Raspberry Pi 5 Buildroot Project

This project provides a Buildroot-based environment for the Raspberry Pi 5, including WiFi support, networking tools, and integration with the BCM2835 library for sensor interaction.

Author

Carlos Alvarado Martinez

Wiki Pages

• Overview
• Schedule

Prerequisites

The following resources are required for this project:

• A Raspberry Pi 5
• Access to the Buildroot repository, branch 2024.08.x
• A Linux-based build environment with Git

Project Setup

1. Clone the Buildroot Repository

Clone the Buildroot repository and check out the 2024.08.x branch:

git clone https://github.com/buildroot/buildroot.git
cd buildroot
git checkout 2024.08.x

2. Configure Buildroot for the Raspberry Pi 5

Load the Raspberry Pi 5 default configuration:

make raspberrypi5_defconfig

This configuration provides a base setup for the Raspberry Pi 5; however, additional configurations are necessary to support WiFi, network tools, and sensor functionality.

3. Enable WiFi Support

To enable WiFi, perform the following steps:

1. Enable Firmware:

   • Navigate to Target packages > Hardware handling > Firmware.
   • Select the following options:

     [*] linux-firmware
       [*] rpi-wifi-firmware

2. Add Wireless Tools:

   • Go to Target packages > Networking applications.
   • Enable the following packages:

     [*] wireless_tools
     [*] wpa_supplicant
       [*] Enable nl80211 driver
       [*] Enable WPA2

4. Configure DHCP Client

Ensure that dhclient is available to obtain an IP address automatically:

1. Install dhclient:
   • Navigate to Target packages > Networking applications and enable dhclient.

5. Set Up the BCM2835 Library for Sensor Integration

The BCM2835 library enables low-level access to the Raspberry Pi’s GPIO pins and hardware features, which is essential for sensor functionality.

1. Download the BCM2835 Library:

   • Obtain the library from the official BCM2835 Library website.

2. Configure the Buildroot Overlay:

   • Integrate the BCM2835 library source files into the Buildroot overlay or compile and install it manually after Buildroot setup:

     ./configure
     make
     sudo make install

3. Add the Library Path:

   • Ensure that the path to the BCM2835 library is correctly specified in application build scripts to facilitate sensor interaction.

6. Automate WiFi Connection on Boot

To automate the WiFi startup process, a script named wifi_startup.sh can be created. This script should be placed in base_external/rootfs_overlay/etc/init.d/ in the Buildroot overlay.

WPA_CONF="/etc/wpa_supplicant.conf"

case "$1" in
  start)
    echo "Starting WiFi..."
    # Ensure WiFi interface is up
    ifconfig wlan0 up
    # Start wpa_supplicant with the specified configuration file
    wpa_supplicant -B -i wlan0 -c "$WPA_CONF"
    # Obtain IP via DHCP
    dhclient wlan0
    ;;
  stop)
    echo "Stopping WiFi..."
    # Stop wpa_supplicant
    killall wpa_supplicant
    # Release DHCP
    dhclient -r wlan0
    ;;
  restart)
    $0 stop
    sleep 3
    $0 start
    ;;
  *)
    echo "Usage: $0 {start|stop|restart}"
    exit 1
    ;;
esac

exit 0

• Place this file in base_external/rootfs_overlay/etc/init.d/S99wifi_startup.

7. Exclude WiFi Credentials from Version Control

To prevent committing WiFi credentials, add wpa_supplicant.conf to .gitignore:

base_external/rootfs_overlay/etc/wpa_supplicant.conf

8. Build the Project

Once all configurations are complete, build the project:

make

Flashing the SD Card

After building, flash the generated image to an SD card:

sudo dd if=output/images/sdcard.img of=/dev/sdX bs=4M
sync

Replace /dev/sdX with the actual device identifier for the SD card.

Running on the Raspberry Pi 5

Insert the SD card into the Raspberry Pi 5, power it on, and it will automatically connect to WiFi and enable BCM2835-based sensor integration.