Anaren A2541R24x User manual

3
Anaren Integrated Radio
A2541R24x User’s Manual
Release Date: 11/22/13

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USER’S MANUAL
Models A2541R24A and A2541R24C
Contents
1. Overview ..........................................................................................................................................................5
1.1. A2541R24A.................................................................................................................................................5
1.2. A2541R24C.................................................................................................................................................6
1.3. Features.......................................................................................................................................................6
1.4. Theory of Operation..................................................................................................................................7
1.5. Applications.............................................................................................................................................10
2. Approvals and Usage ...................................................................................................................................11
2.1. Product Approvals..................................................................................................................................11
2.1.1. USA (Federal Communications Commission, FCC).........................................................................11
2.1.1.1. FCC Labeling Requirements ................................................................................................11
2.1.1.2. End User Manual ...................................................................................................................12
2.1.1.3. RF Exposure............................................................................................................................12
2.1.2. Canada (Industry Canada, IC)..........................................................................................................12
2.1.2.1. IC Labeling Requirements ....................................................................................................14
2.1.2.2. RF Exposure............................................................................................................................16
2.1.3. Europe (Conformité Européenne, )...............................................................................................16
2.1.4. Bluetooth Special Interest Group (SIG) ............................................................................................17
2.2. Potential Interference Sources ...............................................................................................................17
2.2.1. WLAN...............................................................................................................................................17
2.2.2. Classic Bluetooth ...............................................................................................................................18
2.2.3. Microwave ovens...............................................................................................................................18
2.2.4. Other Interference .............................................................................................................................18
2.2.5. Time critical data...............................................................................................................................19
2.3. Approved Usage .....................................................................................................................................20
2.3.1. USA and Canada...............................................................................................................................20
2.3.2. Europe ...............................................................................................................................................21
2.3.3. Bluetooth ...........................................................................................................................................21
3. Electrical Characteristics ..............................................................................................................................22
3.1. Absolute Maximum Ratings ..................................................................................................................22
3.2. Operating Conditions .............................................................................................................................23
3.3. Pin Out......................................................................................................................................................23
3.3.1. A2541R24x10 (Module with TI BLE Stack).....................................................................................23
3.3.2. A2541R24x20 (Module with Emmoco EM-Ware Firmware)...........................................................25
3.4. Recommended Layout (dimensions in mm) .......................................................................................27
3.5. Power Supply Considerations ...............................................................................................................29
4. Mechanical and Process................................................................................................................................30
4.1. Radio Module Details (dimensions in mm).........................................................................................30
4.1.1. A2541R24A ......................................................................................................................................30
4.1.2. A2541R24C.......................................................................................................................................30
4.2. Packaging Details (dimensions in mm)...............................................................................................31
4.2.1. Matrix Tray Packaging .....................................................................................................................31
4.2.2. Tape-Reel Packaging .........................................................................................................................31
4.3. Soldering...................................................................................................................................................32

4.3.1. Manual Mounting Procedure ...........................................................................................................32
4.3.2. Automated Mounting Procedure ......................................................................................................33

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1. Overview
The A2541R24A and A2541R24C are surface mount 2.4GHz RF transceivers incorporating
Bluetooth®SMART technology per the Bluetooth v4.0 core specification. The A2541R24A has
an integral antenna, whereas the A2541R24C utilizes an external antenna through a U.FL
connector (see Table 1). These modules incorporate crystals, a step down converter, the
required RF matching and filtering for regulatory compliance as well as filtering for noise
reduction and sensitivity. They operate in the global unlicensed 2.4GHz ISM/SRD frequency
band. The modules are ideal for achieving low power, long range wireless connectivity without
having to deal with extensive protocol, RF, antenna design and regulatory compliance, and
provide quick time to market. They are 100% tested to provide consistent performance.
The A2541R24A and A2541R24C modules have received regulatory approvals for modular
devices in the United States (FCC), Canada (IC) and Europe (ETSI). The modular approval
allows the end user to place either an A2541R24A or an A2541R24C with an approved antenna
inside a finished product without having to perform costly regulatory testing for an intentional RF
radiator. Section 2.3 has information on the requirements for the end user/integrator to fulfill in
order to use the modules without intentional radiator regulatory testing.
The A2541R24A and A2541R24C are based on the CC2541 SoC transceiver from Texas
Instruments (TI). The CC2541 combines the excellent performance of a leading RF transceiver
with an industry-standard enhanced 8051 microcontroller unit (MCU), 256-KB in-system
programmable flash memory, 8-KB RAM with retention in all power modes, and many other
powerful features. The CC2541 has various operating modes, making it highly suited for
systems where ultralow power consumption is required. Short transition times between
operating modes further ensure low energy consumption. All control lines are provided at
module level for full control of the operation. Please see the user’s guide for CC2541
(www.ti.com) for how to operate, program and control these modules.
The A2541R24A and A2541R24C modules are available loaded with either “BLE Stack”
firmware from Texas Instruments (part number suffix “10”) or “EM-Ware based on BLE Stack”
firmware (part number suffix “20”) from Emmoco, a leader in embedded mobile
connectivity. More information is available for the TI BLE Stack at http://www.ti.com/tool/ble-
stack, and for Emmoco EM-Ware at http://www.emmoco.com.
The A2541R24A and A2541R24C modules measure 11 mm x 19 mm x 2.5 mm. The modules
are footprint compatible with each other.
1.1. A2541R24A
The A2541R24A has an integral antenna, providing high efficiency and near omni-directional
radiation pattern. This approach offers the lowest system cost when the application allows
collocation of radio and antenna. See Figure 9 - Figure 10 for more information on antenna
location and enclosure considerations.

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1.2. A2541R24C
The A2541R24C has a compact antenna connector that allows for locating the antenna away
from the module due to form/function or in order to exit a metal enclosure. Please see Table 1
for a list of approved antennas.
1.3. Features
Features:
2.4 GHz incorporating Bluetooth Smart
technology and Proprietary RF System-
on-Chip
2.0 to 3.6 V operation
High-Performance and low-power 8051
microcontroller core
256 kB Programmable Flash
8 kB RAM with retention in all power
modes
Programmable output power up to +1
dBm
18 General Purpose I/O Pins
Features TI’s TPS62730 step-down
converter
Low current consumption (14mA in RX
and, 13mA @0dBm TX with step down
converter ON)
Excellent receiver sensitivity, -90 dBm
average in BLE HGM with <1% PER.
3 Low power/sleep modes from 0.5µA
to 270µA.
General-Purpose Timers (One 16-Bit,
Two 8-Bit), 32-kHz Sleep Timer with
Capture
RSSI support
Battery Monitor and Temperature
Sensor
12-Bit ADC with eight channels and
configurable resolution
AES Security Coprocessor
2 USARTs with several serial protocol
support
Watchdog Timer
RoHS Compliant
Shielded package
LGA Footprint
Benefits Summary:
Operating temperature-40 oC to +85 oC
100% RF Tested in production for
repeatable performance
No RF engineering experience
necessary
No protocol experience necessary
Only requires a 2 layer Host PCB
implementation
FCC 15.247, IC RSS-210 and IC RSS-
Gen certified.
Compliant with ETSI EN 300 328
No regulatory “Intentional radiator”
testing required for integrating module
into end product. Simple certification
labeling replaces testing.

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Very Small package size:
11mm x 19mm x 2.5mm
Approximate weight 0.7 grams
1.4. Theory of Operation
The A2541R24A and A2541R24C modules operate in the global 2.4 GHz ISM/SRD frequency
band. They can be used to implement a variety of networks, including point to point, point to
multi-point, peer to peer and mesh networks.
Figure 1 and Figure 2 show the functionality of A2541R24A and A2541R24C, respectively. Both
modules operate in a similar manner except the antenna part where A2541R24A communicates
through a built-in antenna, and A2541R24C communicates through an external antenna
attached to a U.FL antenna port.
Figure 1 The functionality of the A2541R24A, using an internal antenna

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Figure 2 The functionality of the A2541R24C, using an external antenna
The description of the functional blocks shown in Figure 1 and Figure 2 is given as follows:
Antenna
oThe antenna couples energy between the air and the module. The integral
antenna and the external monopole antenna, both centered at 2441.75 MHz,
provide a near omni-directional antenna pattern with high efficiency such that the
application will work in any direction. Note that the end radiation pattern depends
not only on the antenna, but also the ground plane, enclosure and installation
environment.
Matching & Filtering
oThe matching provides the correct loading of the transmit amplifier to achieve the
highest output power as well as the correct loading for the receive LNA to
achieve the best sensitivity.
oFiltering removes spurious signals to comply with regulatory intentional radiator
requirements, provides reduced susceptibility to power supply and digital noise,
and filters out RF and high frequency noise from the communication data and
control link.
TX/RX Chain
oTX/RX chain handles transmitting and receiving of the communication data
based on the radio register settings. It involves the coordination of several blocks
including modulator, demodulator, AGC control, frequency synthesizer and frame
control.
Crystal
oCrystal oscillator provides the necessary clock reference for the whole module
operation. The A2541R24A and A2541R24C modules use two crystals: a 32
MHz crystal and a 32.768 kHz crystal.
Power Management

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oPower management ensures a stable supply for the internal functions, as well as
providing means for a low power sleep mode.
CPU and Memory
oThe 8051 CPU core used in the CC2541 device is a single-cycle 8051-
compatible core. It has three different memory-access buses (SFR, DAT and
CODE/XDATA) with single-cycle access to SFR, DATA, and the main SRAM. It
also includes a debug interface and an 18-input extended interrupt unit.
oThe memory arbiter connects the CPU and DMA controller with the physical
memories and all peripherals through the SFR bus.
oThe 8-KB SRAM maps to the DATA memory space and to parts of the XDATA
memory spaces. This is an ultralow-power SRAM that retains its contents even
when the digital part is powered off.
o256 KB flash block provides in-circuit programmable non-volatile program
memory for the device, and maps into the CODE and XDATA memory spaces. In
addition to holding the program code, it also allows the application to save data
that must be preserved such that it is available after restarting the device.
I/O Controller
oThe I/O controller is responsible for all general-purpose I/O pins. The CPU can
configure whether peripheral modules control certain pins or they are under
software control, and if so, whether they are configured as input or output.
Step-Down Converter (TPS62730)
oThe step-down converter (TPS62730, DC-DC Converter) provides a fixed 2.1V
input voltage to the transceiver chip internally when it is in DC-DC mode and the
module input voltage is above 2.3V.
oBYPASS mode with a typical 30nA current consumption supports the module’s
sleep and low power modes.
oThe step-down converter can be controlled via firmware or by an external signal
on module pin 16. When controlled by firmware the converter is placed into
Bypass mode whenever the CC2541 is in a low-power state, otherwise the
converter is ON (i.e. switching). This helps reduce overall power consumption for
systems operating above 2.1V since the CC2541 device is powered by the
output of the TPS62730 instead of the radio module’s supply pin. That equates to
about 30% reduction in current draw while the radio is in a higher power active
state when operating at 3.0V and about 40% reduction in current when operating
at 3.6V (current reduction is at module input).
oWhen the converter is in DC-DC mode the radio module’s I/O signals will be at
2.1V logic levels, whereas in Bypass mode the I/O will be at logic levels equal to
the module’s supply voltage. This is an important consideration when deciding
whether to force the DC-DC converter into Bypass mode or allow firmware to
cycle between ON and Bypass. In the latter scenario, all devices that interface to
the A2541 must be compatible with the changing logic levels.
oConnections to the step-down converter pins are identified in Figure 3 below. For
brevity, filtering components are not shown.

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Figure 3 Internal connections for TPS62730 Step-Down Converter
Table 1 Approved Antennas
Item
Part Number
Manufacturer
Type
Gain (dBi)
1
Integral part of A2541R24A
Anaren
Integral Antenna
2
2
66089-2406
Anaren
Monopole whip, 6 mm lead
3
3
66089-2430
Anaren
Monopole whip, 30 mm lead
3
1.5. Applications
Bluetooth SMART Systems
Industrial Control and Monitoring
Home/Building Automation
Lighting Systems
Low-Power Wireless Sensor Networks
Sports monitoring, health & wellness

A2541R24x –User’s Manual Page 11 of 36
Release Date 11/22/13
2. Approvals and Usage
The A2541R24A and A2541R24C have been designed to meet many national regulations for
worldwide ISM band use. In particular, the radio modules have been certified to the following
standards.
2.1. Product Approvals
2.1.1. USA (Federal Communications Commission, FCC)
The A2541R24A and A2541R24C modules have been tested to comply with FCC CFR47 Part
15 sub-part C “Intentional Radiators” standard. The modules meet the requirements for modular
transmitter approval as detailed in FCC public notice DA 00-1407 released in June 26, 2000.
The modular transmitter approval eliminates the need to re-perform costly ‘intentional radiator’
testing when submitting an end product for certification.
(15.19a3) The module 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.
Any changes or modifications not expressly approved by the party responsible for compliance
could void the user’s authority to operate the equipment.
2.1.1.1. FCC Labeling Requirements
The A2541R24A and A2541R24C modules have been labeled with their own FCC ID number
and if the FCC ID is not visible when the module is installed inside another device, then the
outside of the finished product into which the module is installed must also display a label
referring to the enclosed module. This exterior label can use wording such as the following:
Contains Transmitter Module FCC ID: X7J-A12062101
-or-
Contains FCC ID: X7J-A12062101
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.

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2.1.1.2. End User Manual
The end user manual should include the following statement:
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:
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.
2.1.1.3. RF Exposure
All transmitters regulated by FCC must comply with RF exposure requirements. OET Bulletin 65
“Evaluating Compliance with FCC Guidelines for Human Exposure to Radio Frequency
Electromagnetic Fields” provides assistance in determining whether proposed or existing
transmitting facilities, operations or devices comply with limits for human exposure to Radio
Frequency (RF) fields adopted by the Federal Communications Commission (FCC). The bulletin
offers guidelines and suggestions for evaluating compliance.
If appropriate, compliance with exposure guidelines for mobile and unlicensed devices can be
accomplished by the use of warning labels and by providing users with information concerning
minimum separation distances from transmitting structures and proper installation of antennas.
The following statement must be included as a CAUTION statement in manuals and OEM
products to alert users of FCC RF Exposure compliance:
To satisfy FCC requirements the antenna used with this transmitter must not be co-located or
operating in conjunction with any other antenna or transmitter except as permitted by FCC multi-
transmitter procedures.
2.1.2. Canada (Industry Canada, IC)
The A2541R24A and A2541R24C modules have been certified for use in Canada under
Industry Canada (IC) Radio Standards Specification (RSS) RSS-210 and RSS-Gen.

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From section 3.2 RSS-Gen, Issue 3, December 2010, Modular Approval for Category I
Equipment or Category II Equipment:
“Modular approval permits the installation of the same module in a host device or multiple host
devices without the need to recertify the device. Equipment certification for a modular device
may be sought for either Category I equipment or Category II equipment.
Transmitters designed as modules for the installation in a host device may obtain equipment
certification as a modular device provided that the applicable RSS is met and the following
conditions in this section are met.”
In section 7.1.2 Transmitter Antenna, it has been mentioned that the user manuals for
transmitters shall display the following notice in a conspicuous location:
Notice: Under Industry Canada regulations, this radio transmitter may only operate using an
antenna of a type and maximum (or lesser) gain approved for the transmitter by Industry
Canada. To reduce potential radio interference to other users, the antenna type and its gain
should be so chosen that the equivalent isotropically radiated power (e.i.r.p.) is not more than
that necessary for successful communication.
Avis: Sous la réglementation d'Industrie Canada, ce transmetteur radio ne peut fonctionner
qu’en utilisant seulement une antenne d'un type et d’un maximum (ou moins) de gain approuvé
pour l'émetteur par Industrie Canada. Pour réduire des potentielles interférences radio pour les
autres utilisateurs, le type d'antenne et son gain doivent être choisis de sorte que la puissance
isotrope rayonnée équivalente (PIRE) ne dépasse pas ce qui est nécessaire pour une
communication réussie.

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In section 7.1.2 Transmitter Antenna, it has been mentioned that the user manuals for
transmitters equipped with detachable antennas shall also contain the following notice in a
conspicuous location:
Notice: This radio transmitter (IC: 8975A-A12062101) has been approved by Industry Canada
to operate with the antenna types listed below with the maximum permissible gain and required
antenna impedance for each antenna type indicated. Antenna types not included in this list,
having a gain greater than the maximum gain indicated for that type, are strictly prohibited for
use with this device.
Avis: Cet émetteur radio (IC: 8975A-A12062101) a été approuvé par Industrie Canada pour
fonctionner avec les types d'antennes énumérés ci-dessous avec le gain maximal admissible et
l’impédance d'antenne requise pour chaque type d'antenne indiqué. Les types d'antennes ne
figurant pas dans cette liste, ayant un gain supérieur au gain maximal indiqué pour ce type, sont
strictement interdits pour l'utilisation avec cet appareil.
Item
numéro d'article
Part Number
Référence
Manufacturer
Fabricant
Type
catégorie
Gain (dBi)
Gain
1
Integral part of
A2541R24A
Partie intégrante de
A2541R24A
Anaren
Integral Antenna
antenne intégrée
2
2
66089-2406
Anaren
Monopole whip, 6 mm lead
Antenne monopôle,
longueur 6 mm
3
3
66089-2430
Anaren
Monopole whip, 30 mm lead
Antenne monopôle,
longueur 30 mm
3
2.1.2.1. IC Labeling Requirements
From section 3.2.1 RSS-Gen, Issue 3, December 2010, Labeling Requirements for the Host
Device:
The host device shall be properly labeled to identify the modules within the host device. The
Industry Canada certification label of a module shall be clearly visible at all times when installed
in the host device, otherwise the host device must be labeled to display the Industry Canada
certification number of the module, preceded by the words “Contains transmitter module”, or the
word “Contains”, or similar wording expressing the same meaning.
From section 5.2, RSS-Gen, Issue 3, December 2010, Equipment Certification Numbers and
Labels:
Every unit of Category I radio apparatus certified for marketing and use in Canada shall bear a
permanent label on which is indelibly displayed the model number and Industry Canada
certification number of the equipment model (transmitter, receiver, or inseparable combination

A2541R24x –User’s Manual Page 15 of 36
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thereof). Each model shall be identified by a unique combination of a model number and a
certification number, which are assigned as described below in this section.
The label shall be securely affixed to a permanently attached part of the device, in a location
where it is visible or easily accessible to the user, and shall not be readily detachable. The label
shall be sufficiently durable to remain fully legible and intact on the device in all normal
conditions of use throughout the device’s expected lifetime. These requirements may be met
either by a separate label or nameplate permanently attached to the device or by permanently
imprinting or impressing the label directly onto the device.
The label text shall be legible without the aid of magnification, but is not required to be larger
than 8-point font size. If the device is too small to meet this condition, the label information may
be included in the user manual upon agreement with Industry Canada.
Section 5.2 continues:
The model number is assigned by the applicant and shall be unique to each model of radio
apparatus under that applicant’s responsibility. The model number shall be displayed on the
label preceded by the text: “Model:”, so it appears as follows:
Model: model number assigned by applicant
Label:
Contains/Contient IC: 8975A- A12062101
Notice: This device complies with Industry Canada licence-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
of the device.
Avis: Cet appareil est conforme avec Industrie Canada RSS standard exempts de licence (s).
Son fonctionnement est soumis aux deux conditions suivantes: (1) cet appareil ne peut pas
provoquer d'interférences et (2) cet appareil doit accepter toute interférence, y compris les
interférences qui peuvent causer un mauvais fonctionnement du dispositif.
From section 7.1.4, RSS-Gen, Issue 3, December 2010, Radio Apparatus Containing Digital
Circuits (ICES-003):
“Radio apparatus containing digital circuitry which can function separately from the operation of
a transmitter or an associated transmitter, shall comply with ICES-003. In such cases, the
labeling requirements of the applicable RSS apply, rather than the labelling requirements in
ICES-003.”
For more information see: Industry Canada http://www.ic.gc.ca/

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2.1.2.2. RF Exposure
All transmitters regulated by IC must comply with RF exposure limits as set forth in RSS-102,
Issue 4, section 4, “Exposure Limits”. Furthermore RSS-102, Issue 4, Section 2 “Certification
Requirements”, provides assistance in determining the specific requirements for compliance. If
appropriate, compliance with exposure guidelines for mobile and unlicensed devices can be
accomplished by the use of warning labels and by providing users with information concerning
minimum separation distances from transmitting structures and proper installation of antennas.
The following statement must be included as a CAUTION statement in manuals and OEM
products to alert users of IC RF Exposure compliance:
Notice: To satisfy Industry Canada requirements the antenna used with this transmitter must
not be co-located or operating in conjunction with any other antenna or transmitter except as
permitted by Industry Canada’s multi-transmitter procedures
Avis: Pour satisfaire aux exigences d'Industrie Canada l'antenne utilisée avec cet émetteur ne
doit pas être colocalisée ni de fonctionner en conjonction avec une autre antenne ou un autre
émetteur, sauf dans la mesure permise par les procédures multi-émetteurs de l'Industrie
Canada
2.1.3. Europe (Conformité Européenne, )
The A2541R24A and A2541R24C modules have been certified for use in European countries
covered by ETSI regulations. The following tests have been performed and the module found to
be compliant to the requirements:
Test standard ETSI EN 300 328 V1.7.1 (2006-10)
Maximum Isotropic Radiated Power (Normal and Extreme Conditions)
Maximum e.i.r.p. Spectral Density
Frequency Range (Normal and Extreme Conditions)
Transmitter Spurious Emissions
Receiver Spurious Emissions
Electro-Static Discharge and RF Immunity (ETSI EN 301 489-17)
RF Exposure (ETSI EN 62311:2008)
Safety (IEC 60950-1:2005 and EN 60950-1:2006)
A helpful document that can be used as a starting point in understanding the use of short range
devices (SRD) in Europe is the European Radio Communications Committee (ERC)
Recommendation 70-03 E, downloadable from the European Radio Communications Office
(ERO) http://www.ero.dk.

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The end user is responsible for ensuring compliance with harmonized frequencies and labeling
requirements for each country the end device is marketed and sold.
For more information see:
Radio And Telecommunications Terminal Equipment (R&TTE)
http://ec.europa.eu/enterprise/rtte/index_en.htm
European Conference of Postal and Telecommunications Administrations (CEPT)
http://www.cept.org/
European Telecommunications Standards Institute (ETSI) http://www.etsi.org/
European Radio Communications Office (ERO) http://www.ero.dk/
2.1.4. Bluetooth Special Interest Group (SIG)
The A2541R24A and A2541R24C modules have been certified and listed as Bluetooth smart
devices under the following categories:
2.2. Potential Interference Sources
The radio modules operate in the unlicensed ISM band, in which there are many other
applications e.g. WLAN, Classic Bluetooth and microwave ovens. This can cause interference
that may, in certain conditions, prohibit radio communication.
Some of the most common interferences are listed below:
2.2.1. WLAN
Wireless Local Area Networks (WLANs) are divided into a number of overlapping channels.
Figure 4 below shows the channels used by WLAN; for the US and Canada, only channels 1-13
may be used. Predominantly, channels 1, 6 and 11 are used to achieve non-overlapping
channels. The user is therefore encouraged to select a channel scheme that also has channels
falling in between, or entirely outside, WLAN channels. Using a detection scheme (clear channel
Model Number Type QDID Memo
A2541R24A10 Controller Subsystem B021836 Antenna Module Based on TI's CC2541 transceiver IC and BLE stack
A2541R24C10 Controller Subsystem B021836 Connector Module Based on TI's CC2541 transceiver IC and BLE stack
Controller Subsystem B021836
Host Subsystem B017183
Controller Subsystem B021836
Host Subsystem B017183
A2541R24A20
Antenna Module Based on TI's CC2541 transceiver IC and Emmoco's Software
based on TI's Host Subsystem
A2541R24C20
Connector Module Based on TI's CC2541 transceiver IC and Emmoco's Software
based on TI's Host Subsystem

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assessment) will enable the user to find channels with minimal interference from WLAN devices.
Figure 4 WLAN channels
2.2.2. Classic Bluetooth
Classic Bluetooth divides the 2.402-2.480 GHz band into 79 channels, each of which is 1MHz
wide. However, since Bluetooth changes channels rapidly (up to 1600 times a second), it is
unlikely to cause continuous interference in a specific channel and can be overcome by
implementing a simple acknowledge/retransmit functionality.
2.2.3. Microwave ovens
A typical microwave oven uses a self-oscillating magnetron with a duty cycle below 50%,
because the tube is completely off for half of every AC mains cycle (8.33 ms in 60 Hz countries
and 10 ms in 50 Hz countries). The frequency of the microwave oven changes cyclically within
each AC mains synchronized on period, and is generally not predictable.
The user is encouraged to have packet transmission durations less than half the AC mains
period and implement an acknowledge/retransmit method.
2.2.4. Other Interference
Systems similar to the user’s system may also exist within range and may also be a source of
interference; some typical applications to consider are:
Alarm systems
oThese typically use low duty cycles and are therefore easy to avoid using
acknowledge/retransmit methods
Car alarms (internal motion sensors)
Video surveillance
oThese are typically operated on a fixed channel, determined at installation time
and can be avoided by using clear channel assessment. It may be useful to
change the channel used by the video surveillance equipment also, if possible.

A2541R24x –User’s Manual Page 19 of 36
Release Date 11/22/13
2.2.5. Time critical data
If the user requires specific time critical data throughput that cannot tolerate the delays of
potentially many re-transmissions, the user is encouraged to implement an environment-aware
algorithm that periodically monitors/scans the frequency band and maintains a list of “best
available” channels.

Page 20 of 36 A2541R24x –User’s Manual
Release Date 11/22/13
2.3. Approved Usage
The A2541R24A and A2541R24C modules have been approved for use in the US, Canada and
Europe. The user is encouraged to use minimum power required to establish a link, thus
minimizing interference.
Changes or modifications to the module and/or operation outside the limits are prohibited and
could void the user’s authority to operate the modules.
2.3.1. USA and Canada
Within the USA and Canada, the A2541R24A and A2541R24C modules have been approved
for use as digitally modulated transmitters, for which they conform to the BW (a minimum of 500
kHz 6-dB BW for US, a maximum BW of 0.5% of the carrier frequency for Canada), power
spectral density (max of 8 dBm / 3 kHz), total output power (max of 1W including the antenna
gain) and spurious radiation (harmonics and others including the restricted bands)
requirements.
Table 2 shows approved modulation types and frequencies of operations with the corresponding
maximum output power values and PA_Table register settings. These modules must be
operated at or below the indicated power levels. Using the modules with higher power levels are
prohibited, and will void the user’s authority to operate the modules under current FCC/IC
certification.
Table 3 shows available power levels from the device along with the corresponding PA_Table
register settings. Users are encouraged to use minimum power required to establish a link, thus
minimizing interference and current consumption.
Table 2 Approved Modulation Types and Power Levels for FCC/IC and ETSI
Approved Modulation Types
Frequency band of
operation (MHz)
Max Allowed
Power (dBm)
PA_Table Value
(Hex)
GFSK 2Mbps,500kHz Deviation
2402 - 2480
+1
0xEF
GFSK 2Mbps, 320kHz Deviation
2402 - 2480
+1
0xEF
GFSK 1Mbps, 250kHz Deviation
2402 - 2480
+1
0xEF
GFSK 1Mbps, 160kHz Deviation
2402 - 2480
+1
0xEF
GFSK 250kbps, 160kHz Deviation
2402 - 2480
+1
0xEF
MSK 500kbps
2402 - 2480
+1
0xEF
MSK 250kbps (ETSI only)
2402 - 2480
+1
0xEF