AT10216: Transmitter Test with Remote Start

APPLICATION NOTE
AT10216: Transmitter Test with Remote Start
Atmel ATSAMR21
Description
®
This example uses the Atmel LwMesh network to configure and activate the
ATSAMR21 transmitter remotely. This tool can be used for regulatory testing of
wireless products where test interfaces have been omitted. This example uses two
ATSAMR21 XPRO demo boards; The Commander (CDR) and the Device Under
Test (DUT). The Commander is connected to a terminal application running on a
PC. The DUT is unattached and requires power only. The DUT binary image can
be used as-is on ATSAMR21 products. Support is included for channel selection,
RF-power settings, and antenna diversity control.
Features
• Configure and Activate Transmitter Over the Air
• Designed for FCC Testing
• Continuous Modulated Carrier Output (PRBS)
• Channel and Power Configuration
• No wires required
• Tx LED indicator
• Crystal Trim Adjustment
Atmel-42373A-Transmitter-Test-with-Remote-Start-ApplicationNote_092014
1
Overview
Developers of wireless products need to exhibit regulatory compliance of radio frequency emissions. This tool
was developed to assist in Federal Communications Commission (FCC) and Industry Canada (IC) testing
programs. Wireless consumer products need to be tested as they are sold to the public including antennas and
enclosures. Typically industrial designers omit external connections for conducted testing, debugging, and
external control. The FCC and IC accept radiated testing measurements. Using this tool Test Engineers can
initiate modulated carrier emissions from the ATSAMR21 remotely.
2
Implementation
In test mode the DUT will transmit a continuous modulated carrier wave (PRBS) until it is reset. This example
uses two ATSAMR21 XPRO demo boards; The Commander (CDR) and the Device Under Test (DUT). The
Commander is connected to a terminal application running on a PC. The DUT is unattached and requires DC
power only.
Figure 2-1.
Test Set-up Diagram
The test system has two entities; The Commander (CDR) and the Device Under Test (DUT). The CDR is
connected to a PC running a Terminal Program such as Terra-Term or PuTTY. The serial port settings are
38400/ 8/1/N/N. The CDR relays messages to and from the DUT. All intelligence resides on the DUT. The DUT
image includes a simple menu system that the Test Engineer can use to select Channel, Power, and Antenna
Path used by the DUT. The CDR is also used to initiate the test. Once the test has started the DUT will
continuously radiate modulated carrier (PRBS) signals until it is reset. Reset can be triggered by power cycling
the DUT, or with an external hard reset, if available.
To initiate and configure the system, the DUT and CDR communicate using the LwMesh Protocol and the default
settings in the config.h file. The LwMesh configuration is hardcoded and should work automatically. The DUT
2
AT10216: Transmitter Test with Remote Start [APPLICATION NOTE]
Atmel-42373A-Transmitter-Test-with-Remote-Start-ApplicationNote_092014
stores configuration selections in the Transmitter Information Base (TIB). The default TIB settings are CH 18
(2440MHz), 0dBm (0x07), and Antenna path 1. When the test is started the TIB is written to the transceiver
control registers, the transmitter is keyed and LED0 is lit. Once the test has started the LwMesh link is terminated.
Resetting the DUT resets the TIB and restarts the LwMesh link. The test engineer will have to reconfigure the TIB
for each test run.
2.1
Channel Configuration
Channels range from CH11 to CH26. A channel chart is shown below. Typically, FCC intentional radiation testing
is done on “High, Middle, and Low” channels; CH11, CH18, and CH26. Developers may want to use CH25 as the
high channel to avoid band-edge emissions in the 2483.5-to-2500MHz restricted band.
Table 2-1.
IEEE 802.15.4 Channel Chart
®
ZigBee Channels
DEC
HEX
MHz
11
0x0B
2405
12
0x0C
2410
13
0x0D
2415
14
0x0E
2420
15
0x0F
2425
16
0x10
2430
17
0x11
2435
18
0x12
2440
19
0x13
2445
20
0x14
2450
21
0x15
2455
22
0x16
2460
23
0x17
2465
24
0x18
2470
25
0x19
2475
26
0x1A
2480
AT10216: Transmitter Test with Remote Start [APPLICATION NOTE]
Atmel-42373A-Transmitter-Test-with-Remote-Start-ApplicationNote_092014
3
2.2
Power Configuration
Power can be adjusted from +4dBm to -17dBm. The TIB uses attenuation values defined in the PHY_TX_PWR
Register. See Section 38.2.5.1 of the ATSAMR21 datasheet [5]. More attenuation equals less radiated power.
Table 2-2.
ATSAMR21 Power Chart
TX PWR
2.3
Attenuation
Power
0x00
+4
0x01
+3.7
0x02
+3.4
0x03
+3
0x04
+2.5
0x05
+2
0x06
+1
0x07
0
0x08
-1
0x09
-2
0x0A
-3
0x0B
-4
0x0C
-6
0x0D
-8
0x0E
-12
0x0F
-17
Crystal Trim
The values of XTAL_TRIM can be adjusted using this tool. This feature can be used to characterize and correct
manufacturing tolerances in the 16MHz crystal circuitry. The total range of carrier deviation is 60kHz (25 PPM).
®
System designers should review the Atmel AVR 2067: Crystal Characterization for AVR RF [4] application note
for more details. Also be advised if XTAL_TRIM coefficients are used. They should be loaded during initialization
only and not modified when network stacks are active.
3
Serial Port
The CDR uses the XPRO EDGB embedded debugger as a UART-to-USB converter. To connect the CDR, use
®
the EDGB USB connector and a Micro-B cable. For Windows users, the COM port will be assigned by the PC
operating system. Use the Device Manager control panel to determine which COM port was chosen. The default
settings for the Terminal Program should be 38400/8/1/N.
4
AT10216: Transmitter Test with Remote Start [APPLICATION NOTE]
Atmel-42373A-Transmitter-Test-with-Remote-Start-ApplicationNote_092014
4
User’s Menu
Figure 4-1.
Menu Screen Shot
The menu is a simple 1-level design. This tool was designed for manual incremental adjustments (‘plinking’) by
test engineers. Many adjustments are made by incrementing or decrementing TIB settings. The menu is case
sensitive; UPPER CASE INCREASES, lower case decreases. Also note, several register values are inverted, for
example the “TX_PWR” register is really an attenuator; less value = more RF-power. The Menu uses
conventional orientation for adjustments. Any undefined inputs return the user to the Top Menu.
<Shift> “T” starts the transmitter. The LwMesh link is terminated.
“s” displays the values in the TIB.
<Shift> “C” increments the channel.
“c” decrements the channel.
<Shift> “P” increases RF-power (less attenuation.)
AT10216: Transmitter Test with Remote Start [APPLICATION NOTE]
Atmel-42373A-Transmitter-Test-with-Remote-Start-ApplicationNote_092014
5
“p” decreases RF-power (more attenuation.)
“a” toggles antenna path. ANT1 = SMA, ANT2 = Chip
<Shift> “F” increases the carrier offset
“f” decreases the carrier offset
Any undefined input returns Menu: display.
5
Receiver Testing
Unintentional radiation and immunity be exhibited with the DUT paused at the Menu: prompt. In this state the
receiver is continuously active.
6
7
Caveats
•
This system uses the LwMesh for initial communication between the DUT and the CDR. When the
Transmitter test is activated the LwMesh Link is lost.
•
To avoid address contention, do not power up more than one DUT at a time
•
Use for radiated RF measurements only. CDR cannot link to DUT in conducted test.
Summary
This example will help test engineers with regulatory testing for FCC and IC. This system can be used to exhibit
regulatory compliance of products using Atmel ATSAMR21. The application can be loaded onto most
ATSAMR21 products. The remote start features allows products to be tested with enclosures and free from wired
connections.
8
References
®
[1] Atmel AVR 2130: Lightweight Mesh Developer Guide
®
[2] IEEE Std 802.15.4™-2006
[3] FCC CFR-2009-title47-vol1-part15
[4] Atmel AVR2067: Crystal Characterization for AVR RF
[5] Atmel SAM R21E/ SAM R21G Datasheet
6
AT10216: Transmitter Test with Remote Start [APPLICATION NOTE]
Atmel-42373A-Transmitter-Test-with-Remote-Start-ApplicationNote_092014
9
Revision History
Doc Rev.
Date
42373A
09/2014
Comments
Initial document release.
AT10216: Transmitter Test with Remote Start [APPLICATION NOTE]
Atmel-42373A-Transmitter-Test-with-Remote-Start-ApplicationNote_092014
7
Atmel Corporation
1600 Technology Drive, San Jose, CA 95110 USA
T: (+1)(408) 441.0311
F: (+1)(408) 436.4200
│
www.atmel.com
© 2014 Atmel Corporation. / Rev.:Atmel-42373A-Transmitter-Test-with-Remote-Start-ApplicationNote_092014.
Atmel®, Atmel logo and combinations thereof, AVR®, Enabling Unlimited Possibilities®, and others are registered trademarks or trademarks of Atmel Corporation in U.S.
®
and other countries. Windows is a registered trademark of Microsoft Corporation in U.S. and or other countries. Other terms and product names may be
trademarks of others.
DISCLAIMER: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any intellectual property right
is granted by this document or in connection with the sale of Atmel products. EXCEPT AS SET FORTH IN THE ATMEL TERMS AND CONDITIONS OF SALES LOCATED ON THE ATMEL
WEBSITE, ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS, IMPLIED OR STATUTORY WARRANTY RELATING TO ITS PRODUCTS INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. IN NO EVENT SHALL ATMEL BE
LIABLE FOR ANY DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE, SPECIAL OR INCIDENTAL DAMAGES (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS AND
PROFITS, BUSINESS INTERRUPTION, OR LOSS OF INFORMATION) ARISING OUT OF THE USE OR INABILITY TO USE THIS DOCUMENT, EVEN IF ATMEL HAS BEEN ADVISED
OF THE POSSIBILITY OF SUCH DAMAGES. Atmel makes no representations or warranties with respect to the accuracy or completeness of the contents of this document and reserves
the right to make changes to specifications and products descriptions at any time without notice. Atmel does not make any commitment to update the information contained herein. Unless
specifically provided otherwise, Atmel products are not suitable for, and shall not be used in, automotive applications. Atmel products are not intended, authorized, or warranted for use
as components in applications intended to support or sustain life.
8
SAFETY-CRITICAL, MILITARY, AND AUTOMOTIVE APPLICATIONS DISCLAIMER: Atmel products are not designed for and will not be used in connection with any applications where
the failure of such products would reasonably be expected to result in significant personal injury or death (“Safety-Critical Applications”) without an Atmel officer's specific written consent.
Safety-Critical Applications include, without limitation, life support devices and systems, equipment or systems for the operation of nuclear facilities and weapons systems. Atmel products
are not designed nor intended for use in military or aerospace applications or environments unless specifically designated by Atmel as military-grade. Atmel products are not designed nor
intended for
use in automotive applications unless specifically designated by Atmel as automotive-grade.
Atmel-42373A-Transmitter-Test-with-Remote-Start-ApplicationNote_092014
AT10216: Transmitter Test with Remote Start [APPLICATION NOTE]

Download Report