Raspberry Pi - Display IP address on LCD module on boot

lcd_first_boot.py

import time
import netifaces
from RPLCD.i2c import CharLCD
import fcntl

# --- Configuration ---
WIFI_IFACE = "wlan0"
LCD_I2C_ADDR = 0x27
LOCK_FILE = "/tmp/lcd.lock"

# --- LCD Setup ---
lcd = CharLCD(i2c_expander="PCF8574", address=LCD_I2C_ADDR, cols=16, rows=2, charmap="A00", auto_linebreaks=False)
lcd.clear()


# --- Helper Functions ---
def get_ip_address(interface=WIFI_IFACE):
	"""Return the IPv4 address of the interface, or None if not up."""
	try:
		addrs = netifaces.ifaddresses(interface)
		if netifaces.AF_INET in addrs:
			return addrs[netifaces.AF_INET][0]['addr']
	except (ValueError, KeyError):
		return None
	return None


def safe_lcd_write(lines):
	"""Write to LCD safely using a file lock."""
	with open(LOCK_FILE, "w") as lockfile:
		fcntl.flock(lockfile, fcntl.LOCK_EX)
		lcd.clear()
		for i, line in enumerate(lines):
			if i > 1:  # LCD has only 2 lines
				break
			lcd.cursor_pos = (i, 0)
			lcd.write_string(line)
		fcntl.flock(lockfile, fcntl.LOCK_UN)


def display_connecting():
	safe_lcd_write(["Connecting to", WIFI_IFACE])


def display_ip(ip):
	safe_lcd_write(["Connected", ip])


# --- LCD Update Loop ---
def lcd_update_loop():
	display_connecting()
	while True:
		ip = get_ip_address()
		if ip:
			display_ip(ip)
			break
		time.sleep(1)


# --- Run ---
lcd_update_loop()