Raspberry Pi 5 Bench Reference

# the whole header, as it physically sits
pinctrl -P get

# is GPIO17 free, and what is it doing?
pinctrl get 17
#  17: ip    pd | lo // GPIO17 = input
#      ^     ^    ^      ^
#      mode  pull level  current function

Drop these three files on bootfs. This is the whole headless setup without opening Imager's customisation tabs.

#cloud-config
hostname: pi5
manage_etc_hosts: true
timezone: America/New_York

users:
  - name: george
    groups: users,adm,dialout,audio,netdev,video,
            plugdev,gpio,spi,i2c,render,sudo
    shell: /bin/bash
    lock_passwd: false
    # openssl passwd -6   →  paste the $6$... hash here
    passwd: $6$rounds=4096$abc...
    ssh_authorized_keys:
      - ssh-ed25519 AAAAC3Nza... you@laptop
    sudo: ALL=(ALL) NOPASSWD:ALL

rpi:
  i2c: true
  spi: true
  serial: true
  onewire: false

enable_ssh: true

network:
  version: 2
  wifis:
    renderer: NetworkManager
    wlan0:
      dhcp4: true
      optional: true
      regulatory-domain: "US"
      access-points:
        "My Network":
          password: "correcthorsebattery"

# empty is fine, but the file must exist

If cloud-init is not present, these two files still bring up SSH and a user. Wi-Fi you will have to do over Ethernet or a keyboard.

# on bootfs, from your laptop
touch /Volumes/bootfs/ssh

# make a password hash
openssl passwd -6
# Password: ······
# $6$Kx7...

echo 'pi:$6$Kx7...' > /Volumes/bootfs/userconf.txt

# macOS — find the disk, then unmount but don't eject
diskutil list
diskutil unmountDisk /dev/disk4

# rdisk4, not disk4: raw device, ~10x faster
sudo dd if=2025-11-24-raspios-trixie-arm64-lite.img \
        of=/dev/rdisk4 bs=4m status=progress

# Linux
lsblk
sudo dd if=image.img of=/dev/sdX bs=4M conv=fsync status=progress
sync

# from your laptop, once
ssh-keygen -t ed25519 -C "pi5"
ssh-copy-id pi@pi5.local

# then, on the Pi, turn passwords off
sudo sed -i 's/^#*PasswordAuthentication.*/PasswordAuthentication no/' \
  /etc/ssh/sshd_config
sudo systemctl restart ssh

sudo apt install -y \
  i2c-tools python3-smbus2 \        # i2cdetect, i2cget, i2cset
  python3-gpiozero python3-lgpio \  # GPIO from Python
  gpiod \                           # gpioget/gpioset/gpiomon
  git vim tmux htop \
  rsync curl jq \
  raspi-gpio                        # pulls in pinctrl

[pi5]        # Pi 5 only
[cm5]        # CM5 only
[pi4]        # Pi 4 only
[none]       # disable a block without deleting it
[all]        # reset back to everything — always end with this
[HDMI:1]     # settings for the second HDMI port

Space-separated kernel parameters, all on one line. A typical Pi 5 line:

console=serial0,115200 console=tty1 root=PARTUUID=abc12345-02
rootfstype=ext4 fsck.repair=yes rootwait
cfg80211.ieee80211_regdom=US

Pre-installed, works on Pi 5, and is the answer for almost everything.

from gpiozero import LED, Button, PWMLED, MotionSensor
from signal import pause
from time import sleep

led = LED(17)              # BCM numbering, always
led.on(); sleep(1); led.off()
led.blink(on_time=.5, off_time=.5)   # non-blocking
led.toggle()

button = Button(2, pull_up=True, bounce_time=.05)
button.when_pressed  = led.on
button.when_released = led.off
button.wait_for_press()
print(button.is_pressed, button.is_held)

dim = PWMLED(12)
dim.value = 0.35           # 0.0 – 1.0
dim.pulse()

pause()                    # park the main thread on callbacks

RP1's PWM0 has four channels. Two reach the header at ALT0 (GPIO12/13) and two at ALT3 (GPIO18/19). Pi 5 also gains PIO-driven PWM, which works on any GPIO 0–27.

# config.txt — hardware PWM on GPIO12 and GPIO13
dtoverlay=pwm-2chan,pin=12,func=4,pin2=13,func2=4

# after a reboot, find the chip (the number moves between kernels)
ls /sys/class/pwm/
cd /sys/class/pwm/pwmchip0

# 50 Hz, 1.5 ms pulse — a servo's centre
echo 0 | sudo tee export
echo 20000000 | sudo tee pwm0/period       # ns
echo  1500000 | sudo tee pwm0/duty_cycle
echo 1        | sudo tee pwm0/enable

# config.txt
dtoverlay=w1-gpio,gpiopin=4      # default pin is GPIO4

# after reboot — one directory per device
ls /sys/bus/w1/devices/
#  28-3c01d607f0a1   28-xxxx = DS18B20 family

cat /sys/bus/w1/devices/28-*/temperature   # millidegrees C
cat /sys/bus/w1/devices/28-*/w1_slave       # raw, with CRC line

A Pi 5 needs active cooling to hold 2.4 GHz under sustained load. The Active Cooler is ~$5 and it is not optional for anything that runs the CPU hard.

# speed thresholds come down 5 °C on the way back (hysteresis)
# start the fan earlier — config.txt
dtparam=fan_temp0=45000        # millidegrees
dtparam=fan_temp0_hyst=5000
dtparam=fan_temp0_speed=100

# watch it
watch -n1 'vcgencmd measure_temp; \
  cat /sys/class/thermal/thermal_zone0/temp'
cat /sys/devices/platform/cooling_fan/hwmon/hwmon*/fan1_input  # RPM

# a mild, widely-stable overclock — Active Cooler required
#   /boot/firmware/config.txt
arm_freq=2800
over_voltage_delta=50000

# each of these frees 5–40 MB and some boot time
sudo systemctl disable --now bluetooth
sudo systemctl disable --now ModemManager
sudo systemctl disable --now triggerhappy
sudo systemctl disable --now cups cups-browsed
sudo systemctl disable --now avahi-daemon   # ← breaks .local names

# radios off entirely, at the firmware level
#   /boot/firmware/config.txt
dtoverlay=disable-bt-pi5
dtoverlay=disable-wifi-pi5

# cap the journal
sudo mkdir -p /etc/systemd/journald.conf.d
printf '[Journal]\nSystemMaxUse=50M\nStorage=volatile\n' | \
  sudo tee /etc/systemd/journald.conf.d/size.conf
sudo systemctl restart systemd-journald