SM1231
USER GUIDE
SM1231 RF MODULE
USER GUIDE
Revision 1.0 11/2009
© Semtech 2009
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SM1231
USER GUIDE
Table of Contents
Table of Contents.......................................................................................................................................... 2
Index of Figures ............................................................................................................................................ 2
Index of Tables.............................................................................................................................................. 2
1 Introduction ............................................................................................................................................ 3
2 Reference Design .................................................................................................................................. 3
3 PCB Layout............................................................................................................................................ 6
4 BOM ....................................................................................................................................................... 7
5 References............................................................................................................................................. 7
Index of Figures
Figure 1: SM1211 Overview (Top View) ....................................................................................................... 3
Figure 2: SM1231 Schematic Diagram ......................................................................................................... 5
Figure 3: SM1231 PCB Layout (Top View)................................................................................................... 6
Index of Tables
Table 1: MCU Connector Pin Description ..................................................................................................... 4
Table 2: SM1231 915 MHz BOM .................................................................................................................. 7
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SM1231
USER GUIDE
1 Introduction
The purpose of this tool is to provide a development platform of the SX1231. User can build his
application prototype by simply connecting the module to his target microcontroller and start developing
his application software. The SM1231 module integrates the SX1231 reference design (chip + external
components) plus miscellaneous useful connectors.
Note that this module is also used for the SX1231SKB Evaluation Kit.
It is recommended that this user guide be read in conjunction with the SX1231 datasheet.
2 Reference Design
As illustrated in Figure 1, below, the SM1231 reference design module consists of the following:
• Reference Design: This section includes the chip but also all the external components in an
optimized BOM and form factor. When the user wishes to incorporate the SX1231 to PCB, it is
strongly recommended that this reference design (i.e. schematics, placement, layout, BOM, etc...)
is copied “as is” in the final application board to guarantee optimum performance, regulatory
compliance and lowest development time and design effort.
• MCU Connector: Enables the user to connect the SX1231 control and interface pins to the host
microcontroller (please refer to the SX1231 datasheett for further information).
SMA
Connector
VDD Jumper
Reference
Design
MCU Connector
Figure 1: SM1211 Overview (Top View)
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USER GUIDE
•
•
SMA Connector: Provided for SMA Cable or antenna connection. Each board is delivered with a
quarter-wave SMA antenna appropriate to the frequency band of operation. Note that the
SM1231 module has two independent connectorized RF ports; RF_IO, the common LNA and low
power transmitter PA port and RF_PA, the high power transmitter port.
VDD jumper: Enables current consumption to be monitored and / or apply independent power
supply to the module. When VDD jumper is made, power should be supplied via the MCU
connector.
The pin-out of the MCU connector is tabulated below in Table 1.
PIN #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
NAME
SCK
VDD
MOSI
GND
DIO1/DCLK
DIO3
NSS
MISO
DIO5
RESET
DIO4
DIO0
RXTX
DIO1/DCLK
DIO2/DATA
-
TYPE
I
I
I
I/O
I/O
I
O
I/O
I/O
I/O
O
I/O
I/O
-
DESCRIPTION
SPI Clock Input
Supply Voltage Connection
SPI Data Input
Ground Connection
Digital I/O, Software Configurable
Digital I/O, Software Configurable
SPI Chip Select
SPI Data Output
Digital I/O, Software Configurable
Reset Trigger Input / POR Flag
Digital I/O, Software Configurable
Digital I/O, Software Configurable
RX/TX Switch Control; High in TX
Not Connected
Digital I/O, Software Configurable
Not Connected
Digital I/O, Software Configurable
Not Connected
Not Connected
Not Connected
Table 1: MCU Connector Pin Description
The SM1231 reference design is available for download from the Semtech website, and contains the
latest schematic, PCB Gerber files and BOMs for 315 MHz, 434 MHz, 868 MHz and 915 MHz frequency
bands of operation.
The SM1231 Schematic diagram is illustrated in Figure 2.
Software drivers are available for the SX1231 and can be found in technical note TN8000.18 and source
code ("XE8000 Driving XE1200 Transceivers Standard API Definitions") available for download from the
Semtech website.
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SM1231
USER GUIDE
Figure 2: SM1231 Schematic Diagram
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USER GUIDE
3 PCB Layout
As illustrated below in Figure 3, the SM1231 reference design PCB layout has the following
characteristics:
• Compact active area reference design () which can easily be accommodated in a very small PCB
• Standard PCB technology (2 layers, 1.6 mm / 63 mils FR4 dielectric)
Reference
Design Area
Figure 3: SM1231 PCB Layout (Top View)
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SM1231
USER GUIDE
4 BOM
An example BOM for the 915 MHz variant of the SM1231 is tabulated in Table 2.
REF
U1
R15
C1
C2
C3
C4
C5
C6
C7
C8
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
L1
L2
L3
L4
L5
L6
L7
L8
Q1
VALUE
SX1231
0R
10μF
3.3pF
N/F
6.8pF
N/F
22pF
8.2pF
10nF
100nF
100nF
100nF
15pF
15pF
100nF
68pF
4.7pF
8.2pF
N/F
6.8pF
N/F
5.6pF
5.6nH
5.6nH
22nH
2.7nH
3.9nH
33nH
6.8nH
6.8nH
32.000MHz
TOL (±)
1%
20%
0.25pF
0.5pF
5%
0.5pF
10%
10%
10%
5%
5%
5%
10%
5%
0.25pF
5%
0.5pF
0.5pF
0.2nH
0.2nH
5%
0.5nH
0.2nH
5%
5%
5%
-
SIZE
VQFN24
0402
0603
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
0402
NX2520SA
COMMENT
SX1231 Low-Power UHF Integrated Transceiver
External RESET pin
Decoupling
PA_BOOST Matching (Comp. Value is Band Specific)
PA_BOOST Matching (Comp. Value is Band Specific)
PA_BOOST Matching (Comp. Value is Band Specific)
PA_BOOST Matching (Comp. Value is Band Specific)
PA_BOOST Matching (Comp. Value is Band Specific)
PA_BOOST Matching (Comp. Value is Band Specific)
Decoupling
Decoupling
Decoupling
Decoupling
Crystal Load Capacitor
Crystal Load Capacitor
Decoupling
Decoupling
RFIO Matching (Comp. Value is Band Specific)
RFIO Matching (Comp. Value is Band Specific)
RFIO Matching (Comp. Value is Band Specific)
RFIO Matching (Comp. Value is Band Specific)
RFIO Matching (Comp. Value is Band Specific)
RFIO Matching (Comp. Value is Band Specific)
PA_BOOST Matching (Comp. Value is Band Specific)
PA_BOOST Matching (Comp. Value is Band Specific)
PA_BOOST Matching (Comp. Value is Band Specific)
PA_BOOST Matching (Comp. Value is Band Specific)
RFIO Matching (Comp. Value is Band Specific)
RFIO Matching (Comp. Value is Band Specific)
RFIO Matching (Comp. Value is Band Specific)
RFIO Matching (Comp. Value is Band Specific)
NDK Surface mount type crystal ±10ppm, CLoad=10pF
Table 2: SM1231 915 MHz BOM
5 References
•
•
SX1231 Datasheet
TN8000.18 Technical Note "XE8000 driving XE1200 transceivers Standard API definitions"
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SM1231
USER GUIDE
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