Prototyping IoT with Pierre Ficheux (pierre.ficheux@smile.fr) - - PowerPoint PPT Presentation

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Prototyping IoT with Pierre Ficheux (pierre.ficheux@smile.fr) - - PowerPoint PPT Presentation

Aug 18, 2023 563 likes •851 views

Prototyping IoT with Pierre Ficheux (pierre.ficheux@smile.fr) 02/2017 Prototyping IoT with Yocto 1 $ whoami French embedded Linux developer, writer and teacher CTO @ Smile-ECS (Embedded & Connected Systems) Prototyping IoT with

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1 Prototyping IoT with Yocto

Prototyping IoT with

Pierre Ficheux (pierre.ficheux@smile.fr) 02/2017

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2 Prototyping IoT with Yocto

$ whoami

  • French embedded Linux developer, writer and teacher
  • CTO @ Smile-ECS (Embedded & Connected Systems)
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3 Prototyping IoT with Yocto

2 kinds of objects

  • Basic one such as sensor

– MCU/µC (no MMU) – Software is « bare metal » or light OS such as Contiki

  • r RIOT
  • Advanced one (computer like)

– CPU with MMU (32 bits or more) – OS such as Linux / Tizen / Android

Parrot flower power (µC) Eccelenza touch (Yocto) “Tesla car is a connected computer on wheels !”

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4 Prototyping IoT with Yocto

Linux and IoT

  • Not “the” universal OS for IoT but...
  • According to “IoT developer Survey 2016”

– 73 % Linux – 23 % « bare metal » (no OS) – 12 % FreeRTOS – 6 % Contiki

  • Don't forget there are and

– Distribution (Debian, Ubuntu, etc.) – « Build system » (Yocto, Buildroot, etc.)

  • Today most of objects are computers
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5 Prototyping IoT with Yocto

Linux distribution

  • Most of developers use Linux distribution
  • Well known, comfortable and portable environment but

– High footprint (Go) – boot time (close to 1 mn) – Development oriented → host but not a target – No traceability (binaries) – Limited target support (x86, ARM) – Not for IoT at all !!

  • Most distributions runs on ARM → easy to take a wrong

way

  • Alternate – and right - way is « build system » !
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6 Prototyping IoT with Yocto

What is a « build system » ?

  • Not a distribution, just a tool to build one from sources
  • Does not provide sources but “recipes”
  • Provides binaries file to be installed on the target

– Bootloader – Linux kernel and DT blobs – Root-filesystem image + applications

  • Provides additional information

– Licensing – Dependencies graphs

  • Much better footprint, boot time, etc.
  • Android uses a dedicated – but open source - build

systems

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7 Prototyping IoT with Yocto

Most famous build systems

  • Yocto/OpenEmbedded

– Based on “BitBake” (Python) – Very powerful, not that easy to learn – Text oriented

  • Buildroot

– Based on standard GNU Make – Started as an internal tool for uClibc – Static approach (no packages)

  • OpenWrt

– Modified Buildroot – Packaging support – Used for WeIO (IoT device)

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8 Prototyping IoT with Yocto

Buildroot

  • Formerly internal tool for uClibc
  • One version every 3 months since 2009.02
  • Kernel like graphical configurator
  • Fast and easy to use
  • Result is not a distribution but a “Linux firmware”
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9 Prototyping IoT with Yocto

OpenEmbedded

  • A “cross compilation framework”
  • Started Chris Larson, Michael Lauer et Holger Schuring

for “OpenZaurus” (2002)

  • Zaurus (SHARP) was the “first” Linux/Qt PDA
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10 Prototyping IoT with Yocto

OE principles

  • Recipe is a .bb (for BitBake) file for every component

(from “Hello World” to whole distribution)

  • OE uses classes (.bbclass), headers (.inc) and

configuration files (.conf)

  • You can inherit from class with inherit
  • “Deriving” a recipe is VERY useful → .bbappend
  • Files are organized as “layers” → meta-*
  • OE data flow is based on packages (RPM, IPK, DEB)
  • Package management on target is optional
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11 Prototyping IoT with Yocto

Yocto / OE

  • Yocto (symbol y) is a unit prefix in the metric system

denoting a factor of 10-24

  • Yocto project was started in 2010 by Linux foundation
  • Sub-projects integration (OE, BitBake, Poky, etc.)
  • Currently most of embedded companies and hardware

makers are members (Intel, Montavista, NXP, TI, etc.)

  • Richard Purdie (Linux Foundation fellow) is the

architect

  • Most of Linux BSP are provided as OE layers !
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12 Prototyping IoT with Yocto

Yocto / OE workflow

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13 Prototyping IoT with Yocto

Yocto / OE layers

IoT layer

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14 Prototyping IoT with Yocto

Yocto/Poky « in a nutshell »

  • Installing Poky and BSP

$ git clone -b krogoth git://git.yoctoproject.org/poky $ cd poky $ git clone git://git.yoctoproject.org/meta-raspberrypi

  • Creating working directory

$ source oe-init-build-env rpi-build

  • Adding BSP layer to conf/bblayers.conf

$ bitbake-layers add-layer meta-raspberrypi

  • Adding target name to conf/local.conf

MACHINE = "raspberrypi"

  • Creating minimal image

$ bitbake core-image-minimal

  • Testing on SD card

$ sudo dd if=<path>/core-image-minimal-raspberrypi.rpi-sdimg

  • f=/dev/sdb
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15 Prototyping IoT with Yocto

Use case 1 : IoT sensor

  • Building a demo sensor for Smile

– Raspberry Pi (zero) – I²C temperature/pressure sensor (MPL115A2) – Wi-Fi (USB) – HTTP protocol

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16 Prototyping IoT with Yocto

Demonstrator global architecture

sensor

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17 Prototyping IoT with Yocto

Building distribution

  • Starting from smaller distro « core-image-minimal »
  • Adding options and new recipes

– Package management – Standard or “derivated” recipes – New recipes (I²C sensor control)

  • Put everything in a new layer → meta-iot

$ yocto-layer create iot

  • Updating local.conf (for test only)
  • Creating a new distro recipe → « rpi-iot-image »
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18 Prototyping IoT with Yocto

Using .bbappend (derivation)

  • One recipe (.bb) is defined in layer “A”
  • We update recipe in a .bbappend located in layer “B”
  • Currently

– Network configuration (Wi-Fi + HTTPd) – I²C activation in config.txt – Autoload of i2c-dev module

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19 Prototyping IoT with Yocto

Wi-Fi + HTTPd

  • Wi-Fi adapter is supported → wlan0
  • We need some additional packages (Wi-Fi management +

HTTP server=

IMAGE_INSTALL_append += "iw wpa_supplicant lighttpd"

  • Updating /etc/network/interfaces for wlan0

automatic configuration

  • WPA authentication (manual procedure for test)

# wpa_passphrase <ESSID> <password> > /etc/wpa_supplicant.conf # ifdown wlan0 # ifup wlan0

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20 Prototyping IoT with Yocto

Sensor + I²C

  • Updating config.txt

dtparam=i2c_arm=on

→ do_deploy_append()

  • Adding packages to local.conf

IMAGE_INSTALL_append += "i2c-tools kernel-modules"

  • Loading I²C support

KERNEL_MODULE_AUTOLOAD += "i2c-dev"

→ Kernel .bbappend

  • New recipe for MPL115A2 control

– Adapting original program (C, based on WiringPi) – Starting a “service”, reading sensor every 20 secs

→ using update-rc.d class

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21 Prototyping IoT with Yocto

NTP support

  • No RTC on Raspberry Pi
  • NTP recipe provided by meta-openembedded layer

$ cd poky $ git clone git://git.openembedded.org/meta-openembedded $ git checkout <yocto-branch> $ bitbake-layers add-layer ../meta-openembedded/meta-oe $ bitbake-layers add-layer ../meta-openembedded/meta-python $ bitbake-layers add-layer ../meta-openembedded/meta-networking $ bitbake ntp tzdata

  • Configuring timezone

# rm -f /etc/localtime # ln -s /usr/share/zoneinfo/Europe/Paris /etc/localtime # cat /etc/default/ntpdate ... NTPSERVERS="pool.ntp.org"

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22 Prototyping IoT with Yocto

Updading target

  • SMART included by package management
  • Creating packages index

$ bitbake package-index

  • Creating HTTP channels on the target

# smart channel --add <channel> baseurl=http://<pkg-dir> # smart update # smart install ntpdate tzdata

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23 Prototyping IoT with Yocto

Use case 2 : Border router (N. Aguirre)

  • More complex demonstration based on sensorTag (TI)
  • Raspberry Pi (Yocto 2.1 based) as “border router”
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24 Prototyping IoT with Yocto

SensorTag

  • Cortex M3 (48MHz, 128KB flash, 8KB RAM)
  • 512KB external flash for OTA and/or storage
  • Low-power (10 mA active, 100 uA sleeping)
  • Radio802.15.4 + Bluetooth Low Energy (BLE)
  • $ 30 from TI website
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25 Prototyping IoT with Yocto

Raspberry Pi + 6LBR

  • 6LBR est a board router software (between IoT/sensors

world and Internet world)

  • Get data from SensorTags (6LoWPAN)
  • Send data to the “cloud”
  • MQTT broker
  • Time Series (Influxdb) database
  • MQTT / database connector (Telegraf)
  • Web management and display (Grafana)
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26 Prototyping IoT with Yocto

Grafana display

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27 Prototyping IoT with Yocto

Références

  • http://elinux.org/Build_Systems
  • https://www.yoctoproject.org/
  • http://buildroot.uclibc.org
  • http://iot.ieee.org/images/files/pdf/iot-developer-survey-2016-report-final.pdf
  • https://openwrt.org
  • http://eccellenzatouchvki.com
  • http://www.parrot.com/fr/produits/flower-power
  • https://www.yoctoproject.org/ecosystem/iot
  • http://we-io.net/hardware
  • https://github.com/nodesign/weioBoard
  • https://www.raspberrypi.org/documentation/hardware/raspberrypi/schematics/README.md
  • http://www.ti.com/ww/en/wireless_connectivity/sensortag2015