diff --git a/gpio.py b/gpio.py
new file mode 100644
index 0000000..b5f9383
--- /dev/null
+++ b/gpio.py
@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+import sys
+import RPi.GPIO as GPIO
+import time
+import subprocess
+
+GPIO.setmode(GPIO.BCM)
+
+# pins whose states will form the binary number
+PINS = [17, 27, 9, 22]          # MSB → LSB
+
+for p in PINS:
+    try:
+        GPIO.setup(p, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
+    except RuntimeError as e:
+        sys.stderr.write(f"Pin {p} init error: {e}\n")
+        GPIO.cleanup()
+        sys.exit(1)
+
+# read pins, build integer (bit 3 = pin 17, bit 2 = pin 27, bit 1 = pin 22, bit 0 = pin 10)
+old_value=0
+while(True):
+    value = 0
+    for i, p in enumerate(PINS):
+        level = GPIO.input(p)
+        value = (value << 1) | (1 if level else 0)
+    
+    if(value != old_value):
+        #print(f"GPIO states [{', '.join(str(p) for p in PINS)}] -> 0b{value:04b} ({value})")
+        print(str(value))
+        command = "nc -N localhost 12345 < {}.dat".format(value)
+        subprocess.run(command, shell=True, capture_output=False, text=True)
+
+    old_value = value
+    time.sleep(0.1)
+
+    
+GPIO.cleanup()