added functionality for a second fan on pin 10

app.py

@@ -1,15 +1,10 @@
 #!/usr/bin/env python3
 """
-Flask web UI for ultra-responsive fan control.
-Works with the Arduino sketch above (pin 11 PWM).
+Flask Dual Fan Control – Pin 11 (A), Pin 10 (B)
 """
-
-from flask import Flask, render_template, jsonify, request
-import serial
-import serial.tools.list_ports
-import threading
-import time
-import sys
+from flask import Flask, render_template, jsonify, Response
+import serial, serial.tools.list_ports, threading, time, sys
+from collections import deque
 
 app = Flask(__name__)
 
@@ -24,58 +19,60 @@ def find_arduino():
 
 PORT = find_arduino()
 BAUD = 115200
-
-# Global serial
 ser = None
 serial_lock = threading.Lock()
 
-# -------------------------------------------------
-# Serial init with retry on "busy"
-# -------------------------------------------------
 def init_serial():
     global ser
     for attempt in range(6):
         try:
             ser = serial.Serial(PORT, BAUD, timeout=0)
-            time.sleep(2)  # Arduino reset
+            time.sleep(2)
             print(f"[OK] Connected to {PORT}")
             return
         except serial.SerialException as e:
             if 'Device or resource busy' in str(e):
-                print(f"[BUSY] Port busy, retry {attempt+1}/6 in 1s...")
+                print(f"[BUSY] Retry {attempt+1}/6...")
                 time.sleep(1)
             else:
-                print(f"[ERROR] Serial: {e}")
+                print(f"[ERROR] {e}")
                 sys.exit(1)
-    sys.exit("[FATAL] Could not open serial port after retries")
-
+    sys.exit("[FATAL] Port open failed")
 init_serial()
 
 # -------------------------------------------------
-# Safe send
+# Send command: 'a5', 'bf', 'as', etc.
 # -------------------------------------------------
-def send_command(cmd: str):
+def send_command(fan: str, cmd: str):
+    """fan = 'a' or 'b', cmd = '0'-'9','f','s'"""
+    if fan not in ('a', 'b') or cmd not in '0123456789fs':
+        return
     with serial_lock:
         if ser and ser.is_open:
             try:
+                ser.write(fan.encode())
+                time.sleep(0.001)
                 ser.write(cmd.encode())
                 ser.flush()
             except Exception as e:
                 print(f"[WRITE FAIL] {e}")
 
 # -------------------------------------------------
-# Background reader – pushes feedback to browser via SSE
+# Background reader → SSE
 # -------------------------------------------------
-from collections import deque
-feedback_buffer = deque(maxlen=50)  # last 50 messages
+feedback_buffer = deque(maxlen=50)
 
 def serial_reader():
+    buffer = ""
     while True:
         if ser and ser.in_waiting:
             try:
-                line = ser.readline().decode(errors='ignore').strip()
-                if line:
-                    feedback_buffer.append(line)
+                buffer += ser.read(ser.in_waiting).decode(errors='ignore')
+                while '\n' in buffer:
+                    line, buffer = buffer.split('\n', 1)
+                    line = line.strip()
+                    if line:
+                        feedback_buffer.append(line)
             except:
                 pass
         time.sleep(0.005)
@@ -89,18 +86,15 @@ threading.Thread(target=serial_reader, daemon=True).start()
 def index():
     return render_template('index.html')
 
-@app.route('/cmd/<key>')
-def command(key):
-    if len(key) == 1 and key.lower() in '0123456789fs':
-        send_command(key)
-        return jsonify(status="ok", key=key)
+@app.route('/cmd/<fan>/<key>')
+def command(fan, key):
+    """fan = a|b, key = 0-9,f,s"""
+    if fan in ('a', 'b') and len(key) == 1 and key.lower() in '0123456789fs':
+        send_command(fan, key.lower())
+        return jsonify(status="ok", fan=fan.upper(), key=key.upper())
     return jsonify(status="invalid"), 400
 
-# -------------------------------------------------
-# Server-Sent Events (SSE) – live Arduino feedback
-# -------------------------------------------------
-from flask import Response
-
+# SSE Stream
 @app.route('/stream')
 def stream():
     def event_stream():
@@ -113,11 +107,10 @@ def stream():
             time.sleep(0.05)
     return Response(event_stream(), mimetype="text/event-stream")
 
-# -------------------------------------------------
-# Run
 # -------------------------------------------------
 if __name__ == '__main__':
-    # Accessible from phone/tablet on same WiFi
-    print(f"\nWeb UI: http://YOUR_IP:5000")
-    print("   (Find YOUR_IP with: ip addr show | grep inet)")
+    ip = [l.split()[1] for l in __import__('subprocess')
+          .check_output(["ip", "route"]).decode().splitlines()
+          if 'default' in l][0].split('/')[0]
+    print(f"\nWeb UI: http://{ip}:5000")
     app.run(host='0.0.0.0', port=5000, debug=False, threaded=True)