This document describes how to build below Linux examples with the NXP embedded Linux Yocto SDK and then run the output executable files on the NXP i.MX 8M Mini EVK development board.
This document has been tested on:
The Yocto Project is an open source collaboration project focused on embedded Linux OS development. For more information about this project, see the Yocto Project page.
Before building the CHIP Linux Examples, the Yocto source code released by NXP needs to be downloaded, then the Yocto SDK and the EVK Linux SD card image need to be generated.
Download the Yocto source code and generate the Yocto SDK and the SD card image
The Yocto source code is maintained with a repo manifest, the tool repo is used to download the source code.
This document is tested with the i.MX Yocto 5.10.35_2.0.0 release. Run the commands below to download this release:
$ mkdir ~/bin
$ curl http://commondatastorage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
$ chmod a+x ~/bin/repo
$ export PATH=${PATH}:~/bin
$ mkdir yocto # this directory will be the top directory of the Yocto source code
$ cd yocto
$ repo init -u https://source.codeaurora.org/external/imx/imx-manifest -b imx-linux-hardknott -m imx-5.10.35-2.0.0.xml
$ repo sync
To build the Yocto Project, some packages need to be installed. The list of packages required are:
$ sudo apt-get install gawk wget git-core diffstat unzip texinfo gcc-multilib \
build-essential chrpath socat cpio python3 python3-pip python3-pexpect \
xz-utils debianutils iputils-ping python3-git python3-jinja2 libegl1-mesa libsdl1.2-dev \
pylint3 xterm
More information about the downloaded Yocto release can be found in the corresponding i.MX Yocto Project User’s Guide which can be found at NXP official website.
Change the current directory to the top directory of the Yocto source code and execute the commands below to generate the Yocto SDK:
$ MACHINE=imx8mmevk DISTRO=fsl-imx-xwayland source ./imx-setup-release.sh -b bld-xwayland $ bitbake imx-image-core -c populate_sdk
After the execution of the previous two commands, the SDK installation file can be found at tmp/deploy/sdk as a shell script. With the test environment of this document, the installation file name is:
fsl-imx-xwayland-glibc-x86_64-imx-image-core-cortexa53-crypto-imx8mmevk-toolchain-5.10-hardknott.sh
Change the current directory to the top directory of the Yocto source code and execute the commands below to generate the Yocto SD card image:
$ MACHINE=imx8mmevk DISTRO=fsl-imx-xwayland source ./imx-setup-release.sh -b bld-xwayland $ echo "IMAGE_INSTALL_append += \"libavahi-client\"" >> conf/local.conf $ bitbake imx-image-core
The Yocto image can be found at tmp/deploy/images/imx8mmevk/imx-image-core-imx8mmevk.wic.bz2. The bzip2 command should be used to unzip this file then the dd command should be used to program the output file to a microSD card by running the commands below. Then the microSD card can be used with the i.MX 8M Mini EVK.
Be cautious when executing the dd command below, make sure the of represents the microSD card device!, /dev/sdc in the command below represents a microSD card connected to the host machine with a USB adapter, however the output device name may vary.
$ bzip2 -d imx-image-core-imx8mmevk-20210812084502.rootfs.wic.bz2 $ sudo dd if=imx-image-core-imx8mmevk-20210812084502.rootfs.wic of=/dev/sdc bs=4M conv=fsync
Install the NXP Yocto SDK and set toolchain environment variables.
Execute the SDK installation file with root permission.
$ sudo tmp/deploy/sdk/fsl-imx-xwayland-glibc-x86_64-imx-image-full-cortexa53-crypto-imx8mmevk-toolchain-5.10-hardknott.sh
After the Yocto SDK is installed on the host machine, an environment setup script is also generated, and there are prompt lines telling the user to source the script each time when using the SDK in a new shell, for example:
$ . /opt/fsl-imx-xwayland/5.10-hardknott/environment-setup-cortexa53-crypto-poky-linux
Build the example application:
Assuming that the working directory has been changed the CHIP Linux Examples code, all the other steps are the same.
# If the all-clusters example is to be built
$ cd ~/connectedhomeip/examples/all-clusters-app/linux
# If the lighting example is to be built
$ cd ~/connectedhomeip/examples/lighting-app/linux
# If the thermostat example is to be built
$ cd ~/connectedhomeip/examples/thermostat/linux
$ git submodule update --init
$ source third_party/connectedhomeip/scripts/activate.sh
$ PLATFORM_CFLAGS='-DCHIP_DEVICE_CONFIG_WIFI_STATION_IF_NAME=\"mlan0\"", "-DCHIP_DEVICE_CONFIG_LINUX_DHCPC_CMD=\"udhcpc -b -i %s \"'
$ PKG_CONFIG_SYSROOT_DIR=${PKG_CONFIG_SYSROOT_DIR} \
PKG_CONFIG_LIBDIR=${PKG_CONFIG_PATH} \
gn gen out/aarch64 --args="target_os=\"linux\" target_cpu=\"arm64\" arm_arch=\"armv8-a\"
import(\"//build_overrides/build.gni\")
target_cflags=[ \"--sysroot=${SDKTARGETSYSROOT}\", \"${PLATFORM_CFLAGS}\" ]
target_ldflags = [ \"--sysroot=${SDKTARGETSYSROOT}\" ]
custom_toolchain=\"\${build_root}/toolchain/custom\"
target_cc=\"${OECORE_NATIVE_SYSROOT}/usr/bin/aarch64-poky-linux/aarch64-poky-linux-gcc\"
target_cxx=\"${OECORE_NATIVE_SYSROOT}/usr/bin/aarch64-poky-linux/aarch64-poky-linux-g++\"
target_ar=\"${OECORE_NATIVE_SYSROOT}/usr/bin/aarch64-poky-linux/aarch64-poky-linux-ar\""
$ ninja -C out/aarch64
The executable file is built under out/aarch64, it can be executed on the i.MX 8M Mini EVK which running the Yocto image previously generated as described in the sections above.
The generated executable files supports to work with below commandline argument:
--wifi
Enables Wi-Fi management feature. Required for Wi-Fi provisioning.
The Wi-Fi device on i.MX 8M Mini EVK is a module based on the NXP 88W8987 Wi-Fi/Bluetooth SoC.
--ble-device <interface id>
Use the specific Bluetooth interface for BLE advertisement and connections.
interface id: the number after hci when listing BLE interfaces using the hciconfig command, for example, --ble-device 1 means using hci1 interface. Default: 0.
The BLE device on i.MX 8M Mini EVK is a module based on the NXP 88W8987 Wi-Fi/Bluetooth SoC.
The steps and commands to run any of the examples are quite similar. Thermostat-app is used as an example below.
Prerequisites
By following the Building section of this document, the Yocto image is cross-compiled and programmed to a microSD card.
Follow the steps below to setup the environment needed to run the example on the i.MX 8M Mini EVK:
root via the serial communication program. There is password for the root user in the default Yocto image configuration.scp command on the host machine to copy the executable file to the i.MX 8M Mini EVK.In order to test the CHIP protocol functions, another device on the same network is needed to run the ChipDeviceController tool to communicate with the i.MX 8M Mini EVK.
The ChipDeviceController can be a laptop / workstation. Bluetooth functionality is mandatory on this device.
For the test environment used with this document, a Raspberry Pi is used to run the ChipDeviceController tool.
Follow the steps below to setup the controller environment on a Raspberry Pi:
Running
Initialize the BT device on the i.MX 8M Mini EVK board
$ modprobe moal mod_para=nxp/wifi_mod_para.conf # Load the Wi-Fi/BT firmware $ hciattach /dev/ttymxc0 any 115200 flow # Initialize the BT device
Find the Bluetooth device id for i.MX 8M Mini EVK by executing the command below. The number following string hci is the Bluetooth device id, 0 in this example.
$ hciconfig
hci0: Type: Primary Bus: USB
BD Address: 00:1A:7D:DA:71:13 ACL MTU: 310:10 SCO MTU: 64:8
UP RUNNING
RX bytes:73311 acl:1527 sco:0 events:3023 errors:0
TX bytes:48805 acl:1459 sco:0 commands:704 errors:0
Run the Linux Example App
$ /home/root/thermostat-app --ble-device 0 --wifi # The bluetooth device used is hci0 and support wifi network
Run ChipDeviceController on the controller device to communicate with i.MX 8M Mini EVK running the example.
$ sudo out/python_env/bin/chip-device-ctrl # execute the tool
chip-device-ctrl > connect -ble 3840 20202021 8889 # connect to i.MX 8M Mini EVK
chip-device-ctrl > zcl Thermostat SetpointRaiseLower 8889 1 0 mode=1 amount=10 # send command to i.MX 8M Mini EVK via BLE
(Note that the last two commands connect -ble 3840 20202021 8889 and zcl Thermostat SetpointRaiseLower 8889 1 0 mode=1 amount=10 are Python CHIP Device Controller commands, not shell commands. The 3840 is the target device's discriminator. The 20202021 is the setup pin code. 8889 is the node id and if not input 8889 a random node id will be assigned.)
After the previous commands are executed, inspect the logs of both the i.MX 8M Mini EVK and the controller device to observe connection and control events.
Provision the i.MX 8M Mini EVK to a Wi-Fi AP with the following commands by NetworkCommissioning Cluster.
Command AddWiFiNetwork sends the target Wi-Fi AP's SSID and password. The ${SSID} and ${PASSWORD} should be in plaintext format. At this moment, Wi-Fi is still idle on the i.MX8 Mini EVK.
Command EnableNetwork triggers the Wi-Fi AP connecting operation on i.MX8 Mini EVK.
chip-device-ctrl > zcl NetworkCommissioning AddWiFiNetwork 8889 0 0 ssid=str:${SSID} credentials=str:${PASSWORD} breadcrumb=0 timeoutMs=5000
chip-device-ctrl > zcl NetworkCommissioning EnableNetwork 8889 0 0 networkID=str:${SSID} breadcrumb=0 timeoutMs=15000
Make sure the controller device is connected to the same network of this Wi-Fi AP because the Wi-Fi connection is established between the Wi-Fi AP and the i.MX8 Mini EVK and mDNS only works on local network.
Resolve the target device with DNS-SD and update the address of the node.
chip-device-ctrl > close-ble # Shutdown the BLE connection
chip-device-ctrl > resolve 8889 # The 8889 is the node ID.
chip-device-ctrl > zcl Thermostat SetpointRaiseLower 8889 1 0 mode=1 amount=10 # Now the ZCL command will be send via IP network.