The SPBT2532C2.AT2 is an easy to use Bluetooth module, compliant with Bluetooth v2.1 +
EDR.
The module is the smallest form factor available which provides a complete RF platform.
The SPBT2532C2.AT2 enables electronic devices with wireless connectivity, not requiring
any RF experience or expertise for integration into the final product. The SPBT2532C2.AT2
module, being a certified solution, optimizes the time to market of the final application.
The module is designed for maximum performance in the minimum possible size including
fast speed UART and 4 general purpose I/O lines, several serial interface options, and up to
1.5 Mbps data throughput.
The SPBT2532C2.AT2 is a surface mount PCB module that provides fully embedded,
ready-to-use Bluetooth wireless technology. The reprogrammable Flash memory contains
embedded firmware for serial cable replacement using the Bluetooth SPP profile.
Embedded Bluetooth AT2 command firmware is a friendly interface, which realizes a simple
control for cable replacement, enabling communication with most Bluetooth enabled
devices, provided that the devices support the SPP profile. The SPBT2532C2.AT2,
supporting iAP profile, provides communication with Android
iOS Bluetooth enabled devices.
™
, smartphones, and Apple®
An Apple authentication IC is required to exchange data with an Apple device or access an
Apple device application. The AT2 FW includes the Bluetooth SPP profile capable of
recognizing the Apple authentication chip.
Customers using the Apple authentication IC must register as developers to become an
Apple certified MFI member. License fees may apply, for additional information visit:
http://developer.apple.com/programs/which-program/index.html.
Certified MFI developers developing electronic accessories that connect to the iPod
iPhone
®
, and iPad® gain access to technical documentation, hardware components,
®
,
technical support and certification logos.
Customized firmware for peripheral device interaction, power optimization, security, and
other proprietary features may be supported and can be ordered pre-loaded and configured.
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SPBT2532C2.AT2RoHS compliance
2 RoHS compliance
ST modules are RoHS compliant and comply with ECOPACK® norms.
3 Applications
■ Serial cable replacement
■ M2M industrial control
■ Service diagnostic
■ Data acquisition equipment
■ Machine control
■ Sensor monitoring
■ Security system
■ Mobile health.
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Software architectureSPBT2532C2.AT2
4 Software architecture
4.1 Lower layer stack
●Bluetooth v2.1 + EDR
●Device power modes: active, sleep and deep sleep
●Wake-on Bluetooth feature optimized power consumption of host CPU
●Authentication and encryption
●Encryption key length from 8 bits to 128 bits
●Persistent Flash memory for BD address and user parameter storage
1. ADC pin functions are not 5 V tolerant when used as ALT pin function. Otherwise the I/O pins are all 5 V tolerant.
2. Please note that the usage of ALT function is dependant upon the firmware that is loaded into the module, and is beyond
the scope of this document. The AT command interface uses the main UART by default.
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Hardware specificationsSPBT2532C2.AT2
5.8 Pin placement
Figure 2.Pin placement
Figure 3.Ground plane diagram
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SPBT2532C2.AT2Hardware specifications
5.9 Layout drawing
Figure 4.Layout drawing
1 GPI0 01
2 GPI0 02
3 GPI0 03
4 GPI0 04
5 GND
6 ANT
7 GND
All dimensionsare in millimeters.
Drawing is not in scale.
TXD 14
RXD 13
RTS 12
CTS 11
RESET 10
BOOT 9
VIN 8
pad size: 0.76x1.07
10.5x13.5x2.5 mm (height tolerance +/- 0.1 mm)
AM14832v1
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Hardware block diagramSPBT2532C2.AT2
6 Hardware block diagram
Figure 5.SPBT2532C2.AT2 module block diagram
Battery or Supply
ARM Cortex MCU
STM32
Regulator
256K Flash
BP
Filter
Host Controller
Interface
UART
GPIO
STLC2500DB
I2S/
PCM
LPO
Clock
48K RAM
UART
AM14807v1
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SPBT2532C2.AT2Hardware design
7 Hardware design
The SPBT2532C2.AT2 module with AT2 command embedded FW supports UAR and GPIO
hardware interfaces. Note that the usage of these interfaces is dependent upon the firmware
that is loaded into the module, and is beyond the scope of this document. The AT2
command interface uses the main UART by default.
Note:1All unused pins should be left floating; do not ground.
2All GND pins must be well grounded.
3The area around the module should be free of any ground planes, power planes, trace
routings, or metal, for 6 mm from the antenna in all directions.
4Traces should not be routed underneath the module.
7.1 Module reflow installation
The SPB2532C2.AT2 is a surface mount Bluetooth module supplied on a 14-pin, 6-layer
PCB. The final assembly recommended reflow profiles are indicated here below.
The soldering phase must be executed with care: in order to avoid undesired melting
phenomenon, particular attention must be paid to the setup of the peak temperature.
The following are some suggestions for the temperature profile based on IPC/JEDEC JSTD-020C, July 2004 recommendations.
Table 8.Soldering
Profile featurePB-free assembly
Average ramp-up rate (T
Preheat:
– Temperature min. (T
– Temperature max. (T
–Time (t
Time maintained above:
– Temperature T
– Temperature T
Peak temperature (T
Time within 5 °C of actual peak temperature (T
Ramp-down rate6 °C/sec
Time from 25 °C to peak temperature8 minutes max.
min. to ts max.)(ts)
s
L
L
)240 + 0 °C
P
to TP)3 °C/sec max.
SMAX
min.)
S
max.)
S
)10-20 sec
P
150 °C
200 °C
60-100 sec
217 °C
60-70 sec
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Hardware designSPBT2532C2.AT2
Figure 6.Soldering profile
!-V
7.2 GPIO interface
All GPIOs are capable of sinking and sourcing 4 mA of I/O current. GPIO [1] is internally
pulled down with 100 kΩ (nominal) resistors.
7.3 UART interface
The UART is compatible with the 16550 industry standard. Four signals are provided with
the UART interface. The TXD and RXD pins are used for data while the CTS and RTS pins
are used for flow control.
Figure 7.Connection to host device
(OST
"LUETOOTH
-ODULE
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!-V
Page 19
SPBT2532C2.AT2Hardware design
Figure 8.Typical RS232 circuit
!-V
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Application informationSPBT2532C2.AT2
8 Application information
Here below there are some suggestions to better implement the module in the final
application.
●Avoid that traces with switching signals are routed on the motherboard below the
module. The best condition would be to have a ground plane underneath the module
●Connect the supply voltage ground of the module with the other grounds present on the
motherboard in a star ground configuration.
Keep the RF ground separate from the module supply voltage ground; the two grounds are
already connected inside the module in one point, a possible implementation can be seen in
Figure 9.
Figure 9.Example of antenna integration on the STEVAL-SPBT2ATV3
8.1 Antenna choice
The RF output pin must be connected to an antenna which may be:
●Antenna directly printed on the PCB (Figure 10)
●Integrated SMD antenna, including but not limited to the following examples
(Figure 11):
–Johanson Technology 2450T18A100S
–Antenova 30-30-A5839-01
–Murata ANCV12G44SAA127
–Pulse W3008
–Yageo CAN4311153002451K.
The external antenna connected by means of an SMA connector (Figure 12).
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SPBT2532C2.AT2Application information
Figure 10. Antenna printed on PCB
Note:This is an antenna design indication. Since antenna dimension depends on PCB material,
thickness,
please refer to antenna calculator literature.
Figure 11. SMD antenna
εr constant and design, among other parameters, to dimension it correctly,
Figure 12. SMA connector for external antenna
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Application informationSPBT2532C2.AT2
8.2 Antenna coupling
Despite the type of antenna chosen, the connection between the RF out pin and the
antenna must be realized to get the maximum power transfer.
As a general rule, the characteristic impedance (Z0) of the connection must be fixed at the
value of 50 Ω. The connection trace must be matched to respect such a condition.
50 Ω¸ matching depends on various factors and elements that must be taken into
consideration:
●Type of material, i.e. FR4 or others
●The electrical characteristics of the material, among them the electric constant, ε r, at
2.4 GHz
●PCB and traces mechanical dimensions:
– PCB thickness
– Reference ground thickness
– Trace width
– Trace thickness.
8.3 Example of trace calculation
Example of strip line calculation:
●To get a strip line of 50 Ω, using a 1 mm thick FR4 board, with an εr = 4.3 at 2.4 GHz,
with Cu thickness of 41 µm, the strip line width must be 1.9 mm (micro strip type
calculation).
Tools for calculating the characteristic impedance, based on the physical and mechanical
characteristics of the PCB, can be easily found online.
Figure 13. Parameters for trace matching
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SPBT2532C2.AT2Application information
8.4 Reset circuit
Two types of system reset circuits are detailed below.
8.4.1 External reset circuit
Figure 14. External reset circuit
2%3%4
Note:RPU ranges from 30 kΩ
to 50 kΩ internally.
8.4.2 Internal reset circuit
Figure 15. Internal reset circuit
Note:1R
2R
ranges from 30 kΩ to 50 kΩ internally.
PU
should be from 1 kΩ to 10 kΩ.
RST
!-V
2%3%4
!-V
Doc ID 023461 Rev 123/27
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Regulatory complianceSPBT2532C2.AT2
9 Regulatory compliance
●BQB
–BQB qualified design, QD ID: B016360
–Product type: End Product
–TGP version: Core 2.1/2.1 + EDR TCRL-2009-1
–Core spec version: 2.1/2.1 + EDR
–Product descriptions: Bluetooth module
●CE
–CE Expert opinion: 307-ARAJ00079
–Measurements have been performed in accordance with (report available on
request):
–EN 300 328 V 1.7.1 (2006-10)
–EN 301 489-17 V 2.1.1 (2009)
–EN60950-1:2006 +A11:2009+A1:2010
CE certified:
(a)
(b)
(c)
a. EN 300 328 V 1.7.1 (2006-10): “electromagnetic compatibility and radio spectrum matters (ERM); wideband
transmission systems; data transmission equipment operating in the 2.4 GHZ ISM band and using wideband
modulation techniques; harmonized EN covering essential requirements under article 3.2 of the R&TTE
directive”.
b. EN 301 489-17 V 2.1.1 (2009): “electromagnetic compatibility and radio spectrum matters (ERM);
electromagnetic compatibility (EMC) standard for radio equipment and services; part 17: specific condition for
2.4 GHz wideband transmission systems and 5 GHz high performance RLAN equipment”.
c. EN60950-1:2006 +A11:2009+A1:2010: “Information technology equipment - safety”.
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SPBT2532C2.AT2Ordering information
10 Ordering information
Table 9.Ordering information
Order codeDescription
SPBT2532C2.AT2Class 2 OEM Bluetooth antenna module
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Revision historySPBT2532C2.AT2
11 Revision history
Table 10.Document revision history
DateRevisionChanges
18-Jul-20121First release.
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SPBT2532C2.AT2
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