u-blox XPLR-AOA Explorer Kits Bluetooth Indoor Direction Finding User Guide

: June 9, 2024
: u-blox

Table of Contents

XPLR-AOA Explorer Kits Bluetooth Indoor Direction Finding
References
Read User Manual Online (PDF format)
Download This Manual (PDF format)

XPLR-AOA Explorer Kits Bluetooth Indoor Direction Finding

XPLR-AOA explorer kits
Bluetooth indoor direction finding
User guide

Abstract
This document describes the XPLR-AOA explorer kits for evaluating Bluetooth 5.1 direction finding and indoor positioning use cases using Angle-of-Arrival methodology. It serves as a practical guide that explains how the u-blox modules and software included in the kit are used to explore directionfinding tags and anchor nodes. The kit contents, setup, configuration, and operation are described.

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XPLR-AOA explorer kits – User guide

Document information

Title Subtitle Document type Document number Revision and date Disclosure restriction

XPLR-AOA explorer kits Bluetooth indoor direction finding User guide UBX-21004616 R08 C1 – Public

7-Apr-2022

This document applies to the following products:
Product name NINA-B4 XPLR-AOA-1 XPLR-AOA-2

u-blox or third parties may hold intellectual property rights in the products, names, logos and designs included in this document. Copying, reproduction, modification or disclosure to third parties of this document or any part thereof is only permitted with the express written permission of u-blox. The information contained herein is provided “as is” and u-blox assumes no liability for its use. No warranty, either express or implied, is given, including but not limited to, with respect to the accuracy, correctness, reliability and fitness for a particular purpose of the information. This document may be revised by u-blox at any time without notice. For the most recent documents, visit www.u-blox.com. Copyright © u-blox AG.

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Contents
Document information ……………………………………………………………………………………………………………….. 2 Contents ………………………………………………………………………………………………………………………………………. 3 1 Product description ……………………………………………………………………………………………………………… 5
1.1 Kit includes ………………………………………………………………………………………………………………………………… 6 1.2 Evaluation software…………………………………………………………………………………………………………………… 6 1.3 System requirements ……………………………………………………………………………………………………………….. 6 1.4 Ordering information…………………………………………………………………………………………………………………. 6
2 Quick start guide…………………………………………………………………………………………………………………… 7
2.1 C211 anchor setup ……………………………………………………………………………………………………………………. 7 2.2 C209 tag set up …………………………………………………………………………………………………………………………. 7 2.3 Wireless anchor-to-host setup …………………………………………………………………………………………………. 7
3 Bluetooth direction finding …………………………………………………………………………………………………. 8
3.1 Technology ………………………………………………………………………………………………………………………………… 8 3.1.1 Angle of Arrival (AoA) …………………………………………………………………………………………………………. 8 3.1.2 Angle of Departure (AoD) …………………………………………………………………………………………………… 9 3.1.3 Angles of measurement …………………………………………………………………………………………………….. 9
4 XPLR-AOA anchor nodes and tags ………………………………………………………………………………….. 10
4.1 Introduction………………………………………………………………………………………………………………………………10 4.2 Overview ……………………………………………………………………………………………………………………………………10 4.3 C211 anchor nodes …………………………………………………………………………………………………………………..11
4.3.1 Overview ……………………………………………………………………………………………………………………………11 4.3.2 Connectors ………………………………………………………………………………………………………………………..12 4.3.3 Flashing …………………………………………………………………………………………………………………………….16 4.3.4 Configuring the board ……………………………………………………………………………………………………….17 4.4 C209 tags …………………………………………………………………………………………………………………………………18 4.4.1 Overview ……………………………………………………………………………………………………………………………18 4.4.2 Software and flashing……………………………………………………………………………………………………….19
5 System setup ……………………………………………………………………………………………………………………… 21
5.1 Anchor node configuration……………………………………………………………………………………………………….21 5.2 Tag configuration……………………………………………………………………………………………………………………..21
5.2.1 Configuring advertising interval ……………………………………………………………………………………….21 5.2.2 Enabling/disabling advertising …………………………………………………………………………………………22 5.3 Restore Eddystone Instance ID ………………………………………………………………………………………………..22
6 Running system …………………………………………………………………………………………………………………. 23 Appendix ……………………………………………………………………………………………………………………………………. 25 A Anchor node AT commands ……………………………………………………………………………………………… 25
A.1 Direction finding enable +UDFENABLE ……………………………………………………………………………………25 A.1.1 Description ………………………………………………………………………………………………………………………..25 A.1.2 Syntax ……………………………………………………………………………………………………………………………….25 A.1.3 Defined values …………………………………………………………………………………………………………………..25

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XPLR-AOA explorer kits – User guide
A.2 Direction finding filter +UDFFILT …………………………………………………………………………………………….25 A.2.1 Description ………………………………………………………………………………………………………………………..25 A.2.2 Syntax ……………………………………………………………………………………………………………………………….25 A.2.3 Defined values …………………………………………………………………………………………………………………..26 A.2.4 Notes …………………………………………………………………………………………………………………………………26
A.3 Configure direction finding +UDFCFG ……………………………………………………………………………………..26 A.3.1 Description ………………………………………………………………………………………………………………………..26 A.3.2 Syntax ……………………………………………………………………………………………………………………………….26 A.3.3 Defined values …………………………………………………………………………………………………………………..27
A.4 Angle calculation event +UUDF………………………………………………………………………………………………..28 A.4.1 Description ………………………………………………………………………………………………………………………..28 A.4.2 Syntax ……………………………………………………………………………………………………………………………….28 A.4.3 Defined values …………………………………………………………………………………………………………………..28
A.5 RS232 setting +UMRS……………………………………………………………………………………………………………..28 A.5.1 Description ………………………………………………………………………………………………………………………..28 A.5.2 Syntax ……………………………………………………………………………………………………………………………….28 A.5.3 Defined values …………………………………………………………………………………………………………………..28 A.5.4 Notes …………………………………………………………………………………………………………………………………29
A.6 Other supported AT commands ………………………………………………………………………………………………29
B Glossary ………………………………………………………………………………………………………………………………. 30 C Limitations………………………………………………………………………………………………………………………….. 30 D C209 schematics ……………………………………………………………………………………………………………….. 31 Related documentation …………………………………………………………………………………………………………… 32 Revision history ………………………………………………………………………………………………………………………… 33 Contact………………………………………………………………………………………………………………………………………. 34

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1 Product description

A Bluetooth “tag” is a small, thin device that can attached to any object to track its whereabouts. An “anchor node” calculates the position of the tag. Bluetooth tags can attach to keys, wallets, purses, and other personal property.
u-blox direction finding solutions that leverage this Bluetooth direction finding technology can be evaluated using two separate explorer kits, as described in Table 1.

Model XPLR-AOA-1

Order code XPLR-AOA-1

XPLR-AOA-2 XPLR-AOA-2

Description
Bluetooth 5.1 direction finding explorer kit for evaluating Bluetooth 5.1 direction finding using Angle-of-Arrival methodology. The kit includes a single C211 application board and one C209 tag:
· C211 application boards include a NINA-B411 module and an antenna array that represents the anchor node for direction finding, using Angle-of-Arrival methodology. u-connectLocate direction finding software installed on NINA-B411 delivers angle information for tracked tags to a listening host.
· C209 tags are based on the open CPU NINA-B406 module variant. The tags run on custom tag software that advertise Eddystone beacons with appended with Constant Tone Extensions (CTE). The CTE data is used by C211 application board to calculate the position of the C209 tag.
Bluetooth 5.1 direction finding explorer kit for evaluating and developing indoor positioning use cases, using Angle-of-Arrival methodology. The kit includes a four C211 application boards, four C209 tags and positioning engine client software:
· C211 application boards include a NINA-B411 module and an antenna array that represents the anchor node for direction finding using Angle-of-Arrival methodology. u-connectLocate direction finding software installed on NINA-B411 delivers angle information for tracked tags to a listening host.
· C209 tags are based on the open CPU NINA-B406 module variant. The tags run on custom tag software that advertise Eddystone beacons with appended with Constant Tone Extensions (CTE). The CTE data is used by C211 application board to calculate the position of the C209 tag.

Table 1: u-blox direction-finding explorer kits and ordering codes
For further information about the positioning engine client software for Windows, see also the
indoor positioning guide [2].

Figure 1: u-blox direction-finding explorer kits comprising C211 application board(s) and C209 tag(s)

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1.1 Kit includes
XPLR-AOA-1 direction finding explorer kit for out-of-the-box AoA evaluation includes:
· C211 antenna board with NINA-B411 Bluetooth LE module · C209 tag with NINA-B406 Bluetooth LE module · u-connectLocate direction finding software (from u-blox.com) · C209 tag software example (from Github)

XPLR-AOA-2 indoor positioning explorer kit for out-of-the-box evaluation of indoor positioning includes:
· Four C211 antenna boards with NINA-B411 module · Four C209 tags with NINA-B406 module · u-connectLocate direction finding software (from u-blox.com) · C209 tag software example (from Github) · Positioning engine software example to run on a PC

1.2 Evaluation software
Several evaluation packages are available:
· u-connectLocate delivers angle information for tracked tags to a listening host. Customers install u-connectLocate software on the NINA B411 module mounted on the C211 integration board. C211 integration boards are delivered with bootloader software only.
· s-center software Bluetooth and Wi-Fi evaluation software provides a powerful and easy-to-use tool for evaluating, configuring, and testing u-blox short range modules
· Sample positioning-engine client that runs on a local Windows workstation (XPLR-AOA-2 only)

1.3 System requirements
· PC with USB interface · Operating system: Windows 7 onwards, Linux, or Mac OS

1.4 Ordering information
Product name XPLR-AOA-1 (with active C211 LED array) XPLR-AOA-1 (without active C211 LED array) XPLR-AOA-2 (with active C211 LED array) XPLR-AOA-2 (without active C211 LED array)

Ordering code XPLR-AOA-1-00 XPLR-AOA-1-01 XPLR-AOA-2-00 XPLR-AOA-2-01

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2 Quick start guide
Use this to set up the C211 anchor and C209 tags included in the XPLR-AOA kits.
2.1 C211 anchor setup
Use the following procedure to set up the C211 anchor boards.
1. Connect the anchor to your computer using a USB-A to Micro-B cable. Drivers for the onboard FTDI USB-to-UART converter are normally installed automatically, but otherwise download and install these directly from the FTDI website [20]. The serial port is visible in the device manager when it is successfully installed.
2. Flash the u-connectLocate software using the bundled (Windows only) newtmgr executable or s-center [7]. Alternatively, use the Newt Manager Guide [10] to install the newtmgr application tool for MAC OS, Linux, and Windows. See also Flashing.
3. Start a terminal emulator (Tera Term or similar) and open the port with the settings described in Configuring the board.
4. Restart the board using the Reset button. A +STARTUP event is shown in your terminal emulator when the board is ready to accept AT commands and deliver direction finding angle calculation events. See also Angle calculation event +UUDF.
2.2 C209 tag set up
Use the following procedure to set up the C209 tags.
1. Connect the anchor to your computer using a USB-A to Micro-B cable. Drivers for the onboard FTDI USB-to-UART converter are normally installed automatically, but otherwise download and install these directly from from the FTDI website [20]. The serial port is visible in the device manager when it is successfully installed.
2. Flash the C209 tag software available from the C209 github repo [13] using command line tools or s-center [7], as described in Software and flashing. After the tag is flashed, the LED on the C209 tag blinks blue rapidly to show that the tag is now sending direction-finding enabled advertisements. You should now see angle calculation events over the UART of the C211.
3. You can now switch to power the C209 tag using a CR2032 battery (not included).
2.3 Wireless anchor-to-host setup
To set up wireless communication from the C211 anchor to a host, see EVK- ODIN-W2 wireless gateway configuration. The setup requires one EVK-ODIN-W2 per C211 anchor node.

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3 Bluetooth direction finding
Bluetooth direction finding provides a relatively inexpensive and flexible approach to developing location-related applications for both in indoor and outdoor environments. Examples of applications for which Bluetooth direction finding technology is most suitable include: · Asset tracking · Navigation · Wayfinding · Proximity/Direction detection
3.1 Technology
Bluetooth direction finding can be implemented using two different methods, Angle of Arrival (AoA) and of Departure (AoD). In each case, protocol-specific control information and user data, transmitted as Bluetooth Protocol Data Units (PDU), are appended with direction-finding data known as Constant Tone Extension (CTE). This additional direction-finding data is appended to the end of the packages, as shown in Figure 2.
Figure 2: Bluetooth PDU with Constant Tone Extension
3.1.1 Angle of Arrival (AoA)
In AoA systems, the receiver has an antenna array with multiple antennas. The receiver calculates the phase shift between these antennas to detect the direction of the tag that it is tracking. An overview of a system using this method of direction finding is shown in Figure 3.

Figure 3: Angle of Arrival (AoA) system architecture

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3.1.2 Angle of Departure (AoD)
In AoD systems, the transmitter has multiple antennas. The receiver calculates the phase difference between these antennas to determine the direction to the transmitter. By using this data in combination with angle data from other transmitters, the receiver can estimate its position. An overview of a system using this method of direction finding is shown in in Figure 4.

Figure 4: Angle of Departure (AoD) system architecture
3.1.3 Angles of measurement
In both AoA and AoD systems, the reported angles of the azimuth and elevation measurements are compared against a reference plane, as shown in Figure 5.

Figure 5: Azimuth and elevation angles
For further information about Bluetooth direction finding, see the u-blox webinar “Bluetooth for High Precision Indoor Positioning” available on the u-blox webinar page [8] and Bluetooth SIG technical overview [1].

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4 XPLR-AOA anchor nodes and tags
4.1 Introduction
Both XPLR-AOA-1 and XPLR-AOA-2 explorer kits include both Bluetooth anchor nodes and tags.
Although this chapter generally describes these nodes and tags in the context of the XPLR-AOA-1
direction finding system, the concepts it describes are equally applicable to the XPLR-AOA-2 indoor positioning explorer kit. For information about the XPLR-AOA-2 positioning engine, setup, and configuration, see also the indoor positioning application note [2].
4.2 Overview
u-blox direction finding solutions are comprised of C211 anchor nodes C209 tags, as shown in Figure 6. See also Kit includes. u-blox direction-finding solution supports the Angle of Arrival (AoA) methodology.
C211 anchor nodes are based on NINA-B4 modules that include support for direction finding. Anchor nodes are based on NINA-B411 u-connectXpress functionality, whereas C209 tags are based on NINA-B406 open CPU architecture. For more information about these short-range Bluetooth modules, see also the respective data sheets [14][15] and product pages [2].
Figure 6 shows several anchor nodes and a host that uses the combined information from the anchor nodes to calculate the position of the tag. For simple direction finding one anchor node is sufficient.

Figure 6: XPLR-AOA direction-finding solution showing four anchor points tracking a single tag

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4.3 C211 anchor nodes
4.3.1 Overview
C211 application boards are equipped with a NINA-B411 module and an antenna array. These boards fulfill the role of the anchor node in the XPLR-AOA direction-finding solutions. Anchor nodes run AT command-based u-connectLocate direction finding software, which delivers AoA data for tracked tags to a listening host. Data is transmitted to the host as events over the NINA-B411 UART interface. See also Anchor node AT commands. · C211 has an array of five antennas that are used to detect the phase shift for the direction finding
in both horizontal and vertical levels. · C211 also has an LED array in the form of a cross. The LEDs indicate the direction of tracked
beacons. In instances where the anchor node tracks several beacons, the LED array tracks the first C209 tag that is discovered.
Some product variants do not include the LED cross on the C211 application board, which is part
of the XPLR-AOA kits: o XPLR-AOA-1-00 C211 has an active LED array o XPLR- AOA-1-01 C211 does not have an active LED array o XPLR-AOA-2-00 C211 has an active LED array o XPLR-AOA-2-01 C211 does not have an active LED array Figure 7 shows an overview image of the C211 antenna side.
Figure 7: C211 antenna side
The C211 board dimensions are 115 (h) x 114 (w) mm.
C211 schematics are proprietary and not shared.

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4.3.2 Connectors 4.3.2.1 UART
The UART connection must be configured for USB connection with jumpers connecting pins 3 to 5 and 4 to 6 on connector J5, as shown in Figure 8.
Figure 8: Jumper settings for UART connection over USB
4.3.2.2 Buttons
The C211 board has three buttons on one edge of the board: · RESET: Resets (reboot) the board · SW1: Initiates factory reset of the board settings: Hold down SW1 during board reset and hold for
10 seconds to trigger a factory reset. · SW2: Enters the software download mode: Hold down SW2 during board reset to enter the
download mode. See also Flashing.
4.3.2.3 Arduino interface
C211 boards contain an Arduino compatible interface that can be used to connect, for example, an ODIN-W2 EVK to enable wireless communication over UDP. For further information about UDP, see the u-connectXpress software user guide [17].

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The Arduino connectors, J1, J3 and J4, are shown in Figure 9.

Figure 9: C211 with Arduino connectors marked
4.3.2.3.1 Pinout
The pinout of the Arduino compatible connectors is described in EVK-ODIN-W2 wireless gateway configuration.

Connector Pin Name Description

J1

1

NC

Not connected

2

IOREF IO reference voltage

3

RESET Reset

4

3V3

Regulated 3.3 V net. This net is supplied by the board and is always powered as long as a power source is connected.

5

5V0

5 V supply

6

GND

Ground

7

GND

Ground

8

VIN

External power supply via ODIN-W2

J3

1

NC

Not connected

2

NC

Not connected

3

RXD

Can be connected to NINA-B411 GPIO_22/UART_TXD by populating jumper J5 pin [1-3]

4

NC

Not connected

5

NC

Not connected

6

D5

Not Connected. Can be connected to NINA-B411 GPIO_32 by populating position R68.

7

NC

Not connected

8

NC

Not connected

J4

1

TXD/D8 Can be connected to NINA-B411 GPIO_23/UART_RXD by populating jumper J5 pin [2-4]

Not Connected. Can be connected to NINA-B411 GPIO_33 by populating position R70.

2

D9

Not Connected. Can be connected to NINA-B411 GPIO_46 by populating position R69.

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Connector Pin Name Description

3

NC

4

NC

5

NC

6

D13

7

GND

8

NC

9

SDA

10 SCL

Not connected Not connected Not connected Not Connected. Can be connected to NINA-B411 GPIO_45 by populating position R67 Ground Not connected Not Connected. Can be connected to NINA-B411 GPIO_4/I2C SDA by populating position R66. Not Connected. Can be connected to NINA-B411 GPIO_5/I2C SDL by populating position R65.

Table 2: Pin out of Arduino connectors

4.3.2.3.2 Connecting EVK-ODIN-W2 for wireless communication

When connecting an EVK-ODIN-W2 evaluation kit for wireless communication, you need to redirect the TX channel from the C211 anchor to EKV-ODIN-W2 by modifying the jumpers on the J5 connector, as shown in Figure 10. This connects the UART TX pin on the C211 to UART1 RX on the EVK-ODIN-W2. See also the EVK-ODIN-W2 user guide [16].

Figure 10: Redirecting C211 UART TX to Arduino connector
4.3.2.3.3 Power supply
When mounting an ODIN-W2 EVK, the application board is powered through the ODIN-W2 EVK USB contact. No other power supply to the C211 board is needed.
4.3.2.4 EVK-ODIN-W2 wireless gateway configuration
For C211 wireless communication though an EVK-ODIN-W2, the EVK must first be configured as a wireless UDP gateway. In this configuration the EVK can:
· Connect to a Wi-Fi network · Automatically connect to the UDP server at “server_ip” and “udp_port” · Startup in data mode · Set the UART to 1 Mbps with no flow control

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1. Enter the following commands to setup EVK-ODIN-W2 as a wireless UDP gateway:
Replace the “ssid”, “password”, “server_ip” and “udp_port” with suitable values for your
network.
AT+UWSC=0,0,1 AT+UWSC=0,2,”ssid” AT+UWSC=0,5,2 AT+UWSC=0,8,”password” AT+UWSC=0,100,2 AT+UWSC=0,107,0 AT+UWSC=0,300,0 AT+UWSC=0,301,1 AT+UWSCA=0,1 AT+UWSCA=0,3 AT+UDDRP=0,”udp://server_ip:udp_port/”,2 AT+UMSM=1 AT+UMRS=1000000,2,8,1,1,0 AT&W AT+CPWROFF
The above settings start up the module in data mode and change the UART settings to 1 Mbps
with no flow control. If you need to modify settings, open the COM port in s-center with 1 Mbps speed and no flow control, and then press the “AT Mode” button to get back into command mode. For more information, see the u-connectXpress AT commands manual [5].
Note that some commands shown above are not valid in all ODIN-W2 software versions. If any
of these commands return an error, use s-center to upgrade your ODIN-W2 EVK to software version 8.0 or later. See also the s-center user guide [18].
For other configuration possibilities see the u-connectXpress AT commands manual [5] and u-connectXpress software user guide [17].
2. After the configuration it is necessary to remove jumpers J13 and J22, as shown in Figure 13. These jumpers select UART1/UART3 on the EVK-ODIN-W2 and direct the UART signals to the Arduino-compatible interface.

Figure 11: UART selection jumpers to be removed on ODIN-W2 EVK

3. On C211, set the UART baud rate and other interface settings to 1 Mbps, with no flow control:
AT+UMRS=1000000,0 AT&W AT+CPWROFF

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4.3.3 Flashing
Other than the bootloader, C211 boards are delivered without software.
4.3.3.1 Command line flashing
Follow the procedure outlined below to flash the board over the UART connection.
1. Download the u-connectLocate software container from [19]. 2. Flash the u-connectLocate software using the bundled (Windows only) newtmgr executable.
Alternatively, use the Newt Manager Guide [10] to install the newtmgr application tool for MAC OS, Linux, and Windows. 3. Use Newt Manager to install u-connectLocate on the NINA-B411 module:
newtmgr –conntype=serial –connstring=”COMXX,baud=115200″ image upload <binary image>
4. Press the reset button to reset the application board or reset it with newtmgr:
newtmgr –conntype=serial –connstring=”COMXX,baud=115200″ reset
As there is no software to boot during the initial startup, the NINA-B411 module automatically
enters the software download mode. In future updates of NINA-B41 u-connectLocate software the bootloader must be manually set in software download mode by pressing the SW2 button during board reset. The board is reset by inserting the USB cable or by clicking the RESET button. See also Figure 15.
4.3.3.2 Flashing using s-center
The C211 anchors can also be flashed over the UART using s-center [7].
This requires s-center 6.1 or later.
Follow the flashing procedure outlined below when using s-center:
1. Download and unzip the u-connectLocate software container as described in Command line flashing.
2. Open s-center on the correct COM port once the module is in software download mode. 3. Select Software Update. 4. In the “Software Update” dialogue select the binary file in the software container, as shown in
Figure 12. Make sure the flashing speed is set to 115200. 5. Press Update.

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Figure 12: Updating the software on the C211 board using s-center
4.3.4 Configuring the board
When connecting to the USB port on the C211, a serial port (COM port on Windows) is available on the host. Connect the COM port to a terminal emulator or use the s-center tool [7] to initially configure the port settings:
· 115200 kbps · 8 data bits, no parity, 1 stop bit (8N1) · Flow control enabled using RTS/CTS
Having configured the COM port, configure the C211 using AT commands. The appropriate AT commands for configuring direction finding through the C211 anchor nodes are described in Appendix A.
Although s-center does not support specific direction-finding AT commands using buttons, it is
possible to configure the COM port as a terminal for use with AT commands.
Due to the large amount of data received over the UART it may be advisable to increase the baud rate over the UART interface. In the following command example, the baud rate is set to 1 Mbps using the command AT+UMRS.
AT+UMRS=1000000,1 AT&W AT+CPWROFF

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4.4 C209 tags
4.4.1 Overview
C209 tags are based on the open CPU NINA-B406 module variant. The tags run on custom tag software that advertises as an Eddystone beacon with a Constant Tone Extension added to the advertising packets. This CTE is used by the u-connectLocate direction finding software that runs on the C211 application board to calculate the Angle of Arrival.
The namespace included in the transmitted Eddystone-UID beacon is 0x4E494E412D4234544147and the instance id is based on the MAC address of the NINA-B406 found on the module QR code label. See also Restore Eddystone Instance ID.
C209 tags are powered by a single CR2032 battery (not included) or through the USB connector.
C209 tags includes a versatile sensor node that comprises several sensors for use in a multitude of different applications. The on-board sensors include:
· LIS2DW12 accelerometer · APDS-9306 ambient light sensor · BME280 humidity, pressure, and temperature sensor
The main components of any C209 tag are shown in Figure 13.

Figure 13: C209 main functional components
The important pin definitions on the C209 application board are described in Table 3.

No. GPIO_1 GPIO_2

Name RED LIS_INT

GPIO_7 GPIO_8 GPIO_18

GREEN BLUE SWITCH_2

I/O Description

Remarks

O

RED system status signal

Active low

I

Interrupt signal from Ambient Light

Sensor

O

GREEN system status signal

Active low

O

BLUE system status signal

Active low

I

Switch_2 button

Active low

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No.

Name

I/O Description

Remarks

GPIO_20 UART_RTS O

UART request to send control signal Used only when hardware flow control is enabled

GPIO_21 UART_CTS I

UART clear to send control signal

Used only when hardware flow control is enabled

GPIO_22 UART_TXD O

UART data output

GPIO_23 UART_RXD I

UART data input

GPIO_42 LIS_INT

I

Interrupt signal from accelerometer

Table 3: Important pin definitions on the C209
For more information about programming the module, see also the NINA-B4 system integration manual [6] and NINA-B40 data sheet [14]. See also C209 schematics.

Although the sensors on the C209 application board are not used in the latest direction-finding
tag software from u-blox, the sensors can be utilized in any customer application.

4.4.2 Software and flashing
C209 tags are delivered with bootloader software only and do not include the tag software (available from Github [13]) needed for the device to advertise Bluetooth beacons to C211 anchor nodes.
The bootloader on C209 tags is different than that supplied on C211anchor nodes, and the nrfutil [11] flashing tool is needed to install software via UART and the boot loader.
u-blox C209 tag software can be installed using the DFU bootloader or an external debugger. Precompiled packages for each installation option are available from the u-blox C209 software repository [13].
4.4.2.1 Installing tag software with the DFU bootloader over the command line
Install C209 tag software with the pre-flashed DFU bootloader on NINA-B406:
1. Download and install the nrfutil flashing tool from the Nordic Github repository [12]. 2. Download and unpack the c209_aoa_tag_for_dfu_boot.zip file from the u-blox C209 software
repository using this direct link, or go to the “Releases” section via the main github repository page [13]. The unpacked file includes the app.zip file used for the installation. 3. Press and hold the SW2 button on the C209 while resetting the board (by inserting the USB cable or clicking the RESET button) to set the bootloader in “download” mode. See also Figure 15. 4. Use the following command to install the C209 tag software using nfutil:
nrfutil dfu serial -pkg app.zip -p COMXX -b 115200 -fc 1
Replace COMXX with the appropriate COM port for your system.
4.4.2.2 Installing tag software with the DFU bootloader using s-center
The C209 tags can also be flashed over the UART using s-center [7].
This requires s-center 6.1 or later.
Follow the flashing procedure outlined below when using s-center:
1. Download and unzip the u-connectLocate sofware container, as described in Installing tag software with the DFU bootloader over the command line.
2. Open s-center on the correct COM port once the module is in SW download mode. 3. Select Software Update. 4. In the “Software Update” dialogue, select the app.zip file from the software container, as shown
in Figure 14. Make sure the flashing speed is set to 115200. 5. Press Update.

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Figure 14: Updating the SW on the C209 board via s-center
4.4.2.3 Installing tag software using a debugger
C209 tag software can also be installed using a debugger connected through the J10 10-pin contact on the PCB. Install C209 tag software with the pre-flashed DFU bootloader on NINA-B406: 1. Download the c209_aoa_tag_no_boot_required.zip from the u-blox C209 software
repository [13]. 2. Unzip the downloaded file. 3. Connect the debugger to the 10-pin contact on the C209. 4. Flash the hex file from the zip using your debugger.

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5 System setup
5.1 Anchor node configuration
By default, the C211 Anchor Point comes pre-configured to track all u-blox tags. The u-blox tags advertise with the Eddystone namespace 0x4E494E412D4234544147, which is default on the C211 to track. So, if you are only using the u-blox supplied XPLR-AOA kit, no configuration is needed.
Each anchor node can be configured with beacons to track. An example for how to set up the anchor to track two tags is shown below:
AT+UDFFILT=1,2,”6E616D65737061636578″ At+UDFFILT=2,2,”CCF9578E0D8A”,”CCF9578E0D8B” AT+UDFENABLE=1 (Tracking is enabled by default, so this is optional) These commands set up the anchor to track the two tags with the given MAC addresses in the Eddystone name space (6E616D65737061636578) used by the tags.
The sequence described above reflects the most simplistic use case. Further configuration is possible using the AT+UDFCFG command. See also Configuration direction finding +UDFCFG.
The settings shall be saved using the AT&W command, followed by a restart (AT+CPWROFF).
5.2 Tag configuration
5.2.1 Configuring advertising interval
Press the SW2 button on the C209 to change the advertising interval. The default interval at startup is 20 milliseconds
When SW2 is pressed, the advertising interval cycles through [20, 100, 1000] milliseconds. For best performance, it is advisable to use the default 20 ms advertising interval.

Figure 15: C209 with cover and buttons indicated

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C209 tags are simply configured over the UART interface using AT commands. The AT commands that can be used to configure the interface are described in Table 4.

Command AT+UMLA=1 AT+GMM AT+TXPWR=

Description Read Local MAC address Read the model identifier, NINA-B4-TAG

can be one of: -40, -30, -20, -16, -12, -8, -4, 0, 2, 3, 4, 5, 6, 7, 8 (dBm)

Table 4: C209 AT commands
For +TXPWR to take effect the software must be reset, by pressing the reset button or power cycling
the module. The configuration is persistently stored in flash.

All commands are echoed and responded with either rnOKrn or rnERRORrn, and should be terminated with r.

The UART interface is available for 10 seconds after reset with the settings 115200 bps, with no
flow control.

5.2.2 Enabling/disabling advertising
Press and hold the C209 button for ~3 seconds to enable/disable advertising. If the tag is advertising, press and hold the button to stop it advertising. The onboard RGB LED blinks blue when advertising is enabled. The blinking interval correlates to the advertising interval.

5.3 Restore Eddystone Instance ID
All u-blox modules are delivered with a u-blox MAC address, which is written into the UICR register.
If the MAC address is accidentally erased, for example during a reflash of the software, this information is lost. If this happens, the Eddystone Instance ID transmitted in the C209 advertising beacon will not match the MAC address of the module. To correct this:
1. Scan the QR code on the module label. The information in the code includes a code that includes the MAC address (shown here in bold): H85(CCF9578E0D89)0400.
2. While having a debugger connected to the SWD interface of the board enter these commands to reinstate the MAC address CCF9578E0D89 into the UICR of the module:
nrfjprog –memwr 0x10001080 –val 0x8E57F9CC nrfjprog –memwr 0x10001084 –val 0xFFFF890D
Another example for which the MAC address given in the scan code is 0123456789AB:
nrfjprog –memwr 0x10001080 –val 0x67452301 nrfjprog –memwr 0x10001084 –val 0xFFFFAB89
3. After writing the MAC address, reset the module. The module now transmits the correct Eddystone Instance ID for the C209 tag.

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6 Running system
Once the system is setup, each anchor reports, over the serial port connection, angle calculation events (+UUDF) when it detects a beacon:
+UUDF:CCF9578E0D8A,-42,20,0,-43,37,”CCF9578E0D89″,””,15869 +UUDF:CCF9578E0D8B,-41,10,4,-42,38,”CCF9578E0D89″,””,15892 +UUDF:CCF9578E0D8A,-42,-10,2,-43,39,”CCF9578E0D89″,””,15921 … The data reported in this event can be used to estimate a position of the tracked beacon.
The parameters of the +UUDF event are (in order from left to right):
· Eddystone instance ID · RSSI of 1st polarization · Azimuth angle · Elevation angle · Reserved parameter · The advertising channel where the advertisement was found. The advertisement channel is one of
the normal Bluetooth low energy advertisement channels (37, 38 or 39) · Anchor ID as set by AT+UDFCFG tag 4. For more details, see Appendix A.3. · User defined strings as set by AT+UDFCFG tag 2. For more details. See also Configure direction
finding +UDFCFG. · Timestamp
For a detailed description of the +UUDF event parameters, see also Angle calculation event +UUDF.
As in the angle calculation events shown above, the beacon is moving from one side of the anchor to the other as the azimuth angle, given as the third parameter in the command (shown in bold), moves from a positive value (20) to a negative value (-10). The geometric relationships of the azimuth values and the orientation of the angles in relation to the C211 board are represented in the scientific diagram shown in Figure 16.

Figure 16: C211 azimuth angles.
The optimal distance between anchor nodes and tags is approximately 215 m.

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The angle events can also be visualized in the s-center [7] support application using the “IoT->Angle of Arrival” tab, as shown in Figure 17.

Figure 17: s-center with Angle of Arrival tab

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Appendix

A Anchor node AT commands

A.1 Direction finding enable +UDFENABLE

+UDFENABLE Modules Attributes

NINA-B41X-40B Syntax Full

Settings saved No

Can be aborted No

Response time –

A.1.1 Description
AT Command AT+UDFENABLE=

Description Start or stop angle calculations during runtime

A.1.2 Syntax
Response OK ERROR

Description Successful write response Error Response

A.1.3 Defined values

Parameter Enabled

Type Integer

Description 0: Disabled 1: Enabled

A.2 Direction finding filter +UDFFILT

+UDFFILT Modules Attributes

NINA-B41X-40B Syntax Full

Settings saved Yes

Can be aborted No

Response time –

A.2.1 Description

Configure a filter to decide which tags to track. This command is used to configure the filter to either track all devices with a specific namespace, or individual tags with a certain namespace and instance id. Currently, only filter types 1,2 (EDDYSTONE) are supported.

AT command
AT+UDFFILT=,[, ,,…]]] AT+UDFFILT=

Description Set the tag filter for tracked tags
Read the current filter for the specified

A.2.2 Syntax

Response +UDFFILT:,,.. OK OK
Error

Description Read response
Successful write response Error response

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A.2.3 Defined values
Parameter filter_type action
option_val

Type Enumerator Enumerator

Description Filter type, see description in table below 1: clear filter 2: append to filter Filter values, see description in table below

Filter type Description

1

Eddystone namespace

2

Eddystone instance id

Option values

Option Type

option_val1: Eddystone namespace id. String (10 HEX chars) Only one namespace can be set.

option_val2: Eddystone instance id. Up to 100 instance ids can be set.

String (6 HEX chars)

Optional Yes
Yes

A.2.4 Notes
This setting takes effect immediately. Use the command &W and +CPWROFF to store the configuration to startup database. Maximum filter length is 100.
All hexadecimal data needs to be quoted, e.g., AT+UDFFILT=2,2,”0011223344FF”.

A.3 Configure direction finding +UDFCFG

+UDFCFG Modules Attributes

NINA-B41X-40B Syntax Full

Settings Saved Yes

Can be aborted No

Response Time –

A.3.1 Description

This command is used to configure the direction-finding algorithm and the anchor output.

AT Command AT+UDFCFG=, AT+UDFCFG? AT+UDFCFG=

Description Write config Read all config options Read individual configuration

A.3.2 Syntax
Response +UDFCFG:, … OK OK ERROR

Description Read response
Successful write response Error Response

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A.3.3 Defined values

Param. tag 1

Min value/ length
0

Max value/ length 10000

Default value 1

Type

Description

Integer

Minimum interval between +UUDF events for each tag in milliseconds.

2

0

30

“”

String

+UUDF events may arrive at a smaller interval if multiple tags are tracked. This setting is used if the host cannot handle the rate of +UUDF events generated or when debugging to get less outputs. In a real scenario, it is better to just throw away the +UUDF events on host if they cannot be processed.
User defined string that can be set to any value.

3

0

1

Integer

For example, it can be useful to set a GPS position (longitude/latitude) of the anchor for use in a positioning engine. Leave blank if not needed.
Angle calculations enabled at startup.

4

0

30

MAC address String

This setting makes the anchor output +UUDF events at startup without the need to call +UDFENABLE.
Anchor ID.

5

0

1

Integer

This sets the Anchor ID field in the +UUDF event. It can be useful when the host just blindly forwards the +UUDF to a server.
Configure if the anchor is to calculate both azimuth and elevation angles.

0: Only the azimuth angle is calculated and output in +UUDF event.
1: Both azimuth and elevation calculated and output in +UUDF event.

6

0

1

0

Integer

This is useful if only azimuth angle is used as the disabling elevation angle speeds up the calculation time to make the anchor more efficient.
Antenna board used:

0: C211 1: CoreHW Core Patch antenna 2: ANT-B10

7 8

0

1

0

1

Integer Integer

Valid from u-connectLocate version 1.2. For the ANT-B10 board the default is
configured to 2.
Use CoreHW output format instead of +UUDF ublox format. Apply median buffering of output angle. It is advisable to keep this enabled.

For the direction-finding configuration to take effect, use the commands &W and +CPWROFF to store the configuration to the startup database.

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A.4 Angle calculation event +UUDF

+UUDF Modules Attributes

NINA-B41X-40B Syntax Full

Settings saved No

Can be aborted No

Response time –

A.4.1 Description
Unsolicited response code for an angle calculation event.

A.4.2 Syntax

Response
+UUDF:,,,,

,,, ,

Description Angle calculation event

A.4.3 Defined values

Parameter ed_instance_id rssi_pol1 angle_azimuth angle_elevation channel anchor_id user_defined_str timestamp_ms

Type Byte_Array Integer Integer Integer Integer Integer String String Integer

Description 6 byte Eddystone instance id RSSI of polarization 1 Azimuth angle in range -90 to 90 °C Elevation angle in range -90 to 90 °C Reserved for future use Channel from which the packet angle was calculated The value set by +UDFCFG param_tag 4 The value set by +UDFCFG param_tag 2 Time since boot in milliseconds

Note that the RSSI values reported in the angle calculation events only give a very rough indication
of distance between anchor and tag. As RSSI values are prone to many error sources like
reflections of radio signals, these values should not be used to estimate position.

A.5 RS232 setting +UMRS

+UUDF Modules Attributes

NINA-B41X-40B Syntax Full

Settings saved Yes

Can be aborted No

Response time –

A.5.1 Description
Read and set RS232 settings.

A.5.2 Syntax

AT Command AT+UMRS? AT+UMRS=[,]

Description Reads current RS232 settings from the module. Applies new RS232 settings.

A.5.3 Defined values

Parameter baud_rate

Type Integer

flow_control

Integer

Description
Factory default value 115200 Valid baud rates: 19200, 28800, 31250, 38400, 56000, 57600, 76800, 115200, 230400, 250000, 460800, 921600, 100000
0: CTS/RTS not used.

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Parameter

Type

Description 1 (factory default): CTS/RTS used for flow control

A.5.4 Notes
This command requires a store (AT&W) and restart (AT+CPWROFF) to take effect.

A.6 Other supported AT commands
· Attention AT · Manufacturer identification AT+GMI · Model identification AT+GMM · Software identification ATI9 · Software version identification AT+GMR · Local address AT+UMLA · Store current configuration AT&W · Module switch off AT+CPWROFF · Set to factory defined configuration AT+UFACTORY · Enter FW update mode AT+UFWUPD (Only mode 0 and baud config supported.) · Startup event +STARTUP
For detailed information about the AT commands listed above, line termination character and so on, see also the u-connectXpress AT commands manual [5].

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B Glossary

Abbreviation AoA AoD CTE RSSI UICR

Definition Angle of Arrival Angle of Departure Constant Tone Extension Received Signal Strength Indication User Information Configuration Register

Table 5: Explanation of the abbreviations and terms used

C Limitations
The u-connectLocate software (1.2 and higher) supports tracking of up to 20 individual tags. Tags that do not send any data for more than five seconds are considered as idle and are removed from the list of tracked tags. Newly identified tags are automatically added to the list of tracked tags.

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D C209 schematics

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Related documentation
[1] Bluetooth Direction Finding: A Technical Overview https://www.bluetooth.com/bluetooth-resources/bluetooth-direction-finding/
[2] Bluetooth indoor positioning application note, UBX-21006395 [3] NINA-B41 product page, https://www.u-blox.com/en/product/nina-b41-series-u-connect [4] NINA-B40 product page, https://www.u-blox.com/en/product/nina-b40-series-open- cpu [5] u-connectXpress AT commands manual, UBX-14044127 [6] NINA-B4 system integration manual, UBX-19052230 [7] s-center, https://www.u-blox.com/en/product/s-center [8] u-blox webinars, https://www.u-blox.com/en/webinar [9] newtmgr download: https://mynewt.apache.org/latest/newtmgr/install/install_windows.html [10] Newt Manager Guide: https://mynewt.apache.org/latest/newtmgr/index.html [11] https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrfutil%2FUG%2Fnrfutil%2Fnrfut
il_intro.html [12] https://github.com/NordicSemiconductor/pc-nrfutil/releases [13] https://github.com/u-blox/c209-aoa-tag [14] NINA-B40 series data sheet, UBX-19049405 [15] NINA-B41 series data sheet, UBX-20035327 [16] EVK-ODIN-W2 user guide, UBX-16007132 [17] u-connectXpress software user guide, UBX-16024251 [18] s-center user guide, UBX-16012261 [19] https://www.u-blox.com/en/product/u-connectlocate [20] FTDI website https://ftdichip.com/drivers/
For product change notifications and regular updates of u-blox documentation, register on our
website, www.u-blox.com.