CHIP Linux Air Quality Example

An example showing the use of CHIP on the Linux. The document will describe how to build and run CHIP Linux Air Quality Example on Raspberry Pi. This doc is tested on Ubuntu for Raspberry Pi Server 20.04 LTS (aarch64) and Ubuntu for Raspberry Pi Desktop 20.10 (aarch64)

To cross-compile this example on x64 host and run on NXP i.MX 8M Mini EVK, see the associated README document for details.

• CHIP Linux Air Quality Example
  • Building
  • Commandline Arguments
  • Running the Complete Example on Raspberry Pi 4
  • Trigger event using air-quality-sensor-app event named pipe

Building

• Install tool chain

    $ sudo apt-get install git gcc g++ python pkg-config libssl-dev libdbus-1-dev libglib2.0-dev ninja-build python3-venv python3-dev unzip
  

• Build the example application:

    $ cd ~/connectedhomeip/examples/air-quality-sensor-app/linux
    $ git submodule update --init
    $ source third_party/connectedhomeip/scripts/activate.sh
    $ gn gen out/debug
    $ ninja -C out/debug
  

• To delete generated executable, libraries and object files use:

    $ cd ~/connectedhomeip/examples/air-quality-sensor-app/linux
    $ rm -rf out/
  

• Build the example with pigweed RPC

    $ cd ~/connectedhomeip/examples/air-quality-sensor-app/linux
    $ git submodule update --init
    $ source third_party/connectedhomeip/scripts/activate.sh
    $ gn gen out/debug --args='import("//with_pw_rpc.gni")'
    $ ninja -C out/debug
  

Commandline arguments

• --wifi

  Enables WiFi management feature. Required for WiFi commissioning.

• --thread

  Enables Thread management feature, requires ot-br-posix dbus daemon running. Required for Thread commissioning.

• --ble-device <interface id>

  Use specific bluetooth interface for BLE advertisement and connections.

  interface id: the number after hci when listing BLE interfaces by hciconfig command, for example, --ble-device 1 means using hci1 interface. Default: 0.

Running the Complete Example on Raspberry Pi 4

gn gen out/debug
ninja -C out/debug

• Prerequisites

  1. A Raspberry Pi 4 board
  2. A USB Bluetooth Dongle, Ubuntu desktop will send Bluetooth advertisement, which will block CHIP from connecting via BLE. On Ubuntu server, you need to install pi-bluetooth via APT.
  3. Ubuntu 20.04 or newer image for ARM64 platform.

• Building

  Follow Building section of this document.

• Running

  • [Optional] Plug USB Bluetooth dongle

    • Plug USB Bluetooth dongle and find its bluetooth device number. The number after hci is the bluetooth device number, 1 in this example.

        $ hciconfig
        hci1:	Type: Primary  Bus: USB
            BD Address: 00:1A:7D:AA:BB:CC  ACL MTU: 310:10  SCO MTU: 64:8
            UP RUNNING PSCAN ISCAN
            RX bytes:20942 acl:1023 sco:0 events:1140 errors:0
            TX bytes:16559 acl:1011 sco:0 commands:121 errors:0
      
        hci0:	Type: Primary  Bus: UART
            BD Address: B8:27:EB:AA:BB:CC  ACL MTU: 1021:8  SCO MTU: 64:1
            UP RUNNING PSCAN ISCAN
            RX bytes:8609495 acl:14 sco:0 events:217484 errors:0
            TX bytes:92185 acl:20 sco:0 commands:5259 errors:0
      

    • Run Linux Air Quality Example App

        $ cd ~/connectedhomeip/examples/air-quality-sensor-app/linux
        $ sudo out/debug/chip-air-quality-sensor-app --ble-device [bluetooth device number]
        # In this example, the device we want to use is hci1
        $ sudo out/debug/chip-air-quality-sensor-app --ble-device 1
      

    • Test the device using ChipDeviceController on your laptop / workstation etc.

Trigger event using air-quality-sensor-app event named pipe

You can send a command to air-quality-sensor-app to trigger specific event via air-quality-sensor-app event named pipe /tmp/chip_air_quality_fifo*.

Trigger air quality change event

Generate event AirQuality, to change the air quality value.

$ echo '{"Name":"AirQuality","NewValue":3}' > /tmp/chip_air_quality_fifo_<PID>

Trigger Temperature change event

Generate event TemperatureMeasurement, to change the temperate value.

$ echo '{"Name":"TemperatureMeasurement","NewValue":18}' > /tmp/chip_air_quality_fifo_<PID>

Trigger Humidity change event

Generate event RelativeHumidityMeasurement, to change the temperate value.

$ echo '{"Name":"RelativeHumidityMeasurement","NewValue":60}' > /tmp/chip_air_quality_fifo_<PID>

Trigger concentration change event

Concentration change events can be trigger on the concentration measurement clusters.

Generate event CarbonDioxideConcentrationMeasurement, to change the CO2 value.

$ echo '{"Name":"CarbonDioxideConcentrationMeasurement","NewValue":400}' > /tmp/chip_air_quality_fifo_<PID>