Raspberry Pi 4

• All the commands below are tested under Debian Buster 10

Wpa_supplicant.conf

• For a fresh OS, you may need to create or edit the wpa_supplicant.conf in order for the Raspi to be connected to Wifi after its startup

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
ap_scan=1
update_config=1

network={
    ssid="<Name of your wireless LAN>"
    psk="<Password for your wireless LAN>"
}

Clean up space

• Sometimes, you would like to clean up space of SD card

• You can uninstall some unnecessary package and do some cleaning

$ sudo apt-get purge wolfram-engine libreoffice* scratch -y
$ sudo apt-get clean
$ sudo apt-get autoremove -y

Enable I2C

• go to /boot/config.txt and change to the following:

# Uncomment some or all of these to enable the optional hardware interfaces
dtparam=i2c_arm=on
#dtparam=i2s=on
#dtparam=spi=on

Detect I2C

• Install tools for I2C

$ sudo apt-get install -y i2c-tools

• Scan I2C devices

$ sudo i2cdetect -y 1

Enable UART1

• To enable UART, go to /boot/cmdline.txt and removed the line "console=serial0,115200"

• It should become like the following:

console=tty1 root=/dev/mmcblk0p7 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait quiet splash plymouth.ignore-serial-consoles

• go to /boot/config.txt and add

[all]
enable_uart=1

$ sudo systemctl stop [e-mail]
$ sudo systemctl disable [e-mail]

Use default uart TX0, RX0

$ sudo chmod 0666 /dev/ttyS0

Disable MAC address randomization

• To bind your Raspi to static ip address assigned by router, you would hope the MAC address is always the same for the Raspi.

• To avoid randomization, create file at /etc/NetworkManager/conf.d/100-disable-wifi-mac-randomization.conf

[connection]
wifi.mac-address-randomization=1

[device]
wifi.scan-rand-mac-address=no

References

1. https://learn.adafruit.com/adafruits-raspberry-pi-lesson-4-gpio-setup/configuring-i2c