KNoT Network of Things - Gateway

This is the gateway software module for the KNoT platform. It is based on Buildroot 2018.08 version for RaspberryPi hardware.

Buildroot is a simple, efficient and easy-to-use tool to generate embedded Linux systems through cross-compilation.

Buildroot online documentation can be found at http://buildroot.org/docs.html

System requirements

Buildroot is designed to run on Linux systems. If you are using a Mac, there is an experimental Vagrant box configured to build the KNoT Gateway, see HACKING.rst file on directory.

While Buildroot itself will build most host packages it needs for the compilation, certain standard Linux utilities are expected to be already installed on the host system. Below you will find an overview of the mandatory and optional packages.

Install the required packages:

The following command is for Debian based Linux distro, such as Ubuntu. Note that package manager and package names may vary between distributions

sudo apt-get install build-essential automake \
         libtool pkg-config g++ flex gawk bc bzr cvs git \
         mercurial subversion cpio locales libssl-dev \
         libncurses5-dev libssl-dev libncurses5-dev zlib1g \
         libncurses5 wget unzip autoconf-archive libdbus-1-dev

How to Build it

The knot_<board>_defconfig configuration is a minimal configuration with all that is required to bring the KNoT platform on RaspberryPi.

Warning: You will need to have access to the network, since Buildroot will download the packages' sources. For an offline build see HACKING.rst file.

You should base your work on this defconfig:

Run KNoT defconfig
```
make knot_<board>_defconfig
```
Note: Currently supported KNoT defconfigs:
- knot_raspberrypi3_defconfig
- knot_raspberrypi0w_defconfig
Additionally, the following defconfigs are available to work with KNoT v03:
- knot_v03_rpi3_defconfig
- knot_v03_rpi0w_defconfig
Note: The KNoT v03 is still not compatible with nRF's Things.
Menu Configuration

You can access and select extra packages you wish to compile with KNoT Linux OS on Buildroot menuconfig. This is an optional step.
```
make menuconfig
```
Build
```
make
```
Tip: This may take a while. Consider getting yourself a coffee ;-)

Result of the build

After building, you should obtain this tree:

output/images/
├── bcm2708-rpi-b.dtb           [1]
├── bcm2708-rpi-b-plus.dtb      [1]
├── bcm2708-rpi-0-w             [1]
├── bcm2709-rpi-2-b.dtb         [1]
├── bcm2710-rpi-3-b.dtb         [1]
├── bcm2710-rpi-3-b-plus.dtb    [1]
├── boot.vfat
├── rootfs.ext4
├── rpi-firmware/
|   ├── bootcode.bin
|   ├── cmdline.txt
|   ├── config.txt
|   ├── fixup.dat
|   ├── start.elf
|   └── overlays/               [2]
├── sdcard.img
└── zImage

[1] Not all of them will be present, depending on the RaspberryPi model you are using.

[2] Only for the Raspberry Pi 3 Model (overlay pi3-miniuart-bt is needed to enable the RPi3 serial console otherwise occupied by the bluetooth chip). Alternative would be to disable the serial console in cmdline.txt and /etc/inittab.

How to write the SD card

Once the build process is finished you will have an image called sdcard.img in the output/images/ directory.

It is possible to erase and write the SD Card using native OS application to manage and configure disk drives. Similarly to Disks on Ubuntu.

If you are using a Linux based distribution you can use dd command.
Copy the bootable sdcard.img onto an SD card with dd:
```
sudo dd if=output/images/sdcard.img of=/dev/sdX status=progress
```
Note: status=progress is an optional argument to show the progress of the command execution. See dd manual for more options.
A user friendly way to flash the image is using balenaEtcher. You can use any OS to flash using balenaEtcher.
1. Download and install balenaEtcher.
2. Connect an SD card to your computer.
3. Open balenaEtcher and select sdcard.img file.
4. Select the target SD card.
5. Flash it.

After a successful flash, insert the SD Card into your Raspberry Pi, and power it up.

Monitoring the KNoT Gateway image

You can access you gateway using ssh command.

In a linux machine on same local network and execute the followed command on terminal:

arp-scan -l | grep b8:27:eb

Note: It is necessary to have arp-scan package installed. If you're running a Ubuntu/Debian based distro, run sudo apt-get install arp-scan on terminal.

Another way is connecting a screen and a keyboard on Raspberry Pi, login as user root and password root, and type the command below on terminal:

ip a

This commands will return the IP address the router have assigned to the KNot gateway.

To access the gateway using ssh, run the followed command in a linux machine on same local network:

ssh root@<raspberry-IP>

The password is root

Contact

Get the contact information on the Contact section of KNoT documentation.