Raspberry Pi Setup Notes

These notes are based on an install of the 32-bit Raspberry Pi OS Lite.

User Permissions

Note that this shouldn’t be required - by default the pi user is in the dialout, gpio, i2c and spi groups.

sudo usermod -a -G dialout pi
sudo usermod -a -G i2c pi

Development Libraries and Tools

sudo apt -y install i2c-tools libi2c-dev gpiod libgpiod2 libgpiod-dev avahi-daemon gcc make unzip zip vim git
sudo apt -y install pigpio-tools libpigpiod-if-dev libpigpiod-if2-1

Java

sudo apt -y install openjdk-11-jdk

ZSH

sudo apt install zsh
chsh -s /usr/bin/zsh
sh -c "$(curl -fsSL https://raw.github.com/ohmyzsh/ohmyzsh/master/tools/install.sh)"

Make a minor tweak to the robbyrussell theme to show the hostname in the command prompt:

cd ~/.oh-my-zsh/themes
cp robbyrussell.zsh-theme robbyrussell_tweak.zsh-theme

Edit robbyrussell_tweak.zsh-theme and change the PROMPT value to include this prefix %{$fg_bold[white]%}%M%{$reset_color%} :

PROMPT="%{$fg_bold[white]%}%M%{$reset_color%} %(?:%{$fg_bold[green]%}➜ :%{$fg_bold[red]%}➜ )"

Update the ZSH config ~/.zshrc:

export PATH=$PATH:/sbin:/usr/sbin:/usr/local/sbin
export JAVA_HOME=/usr/lib/jvm/java-11-openjdk-armhf

ZSH_THEME="robbyrussell_tweak"

My own preference is to add this to the end of the .zshrc file:

# Allow multiple terminal sessions to all append to one zsh command history
setopt APPEND_HISTORY
# Do not enter command lines into the history list if they are duplicates of the previous event
setopt HIST_IGNORE_DUPS
# Remove command lines from the history list when the first character on the line is a space
setopt HIST_IGNORE_SPACE
# Remove the history (fc -l) command from the history list when invoked
setopt HIST_NO_STORE

Check I2C Clock Speed

#!/bin/sh
# Print current maximum i2c rate
var="$(xxd /sys/class/i2c-adapter/i2c-1/of_node/clock-frequency | awk -F': ' '{print $2}')"
var=${var//[[:blank:].\}]/}
printf "I2C Clock Rate: %d Hz\n" 0x$var

Hardware PWM

All Raspberry Pi models have at least one hardware PWM channel as per the table below.

These values were taken from the file /boot/overlays/README.

By default, configuring the hardware PWM channel is only possible via relatively complex memory-mapped register configuration which require root access to modify. Fortunately pigpio can handle all of this complexity for us - full hardware PWM control is available via the pigpioj provider.

Hardware PWM control is also possible via the Linux sysfs interface. To enable one hardware PWM channel add dtoverlay=pwm to /boot/config.txt (using the GPIO and Func values in the table above) and reboot. For example, to enable hardware PWM channel 0 on GPIO 12:

dtoverlay=pwm,pin=12,func=4

After a reboot the sysfs directory /sys/class/pwm/pwmchip0/pwm0 should be present.

Alternatively, two hardware PWM channels can be configured by adding dtoverlay=pwm-2chan to /boot/config.txt. For example, to enable hardware PWM channel 0 on GPIO 18 and channel 1 on 19:

dtoverlay=pwm-2chan,pin=18,func=2,pin2=19,func2=2

Make sure you add only one of the above and verify that the settings are correct before rebooting.