The Project CHIP K32W061 Contact Sensor Example uses buttons to test changing the lock and device states and LEDs to show the state of these changes. You can use this example as a reference for creating your own application.
The example is based on Project CHIP and the NXP K32W SDK, and a simulated contact sensor over a low-power, 802.15.4 Thread network.
The example behaves as a Project CHIP accessory, that is a device that can be paired into an existing Project CHIP network and can be controlled by this network.
The K32W061 contact sensor example application provides a working demonstration of a connected contact sensor device, built using the Project CHIP codebase and the NXP K32W061 SDK. The example supports remote access (e.g.: using CHIP Tool from a mobile phone) and control of a simulated contact sensor over a low-power, 802.15.4 Thread network. It is capable of being paired into an existing Project CHIP network along with other Project CHIP-enabled devices.
The example targets the NXP K32W061 DK6 development kit, but is readily adaptable to other K32W-based hardware.
The CHIP device that runs the contact sensor application is controlled by the CHIP controller device over the Thread protocol. By default, the CHIP device has Thread disabled, and it should be paired over Bluetooth LE with the CHIP controller and obtain configuration from it. The actions required before establishing full communication are described below.
The example also comes with a test mode, which allows to start Thread with the default settings by pressing a button. However, this mode does not guarantee that the device will be able to communicate with the CHIP controller and other devices.
Deployment of this firmware configuration requires the K32W061 board setups using the K32W061 module board, SE051 Expansion board and Generic Expansion board as shown below:
The SE051H Secure Element extension may be used for best in class security and offloading some of the Project CHIP cryptographic operations. Depending on your hardware configuration, choose one of the options below (building with or without Secure Element). NOTE: the SE051H is a derivative of the SE051 product family (see http://www.nxp.com/SE051) including dedicated CHIP support in addition to the SE051 feature set. See the material provided separately by NXP for more details on SE051H.
In this example, to commission the device onto a Project CHIP network, it must be discoverable over Bluetooth LE. For security reasons, you must start Bluetooth LE advertising manually after powering up the device by pressing Button USERINTERFACE.
If the device is acting as a LIT ICD and it's already commissioned, then Button USERINTERFACE can be pressed for forcing the switch to Active Mode.
In this example, the commissioning procedure (called rendezvous) is done over Bluetooth LE between a CHIP device and the CHIP controller, where the controller has the commissioner role.
To start the rendezvous, the controller must get the commissioning information from the CHIP device. The data payload is encoded within a QR code, printed to the UART console and shared using an NFC tag. For security reasons, you must start NFC tag emulation manually after powering up the device by pressing Button 4.
Last part of the rendezvous procedure, the provisioning operation involves sending the Thread network credentials from the CHIP controller to the CHIP device. As a result, device is able to join the Thread network and communicate with other Thread devices in the network.
The example application provides a simple UI that depicts the state of the device and offers basic user control. This UI is implemented via the general-purpose LEDs and buttons built in to the OM15082 Expansion board attached to the DK6 board.
LED D2 shows the overall state of the device and its connectivity. Four states are depicted:
LED D3 shows the state of the simulated contact sensor. when the LED is lit, the sensor is contacted, when not lit, the sensor is non-contacted.
Button SW2 can be used to reset the device to a default state. A short Press Button SW2 initiates a factory reset. After an initial period of 3 seconds, LED2 D2 and D3 will flash in unison to signal the pending reset. After 6 seconds will cause the device to reset its persistent configuration and initiate a reboot. The reset action can be cancelled by press SW2 button at any point before the 6 second limit.
Button SW3 can be used to change the state of the simulated contact sensor. The button behaves as a toggle, swapping the state every time it is pressed.
Button SW4 can be used for initiating the OTA software update process.
The remaining two LEDs (D1/D4) and button (SW1) are unused.
Directly on the development board, Button USERINTERFACE can be used for enabling Bluetooth LE advertising for a predefined period of time. Also, pushing this button starts the NFC emulation by writing the onboarding information in the NTAG.
In case the OM15082 Expansion board is not attached to the DK6 board, the functionality of LED D2 and LED D3 is taken over by LED DS2, respectively LED DS3, which can be found on the DK6 board.
Also, by long pressing the USERINTERFACE button, the factory reset action will be initiated.
When low power is enabled, the ISP button on DK6 board is used to change contact status.
In order to build the Project CHIP example, we recommend using a Linux distribution (the demo-application was compiled on Ubuntu 20.04).
Activate the Matter environment:
user@ubuntu:~/Desktop/git/connectedhomeip$ source ./scripts/activate.sh
To bring the SDK in the environment, the user can:
download it with west tool, in which case it will be handled automatically by gn:
user@ubuntu:~/Desktop/git/connectedhomeip$ cd third_party/nxp/k32w0_sdk/repo user@ubuntu:~/Desktop/git/connectedhomeip/third_party/nxp/k32w0_sdk/repo$ west init -l manifest --mf west.yml user@ubuntu:~/Desktop/git/connectedhomeip/third_party/nxp/k32w0_sdk/repo$ west update
In case there are local modification to the already installed github NXP SDK, use the below west forall command instead of the west init command to reset the west workspace. Warning: all local changes will be lost after running this command.
user@ubuntu:~/Desktop/git/connectedhomeip$ cd third_party/nxp/k32w0_sdk/repo user@ubuntu:~/Desktop/git/connectedhomeip/third_party/nxp/k32w0_sdk/repo$ west forall -c "git reset --hard && git clean -xdf" -a
set up a custom path to the SDK, in which case k32w0_sdk_root=\"${NXP_K32W0_SDK_ROOT}\" must be added to the gn gen command:
user@ubuntu:~/Desktop/git/connectedhomeip$ export NXP_K32W0_SDK_ROOT=/custom/path/to/SDK
Start building the application:
user@ubuntu:~/Desktop/git/connectedhomeip$ cd examples/contact-sensor-app/nxp/k32w/k32w0 user@ubuntu:~/Desktop/git/connectedhomeip/examples/contact-sensor-app/nxp/k32w/k32w0$ gn gen out/debug user@ubuntu:~/Desktop/git/connectedhomeip/examples/contact-sensor-app/nxp/k32w/k32w0$ ninja -C out/debug
To build with Secure Element, follow the same steps as above but set chip_with_se05x=1 chip_enable_ota_requestor=false in the gn gen command.
Note that option chip_enable_ota_requestor=false is required for building with Secure Element due to flash constraints.
K32W041AM flavor
Exactly the same steps as above but set argument build_for_k32w041am=1 in the gn command.
Also, in case the OM15082 Expansion Board is not attached to the DK6 board, the build argument (chip_with_OM15082) inside the gn build instruction should be set to zero. The argument chip_with_OM15082 is set to zero by default.
In case that Openthread CLI is needed, chip_with_ot_cli build argument must be set to 1.
In case the board doesn't have 32KHz crystal fitted, one can use the 32KHz free running oscillator as a clock source. In this case one must set the use_fro_32k argument to 1.
K32W0x1 supports antenna diversity feature, which is a technique that maximizes the performance of an antenna system, allowing the radio signal to be switched between two antennas that have very low correlation between their received signals. Typically, this is achieved by spacing two antennas around 0.25 wavelengths apart or by using 2 orthogonal types of polarization. This is controlled by software. K32W0x1 provides an output (ADO) on one of DIO7, DIO9 or DIO19 and optionally its complement (ADE) on DIO6 that can be used to control an antenna switch. In order to use this feature, user must set use_antenna_diversity to 1.
In case signing errors are encountered when running the “sign_images.sh” script (run automatically) install the recommanded packages (python version > 3, pip3, pycrypto, pycryptodome):
user@ubuntu:~$ python3 --version Python 3.8.2 user@ubuntu:~$ pip3 --version pip 20.0.2 from /usr/lib/python3/dist-packages/pip (python 3.8) user@ubuntu:~$ pip3 list | grep -i pycrypto pycrypto 2.6.1 pycryptodome 3.9.8
The resulting output file can be found in out/debug/chip-k32w0x-contact-example.
By default, contact-sensor is compiled as SIT ICD (Short Idle Time Intermittently Connected Device) - see rules from k32w0_sdk.gni:
chip_ot_idle_interval_ms = 2000 # 2s Idle Intervals chip_ot_active_interval_ms = 500 # 500ms Active Intervals nxp_idle_mode_duration_s = 600 # 10min Idle Mode Interval nxp_active_mode_duration_ms = 10000 # 10s Active Mode Interval nxp_active_mode_threshold_ms = 1000 # 1s Active Mode Threshold nxp_icd_supported_clients_per_fabric = 2 # 2 registration slots per fabric
If LIT ICD support is needed then chip_enable_icd_lit=true must be specified as gn argument and the above parameters can be modified to comply with LIT requirements (e.g.: LIT devices must configure chip_ot_idle_interval_ms > 15000). Example LIT configuration:
chip_ot_idle_interval_ms = 15000 # 15s Idle Intervals chip_ot_active_interval_ms = 500 # 500ms Active Intervals nxp_idle_mode_duration_s = 3600 # 60min Idle Mode Interval nxp_active_mode_duration_ms = 0 # 0 Active Mode Interval nxp_active_mode_threshold_ms = 30000 # 30s Active Mode Threshold
ICD parameters that may be disabled once LIT functionality is enabled:
chip_persist_subscriptions: try to re-establish subscriptions from the server side after reboot chip_subscription_timeout_resumption: same as above but retries are using a Fibonacci backoff
The example uses template/reference board configuration files.
To overwrite the board configuration files, set override_is_DK6=false in the k32w0_sdk target from the app BUILD.gn:
k32w0_sdk("sdk") {
override_is_DK6 = false
...
}
This variable will be used by k32w0_sdk.gni to overwrite chip_with_DK6 option, thus the reference board configuration files will no longer be used.
This is an optional feature and can be used in multiple ways (please see section 5.4.2.4.5 from Matter specification). One use case is Amazon Frustration Free Setup, which leverages the C3 Characteristic (Additional commissioning-related data) to offer an easier way to set up the device. The rotating device id will be encoded in this additional data and is programmed to rotate at pre-defined moments. The algorithm uses a unique per-device identifier that must be programmed during factory provisioning.
Please use the following build args:
chip_enable_rotating_device_id=1 - to enable rotating device id.chip_enable_additional_data_advertising=1 - to enable C3 characteristic.See Guide for writing manufacturing data on NXP devices.
There are factory data generated binaries available in examples/platform/nxp/k32w/k32w0/scripts/demo_generated_factory_data folder. These are based on the DAC, PAI and PAA certificates found in scripts/tools/nxp/demo_generated_certs folder. The demo_factory_data_dut1.bin uses the DAC certificate and private key found in examples/platform/nxp/k32w/k32w0/scripts/demo_generated_factory_data/dac/dut1 folder. The demo_factory_data_dut2.bin uses the DAC certificate and private key found in examples/platform/nxp/k32w/k32w0/scripts/demo_generated_factory_data/dac/dut2 folder. These two factory data binaries can be used for testing topologies with 2 DUTS. They contain the corresponding DACs/PAIs generated using generate_nxp_chip_factory_bin.py script. The discriminator is 14014 and the passcode is 1000. These demo certificates are working with the CDs installed in CHIPProjectConfig.h.
Regarding factory data provider, there are two options:
FactoryDataProviderImpl by setting chip_with_factory_data=1 in the gn build command.chip_with_factory_data=1 by setting use_custom_factory_provider=1 in the gn build command.Program the firmware using the official OpenThread Flash Instructions.
All you have to do is to replace the Openthread binaries from the above documentation with out/debug/chip-k32w0x-contact-example.bin if DK6Programmer is used or with out/debug/chip-k32w0x-contact-example if MCUXpresso is used.
The tokenizer is a pigweed module that allows hashing the strings. This greatly reduces the flash needed for logs. The module can be enabled by building with the gn argument chip_pw_tokenizer_logging=true. The detokenizer script is needed for parsing the hashed scripts.
The python3 script detokenizer.py is a script that decodes the tokenized logs either from a file or from a serial port. It is located in the following path examples/platform/nxp/k32w/k32w0/scripts/detokenizer.py.
The script can be used in the following ways:
usage: detokenizer.py serial [-h] -i INPUT -d DATABASE [-o OUTPUT] usage: detokenizer.py file [-h] -i INPUT -d DATABASE -o OUTPUT
The first parameter is either serial or file and it selects between decoding from a file or from a serial port.
The second parameter is -i INPUT and it must se set to the path of the file or the serial to decode from.
The third parameter is -d DATABASE and represents the path to the token database to be used for decoding. The default path is out/debug/chip-k32w0x-contact-example-database.bin after a successful build.
The forth parameter is -o OUTPUT and it represents the path to the output file where the decoded logs will be stored. This parameter is required for file usage and optional for serial usage. If not provided when used with serial port, it will show the decoded log only at the stdout and not save it to file.
The token database is created automatically after building the binary if the argument chip_pw_tokenizer_logging=true was used.
The detokenizer script must be run inside the example's folder after a successful run of the scripts/activate.sh script. The pw_tokenizer module used by the script is loaded by the environment. An example of running the detokenizer script to see logs of a contact-sensor app:
python3 ../../../../../examples/platform/nxp/k32w/k32w0/scripts/detokenizer.py serial -i /dev/ttyACM0 -d out/debug/chip-k32w0x-contact-example-database.bin -o device.txt
The building process will not update the token database if it already exists. In case that new strings are added and the database already exists in the output folder, it must be deleted so that it will be recreated at the next build.
Not all tokens will be decoded. This is due to a gcc/pw_tokenizer issue. The pw_tokenizer creates special elf sections using attributes where the tokens and strings will be stored. This sections will be used by the database creation script. For template C++ functions, gcc ignores these attributes and places all the strings by default in the .rodata section. As a result the database creation script won't find them in the special-created sections.
If run, closed and rerun with the serial option on the same serial port, the detokenization script will get stuck and not show any logs. The solution is to unplug and plug the board and then rerun the script.
By default, the application builds with NXP Ultrafast P256 ECC Library. To build with this library, use the following arguments:
To stop using Ultrafast P256 ECC Library, simply build with chip_crypto="mbedtls" or with Tinycrypt.
In order to use the Tinycrypt ECC library, use the following build arguments:
The internal flash needs to be prepared for the OTA process. First 16K of the internal flash needs to be populated with a Secondary Stage Bootloader (SSBL) related data while the last 8.5K of flash space is holding image directory related data (PSECT). The space between these two zones will be filled by the application.
The SDK already provides an SSBL binary compiled with external flash support: boards/k32w061dk6/wireless_examples/framework/ssbl/binary/ssbl_ext_flash_pdm_support.bin, but it does not offer multi-image OTA support.
Alternatively, the SSBL can ge generated from one of the SDK demo examples. The SSBL demo application can be imported from the Quickstart panel: Import SDK example(s) -> select wireless -> framework -> ssbl application.
To support multi-image OTA feature, the SSBL project must be compiled using the following defines:
PDM_EXT_FLASH=1 - support PDM in external flash.gOTAUseCustomOtaEntry=1 - support custom OTA entry for multi-image.gOTACustomOtaEntryMemory=OTACustomStorage_ExtFlash - K32W0 uses OTACustomStorage_ExtFlash (1) by default.SPIFI_DUAL_MODE_SUPPORT=1 - only for configurations that use dual SPIFI flash (e.g. K32W041AM variant).Optionally, add the following defines:
SPIFI_OPTIM_SIZE=1 - to optimize SSBL size.EXTERNAL_FLASH_DATA_OTA=1 - to support external read only data.
When secure boot is not used, a simple hash can be appended at the end of the image for integrity check. Applications should be built with chip_simple_hash_verification=1.
To support simple hash verification feature, the SSBL project must be compiled with:
gSimpleHashVerification=1and update the post-build command to use simple hash verification instead of the default options. Go to Project -> Properties -> C/C++ Build -> Settings -> Build steps and press Edit under Post-build steps subsection. The command should look similar to:
Once compiled, the required SSBL file is called k32w061dk6_ssbl.bin.
Before writing the SSBL, it it recommanded to fully erase the internal flash:
DK6Programmer.exe -V 5 -P 1000000 -s <COM_PORT> -e Flash
k32w061dk6_ssbl.bin must be written at address 0 in the internal flash:
DK6Programmer.exe -V2 -s <COM_PORT> -P 1000000 -Y -p FLASH@0x00="k32w061dk6_ssbl.bin"
This is the list of all supported partitions:
0000000010000000 : SSBL partition
00000000 -----------> Start Address
1000 ---------------> 0x0010 Number of 512-bytes pages
00 -----------------> 0x00 Bootable flag
00 -----------------> 0x00 Image type (0x00 = SSBL)
004000000f020101: Application partition
00400000 -----------> 0x00004000 Start Address
0f02 ---------------> 0x020f Number of 512-bytes pages
01 -----------------> 0x01 Bootable flag
01 -----------------> 0x01 Image type (0x01 = Application)
00000010800000fe: Ext Flash text partition
00000010 -----------> 0x10000000 Start Address (external flash)
8000 ---------------> 0x0080 Number of 512-bytes pages
00 -----------------> 0x00 Bootable flag
fe -----------------> 0xFE Image type (0xFE = Ext Flash text)
00000110300200fc : OTA Image partition
00000110 -----------> 0x10010000 Start Address
3002----------------> 0x0230 Number of 512-bytes pages
00 -----------------> 0x00 Bootable flag
fc -----------------> 0xFC Image type (0xFC = OTA partition)
00000510100000fd: NVM partition
00000510 -----------> 0x10050000 Start Address
1000 ---------------> 0x0010 Number of 512-bytes pages
00 -----------------> 0x00 Bootable flag
fd -----------------> 0xFD Image type (0xFD = NVM partition)
First, image directory 0 (SSBL partition) must be written:
DK6Programmer.exe -V5 -s <COM port> -P 1000000 -w image_dir_0=0000000010000000
Here is the interpretation of the fields:
00000000 -> start address 0x00000000 1000 -> size = 0x0010 pages of 512-bytes (= 8kB) 00 -> not bootable (only used by the SSBL to support SSBL update) 00 -> SSBL Image Type
Second, image directory 1 (application partition) must be written:
DK6Programmer.exe -V5 -s <COM port> -P 1000000 -w image_dir_1=00400000C9040101
Here is the interpretation of the fields:
00400000 -> start address 0x00004000 C904 -> 0x4C9 pages of 512-bytes (= 612.5kB) 01 -> bootable flag 01 -> image type for the application
Please note the user can write additional partitions by writing image_dir_2/3/4 with the wanted configuration.
DK6Programmer can be used for flashing the application:
DK6Programmer.exe -V2 -s <COM_PORT> -P 1000000 -Y -p FLASH@0x4000="chip-k32w0x-contact-example.bin"
If debugging is needed, MCUXpresso can be used then for flashing the application. Please make sure that the application is written at address 0x4000:
The OTA topology used for OTA testing is illustrated in the figure below. Topology is similar with the one used for Matter Test Events.
The concept for OTA is the next one:
Computer #1 can be any system running an Ubuntu distribution. We recommand using TE 7.5 instructions from here, where RPi 4 are proposed. Also, TE 7.5 instructions document point to the OS/Docker images that should be used on the RPis. For compatibility reasons, we recommand compiling chip-tool and OTA Provider applications with the same commit id that was used for compiling the Lighting Application. Also, please note that there is a single controller (chip-tool) running on Computer #1 which is used for commissioning both the device and the OTA Provider Application. If needed, these instructions could be used for connecting the RPis to WiFi.
Build the Linux OTA provider application:
user@computer1:~/connectedhomeip$ : ./scripts/examples/gn_build_example.sh examples/ota-provider-app/linux out/ota-provider-app chip_config_network_layer_ble=false
Build Linux chip-tool:
user@computer1:~/connectedhomeip$ : ./scripts/examples/gn_build_example.sh examples/chip-tool out/chip-tool-app
Build OTA image:
In order to build an OTA image, use NXP wrapper over the standard tool src/app/ota_image_tool.py:
scripts/tools/nxp/ota/ota_image_tool.py.The tool can be used to generate an OTA image with the following format:
| OTA image header | TLV1 | TLV2 | ... | TLVn |
where each TLV is in the form |tag|length|value|.
Note that “standard” TLV format is used. Matter TLV format is only used for factory data TLV value.
A user can select which default processors to enable:
chip_enable_ota_firmware_processor=1 to enable default firmware (app/SSBL) update processor (enabled by default).chip_enable_ota_factory_data_processor=1 to enable default factory data update processor (disabled by default).The address for storing the custom OTA entry can also be specified:
ota_custom_entry_address="0x000C1000" is the default value, where 0x000C1000 is the end address of the PDM area. PDM area ends at 0x00100000 (top of external flash) and has a size of 63 * 4096 bytes. The user should be aware of the external flash configuration and use an address that does not overlap with anything else.Please see more in the OTA image tool guide.
Here is an example that generates an OTA image with application update TLV:
./scripts/tools/nxp/ota/ota_image_tool.py create -v 0xDEAD -p 0xBEEF -vn 42021 -vs "1.0" -da sha256 --app-input-file chip-k32w0x-contact-example.bin chip-k32w0x-contact-example.ota
A note regarding OTA image header version (-vn option). An application binary has its own software version, given by CHIP_DEVICE_CONFIG_DEVICE_SOFTWARE_VERSION (42020 by default), which can be overwritten. For having a correct OTA process, the OTA header version should be the same as the binary embedded software version. A user can set a custom software version in the gn build args by setting chip_software_version to the wanted version.
Start the OTA Provider Application:
user@computer1:~/connectedhomeip$ : rm -rf /tmp/chip_* user@computer1:~/connectedhomeip$ : ./out/ota-provider-app/chip-ota-provider-app -f chip-k32w0x-contact-example.ota
Provision the OTA provider application and assign node id 1. Also, grant ACL entries to allow OTA requestors:
user@computer1:~/connectedhomeip$ : rm -rf /tmp/chip_*
user@computer1:~/connectedhomeip$ : ./out/chip-tool-app/chip-tool pairing onnetwork 1 20202021
user@computer1:~/connectedhomeip$ : ./out/chip-tool-app/chip-tool accesscontrol write acl '[{"fabricIndex": 1, "privilege": 5, "authMode": 2, "subjects": [112233], "targets": null}, {"fabricIndex": 1, "privilege": 3, "authMode": 2, "subjects": null, "targets": null}]' 1 0
Provision the device and assign node id 2:
user@computer1:~/connectedhomeip$ : ./out/chip-tool-app/chip-tool pairing ble-thread 2 hex:<operationalDataset> 20202021 3840
Start the OTA process:
user@computer1:~/connectedhomeip$ : ./out/chip-tool-app/chip-tool otasoftwareupdaterequestor announce-otaprovider 1 0 0 0 2 0
user@computer1:~/connectedhomeip$ : sudo docker kill $container_id
user@computer1:~/connectedhomeip$ sudo ip link set dev eth0 down user@computer1:~/connectedhomeip$ sudo ifconfig eth0 -multicast
If OTBR Docker image is used, then the “-B” parameter should point to the interface used for the backbone.
If Wi-Fi is used on a RPI4, then a 5Ghz network should be selected. Otherwise, issues related to BLE-WiFi combo may appear.
The example also offers the possibility to run in low power mode. This means that the board will go in a deep power down mode most of the time and the power consumption will be very low.
In order to build with low power support, the chip_with_low_power=1 must be provided to the build system. In this case, please note that the GN build arguments chip_with_OM15082 and chip_with_ot_cli must be set to 0 and chip_logging must be set to false to disable logging.
In order to maintain a low power consumption, the LEDs showing the state of the elock and the internal state are disabled. Console logs can be used instead. Also, please note that once the board is flashed with MCUXpresso the debugger disconnects because the board enters low power.
Power Measurement Tool can be used inside MCUXpresso for checking the power consumption pattern: Window -> Show View -> Other -> Power Measurement Tool. The configuration for this tool is the next one:
Also, please make sure that the J14 jumper is set to the ENABLED position and no expansion board is attached to the DK6. A view from this tool is illustrated below:
Please note that that the Power Measurement Tool is not very accurate and professional tools must be used if exact power consumption needs to be known.
The example also offers the possibility to remove SSBL upgrade region, for reserving more space for application level.
A new flag chip_reduce_ssbl_size is introduced. In order to remove the SSBL upgrade region, chip_reduce_ssbl_size=true must be provided to the build system
The programming method will change:
writing image directory 1 should change to
DK6Programmer.exe -V5 -s <COM port> -P 1000000 -w image_dir_1=00200000D9040101
Here is the interpretation of the fields:
00200000 -> start address 0x00002000 D904 -> 0x4D9 pages of 512-bytes (= 620.5kB) 01 -> bootable flag 01 -> image type for the application
Matter application offset address should change to
DK6Programmer.exe -V2 -s <COM_PORT> -P 1000000 -Y -p FLASH@0x2000="chip-k32w0x-contact-example.bin"