AIROC™ BTSTACK: Bluetooth® Alert Client(ANC) for Linux host

This code example demonstrates Bluetooth® Alert Client using AIROC™ Wi-Fi & Bluetooth® combo chip.

Requirements

• Programming language: C
• Embedded Linux platforms (Arm® Cortex®-A Class processors) for host communications. Supported Embedded Linux host platforms:
  1. RPI CM4-lite IFX custom HW board from Infineon
  2. IMX8 nano uCOM board from Embedded Artists
• AIROC™ BTSTACK library and Linux porting layer source code
• AIROC™ Wi-Fi & Bluetooth® combo chip Bluetooth® Firmware file (.hcd).
• Linux Host PC with Ubuntu 20.04

Supported toolchains (make variable 'TOOLCHAIN')

• GNU Arm® GCC AArch64 v9.3.0 (GCC_ARM)

Supported AIROC™ Wi-Fi & Bluetooth® combo chip

• AIROC™ CYW5557x Wi-Fi & Bluetooth® combo chip

Hardware setup

Set up the hardware required for this code example as follows:

Figure 1. Hardware setup block diagram

Software setup

Set up a cross compiler according to the target platform requirement along with CMake on the Linux host PC based on Ubuntu 20.04.

Note: These steps are for Arm® 64-based target platform. Review these steps before adding support for any other target.

1. Open a terminal on the Linux host PC.

2. Use the following command to install the cross compiler, build tools, and dependencies:

   sudo apt-get install git cmake gcc-aarch64-linux-gnu build-essential -y
   

Using the code example

This section describes the steps to be executed on the Linux host PC for compiling the code example.

1. Create a directory under $HOME on the Linux host PC and switch to the created directory. Use the following commands for reference:

   mkdir $HOME/Linux_CE
   cd $HOME/Linux_CE

2. Fetch the code example source code using the following command:

   git clone https://github.com/Infineon/linux-example-btstack-alert-client

3. Clone the code example dependencies (BTSTACK library and Linux porting layer source code) using the following commands:

   git clone https://github.com/Infineon/btstack --branch release-v3.6.0
   git clone https://github.com/Infineon/bluetooth-linux.git --branch release-v1.0.0

   Creates three different directories after cloning the code example and its dependencies with the directory structure as follows:

   Figure 3. Code example directory structure

   

4. Clone the Bluetooth® firmware using following command.

   git clone https://github.com/Infineon/combo-bluetooth-firmware.git

   User can choose appropriate Bluetooth® firmware for particular AIROC™ Wi-Fi & Bluetooth® combo chip from cloned "combo-bluetooth-firmware" directory.

5. Create the build folder under the code example source folder and build the code example using the following commands:

   cd $HOME/Linux_CE/linux-example-btstack-alert-client
   mkdir build && cd build
   cmake -DCMAKE_C_COMPILER:PATH=<GCC_CROSS_COMPILER> ../ && make
   

   Where,

   • GCC_CROSS_COMPILER is the target cross compiler for GCC (generally /usr/bin/aarch64-linux-gnu-gcc for ARM64-based targets)

   The code example executable is generated under the build folder with the same name of code example.

   For example, in this project, the "linux-example-btstack-alert-client" executable is generated at /home/$USER/Linux_CE/linux-example-btstack-alert-client/build.

Operation

Using two hardware platforms (Linux host platform and AIROC™ Wi-Fi & Bluetooth® combo chip)

Devices used:

• Device Under Test (DUT): Linux host platform with AIROC™ Wi-Fi & Bluetooth® combo chip (target platform). Implements: "Alert Notification Client", GATT Client.

• Testing Device: Linux host platform with AIROC™ Wi-Fi & Bluetooth® combo chip (target platform). Used as: "Alert Notification Server", GATT Server. User can get ANS application from here

1. Copy the code example executable and AIROC™ BTSTACK library from the Linux host PC to the target platform using SCP. For example, use the following commands:

   cd $HOME/Linux_CE/linux-example-btstack-alert-client/build
   scp linux-example-btstack-alert-client <TARGET_USER>@<TARGET_IP>:<TARGET_PATH>/.
   cd $HOME/Linux_CE/btstack/stack/COMPONENT_WICED_DUALMODE/COMPONENT_ARMv8_LINUX/COMPONENT_GCC
   scp libbtstack.so <TARGET_USER>@<TARGET_IP>:<TARGET_PATH>/.
   scp <FW_FILE.hcd> <TARGET1_USER>@<TARGET1_IP>:<TARGET1_PATH>/.
   

   Where,

   • TARGET_USER is the user name of the target platform
   • TARGET_IP is the IP address of the target platform
   • TARGET_PATH is the path of target platform
   • FW_FILE.hcd file is Bluetooth® Firmware file cloned in step-4 of Using the code example section.

2. Take SSH console of target platform.

   ssh <TARGET_DEVICE_USER_NAME>@<TARGET_DEVICE_IP_ADDRESS>

3. Add the udev rule in the target host board for HCI UART and GPIO to bypass root access. Use the following steps to create and set up a udev rule.

   Note: If you have root access, the following udev rules are not required; you can execute the code example with sudo permissions or by switching to the root user.

   1. Create a new .rules (for example, combo-chip-uart-port.rules) file under /etc/udev/rules.d/ directory for HCI UART. Use the following commands:

      IMX8Nano:

      echo "KERNEL==\"ttymxc0\"d,SYMLINK+=\"combo_chip_uart\",MODE=\"0666\"" | sudo tee /etc/udev/rules.d/combo-chip-uart-port.rules

      RPICM4:

      echo "KERNEL==\"ttyAMA0\",SYMLINK+=\"combo_chip_uart\",MODE=\"0666\"" | sudo tee /etc/udev/rules.d/combo-chip-uart-port.rules

   2. Create new .rules (for example, combo-chip-gpio-port.rules) for BT_REG_ON GPIO under /etc/udev/rules.d/. Use the following commands:

      IMX8Nano & RPICM4:

      1. Create a rule file using the following command.

         sudo vim /etc/udev/rules.d/combo-chip-gpio-port.rules.rules

      2. Add the following rules in created files:

         SUBSYSTEM=="gpio*", PROGRAM="/bin/sh -c 'chown -R $user:$group /sys/class/gpio/export /sys/class/gpio/unexport;'"
         SUBSYSTEM=="gpio*", PROGRAM="/bin/sh -c 'chown -R $user:$group /sys%p/direction /sys%p/value; chmod 660 /sys%p/direction /sys%p/value;'"

   3. Reboot the target device:

      sudo reboot

      Where,

      • ttymxc0 and ttyAMA0 are HCI UART ports for IMX8Nano and RPICM4 respectively
      • combo_chip_uart is a friendly name for the HCI UART port
      • 0666 is the permission mask to bypass the root access for HCI UART

4. Execute the application by setting the paths of the AIROC™ BTSTACK library using the following command on the target platform:

   cd <TARGET_PATH>
   chmod +x <APP_NAME>
   LD_LIBRARY_PATH=$LD_LIBRARY_PATH:<BTSTACK_LIB_PATH>
   ./<APP_NAME> -c <COM_PORT> -b 3000000 -f 921600 -r <GPIOCHIPx> <REGONPIN> -n -p <FW_FILE_NAME>.hcd -d 112233221133
   

   Where,

   • TARGET_PATH is the path of the target platform where the code example application copied
   • BTSTACK_LIB_PATH is path of the AIROC™ BTSTACK library. Skip this if the AIROC™ BTSTACK library and code example application executable are in the same folder
   • /dev/ttymxc0 is the COM port for IMX8-NANO
   • /dev/ttyAMA0 is the COM port for RPI CM4
   • 3000000 is HCI baud rate
   • 112233221133 is a device BD address
   • -r <GPIOCHIPx> <REGONPIN> -n is setting the GPIO control to enable autobaud for Hatchet2
     • -r gpiochip5 0 -n For IMX8-NANo
     • -r gpiochip0 3 -n For RPI CM4
   • 921600 is FW download baudrate
   • .hcd is FW file to download (Make sure to validate this FW file file path)

   Note 1: Currently, random BD addresses are used for testing. Note 2: This code example supports maximum of 1 paired device. If the user is connecting to a new device, nvramxxx.bin should be deleted on the DUT.

5. To test this Code example "Alert Notifications Client" (ANC) with the testing device runs "Alert Notification Server" (ANS) code example , do the following:

   1. Start the 'Alert Server" application on the testing device.

   2. Start the "Alert Client" application on the DUT as mentioned in Step 4 of the Operation section.

   3. Choose Option #1 to start advertising, the ANC code example will start Bluetooth® LE advertisements and waits for scan and connect from a remote device that supports ANS.

      

   4. Once the advertising starts at ANC, On the ANS testing device user can choose 'Scan and Connect' option to connect to ANC automatically.

   5. If an ANS testing device is not connected with in 90 seconds, the advertising is stopped automatically. The user has to choose the option again to restart the advertising.

   NOTE: If the remote device bonds with the ANC device, then the Link keys will be saved for further retrieval. If user is connecting a fresh device that is not previously paired, then delete the nvramxxx.bin from the current directory.

   6. Once connected, the Alert Notification Service is seen on the ANC.

   7. On ANC, user can choose Option #2 to read the Alert Notification for New Alerts and/or Option #3 for Unread alerts by sending a READ request to the ANS.

   8. Also, with Option #4 the categories of the Alert can be written through the Control Point on ANC to set any particular categories for receiving the Notifications for a particular category.

   

   9. Option #5 and #6 can be used to Enable the Notifications of New and Unread Alerts in general.

   10. On testing ANS, The user can use the 'Generate Alert' option to generate alerts and 'Clear alert' option to clear the alerts. This option will send notification of new/ unread alert to the ANC.

   11. The application allows the user to enable and disable the available alert categories support at client side.

   12. After connection to the ANC device, the ANS testing device sends new alerts and unread alerts to the client based on ANC configuration. New alerts and unread alerts get generated as follows:

   • User generates the alert when an ANS device has a connection with an ANC device.
   • When the user generates an Alert using the Menu on the testing ANS, the ANC device receives the new alert and unread alert.
   13. User can choose option #6 the ANS testing device to disconnect the Bluetooth® connection.

Debugging

You can debug the example using a generic Linux debugging mechanism such as the following:

1. Debugging by logging: Add prints in the application and check them during the execution.

2. Debugging using GDB: See GDB man page for more details.

Design and implementation

Roles implemented:

• CE code example (implementation under test): Alert Notification Client, GATT Client, and GAP Central role

• Testing device running Alert Notification Server Code Example: Alert Notification Server, GATT Server, and GAP Peripheral role

Alert Notification Client (ANC) working:

The Alert Notification Client (the Bluetooth® Low Energy Peripheral device) is a Bluetooth® Low Energy GATT Client.

The ANC advertises the Device Name and GAP services and expects a Connect request from remote ANS device that exposes Alert notification Service with various categories. When ANC device does a service discovery using the "GATT Discover All Primary Services" procedure, these services are available to the ANC to configure and use. The Bluetooth® Low Energy Service Characteristic discovery is done by the "Discover All Characteristics of a Service" procedure. When the user wants to configure any alert category on the ANS, the ANC writes to the Alert Notification Control Point in the Alert Level characteristic of the ANS using the Control Commands. When the user triggers an Alert (New/ Unread) on ANS device, the ANC receives the alert and required info as per the configuration.

This code example does the following:

1. Parses the command-line arguments and initializes the AIROC™ BTSTACK library for the CYW5557x device

2. On starting the ANC Code example, the application registers alert notification client with the GATT protocol.

3. Provides options as follows:

   ---

     Alert Notification Client Menu 
   

   ---

   0. Exit
   1. Start Advertising
   2. Read Supported New Alert Categories
   3. Read Supported Unread Alert Categories
   4. Control Required Alerts
   5. Enable New Alerts Notification
   6. Enable Unread Alert Status Notification
   7. Disable New Alerts Notification
   8. Disable Unread Alerts Status Notification

   ---

   Choose option (0-8):

4. Application follows the sequence as shown in the flowchart(figure4) above.

5. On choosing 0, the application exits.

Note: Run the application without any arguments to get details of command-line arguments.

Source files

Files	Description of files
app/main.c	Implements the main function which takes the user command-line inputs.
app_bt_utils/app_bt_utils.c	Contains utility functions like functions to print error codes, status, etc in a user-understandable format.
app_bt_utils/app_bt_utils.h	Header file corresponding to app_bt_utils.c
app/bt_app_ans.c	Functions for all the Alert Notification Server functionalities.
include/bt_app_anc.h	Header file corresponding to bt_app_anc.c.
app_bt_config/anc_bt_settings.c	Contains Bluetooth® stack configuration parameters.
app_bt_config/anc_gap.c	Contains Bluetooth® GAP parameters.
app_bt_config/anc_gatt_db.c	Contains Bluetooth® GATT database.

Resources and settings

Table 1. Application resources

Resource	Alias/object	Purpose
UART	HCI	UART is used for HCI communication with host system

Related resources

Resources	Links
Device documentation	CYW5557x
AIROC™ BTSTACK library	AIROC™ BTSTACK library
Linux porting layer source code	Linux porting layer source code

Other resources

Infineon provides a wealth of data at www.infineon.com to help you select the right device, and quickly and effectively integrate it into your design.

Document history

Document title: CE237177 - AIROC™ BTSTACK: Bluetooth® Alert Client(ANC) for Linux host

Version	Description of change
1.0.0	New code example

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