The Project CHIP K32W061 Lighting Example demonstrates how to remotely control a light bulb. The light bulb is simulated using one of the LEDs from the expansion board. It uses buttons to test turn on/turn off of the light bulb. 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 supports remote access and control of a light bulb 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 K32W lighting example application provides a working demonstration of a light bulb 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 light bulb 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 lighting 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.
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.
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 light bulb. When the LED is lit the light bulb is on; when not lit, the light bulb is off.
Button SW2 can be used to reset the device to a default state. Pressing and holding Button SW2 for 6 seconds initiates a factory reset. After an initial period of 3 seconds, LED2 D2 and D3 will flash in unison to signal the pending reset. Holding the button past 6 seconds will cause the device to reset its persistent configuration and initiate a reboot. The reset action can be cancelled by releasing the button at any point before the 6 second limit.
Button SW3 can be used to change the state of the simulated light bulb. This can be used to mimic a user manually operating a switch. The button behaves as a toggle, swapping the state every time it is pressed.
Button SW4 can be used for joining a predefined Thread network advertised by a Border Router. Default parameters for a Thread network are hard-coded and are being used if this button is pressed.
The remaining two LEDs (D1/D2) 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.
In order to build the Project CHIP example, we recommend using a Linux distribution (the demo-application was compiled on Ubuntu 20.04).
Download K32W061 SDK 2.6.3 for Project CHIP. Creating an nxp.com account is required before being able to download the SDK. Once the account is created, login and follow the steps for downloading SDK_2.6.3_K32W061DK6. The SDK Builder UI selection should be similar with the one from the image below. 
Start building the application
user@ubuntu:~/Desktop/git/connectedhomeip$ export K32W061_SDK_ROOT=/home/user/Desktop/SDK_2.6.3_K32W061DK6/
user@ubuntu:~/Desktop/git/connectedhomeip$ ./third_party/k32w_sdk/sdk_fixes/patch_k32w_sdk.sh
user@ubuntu:~/Desktop/git/connectedhomeip$ source ./scripts/activate.sh
user@ubuntu:~/Desktop/git/connectedhomeip$ cd examples/lighting-app/k32w/
user@ubuntu:~/Desktop/git/connectedhomeip/examples/lighting-app/k32w$ gn gen out/debug --args="k32w_sdk_root=\"${K32W061_SDK_ROOT}\" chip_with_OM15082=1 chip_with_ot_cli=0 is_debug=false"
user@ubuntu:~/Desktop/git/connectedhomeip/examples/lightin-app/k32w$ ninja -C out/debug
user@ubuntu:~/Desktop/git/connectedhomeip/examples/lighting-app/k32w$ $K32W061_SDK_ROOT/tools/imagetool/sign_images.sh out/debug/
Note that “patch_k32w_sdk.sh” script must be run for patching the K32W061 SDK 2.6.3.
Also, in case the OM15082 Expansion Board is not attached to the DK6 board, the build argument (chip_with_OM15082) inside the gn build instruction should be set to zero. The argument chip_with_OM15082 is set to zero by default.
In case that Openthread CLI is needed, chip_with_ot_cli build argument must be set to 1.
In case signing errors are encountered when running the “sign_images.sh” script install the recommanded packages (python version > 3, pip3, pycrypto, pycryptodome):
user@ubuntu:~$ 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-k32w061-light-example.
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-k32w061-light-example.bin if DK6Programmer is used or with out/debug/chip-k32w061-light-example if MCUXpresso is used.
The app can be deployed against any generic OpenThread Border Router. See the guide Commissioning NXP K32W using Android CHIPTool for step-by-step instructions.