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EXIF Metadata provided by EXIF.tools
FCC ID Filing: YCPR3911BD1

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