added web-ui-control

drive/opt/drive-ctl/server.py

@@ -0,0 +1,65 @@
+import asyncio
+import json
+import time
+import serial
+from fastapi import FastAPI, WebSocket, WebSocketDisconnect
+from fastapi.responses import HTMLResponse
+
+SERIAL_PORT = "/dev/ttyACM0"   # ggf. /dev/ttyUSB0
+BAUD = 115200
+
+# Safety: if websocket stops sending, we also stop.
+STOP_AFTER_SEC = 0.35
+
+app = FastAPI()
+
+ser = serial.Serial(SERIAL_PORT, BAUD, timeout=0)
+
+last_msg_ts = 0.0
+
+def clamp255(v: int) -> int:
+  return max(-255, min(255, int(v)))
+
+def send_lr(l: int, r: int):
+  l = clamp255(l)
+  r = clamp255(r)
+  line = f"L {l} R {r}\n".encode("ascii")
+  ser.write(line)
+
+@app.get("/health")
+def health():
+  return {"ok": True, "serial": SERIAL_PORT}
+
+@app.websocket("/ws")
+async def ws(websocket: WebSocket):
+  global last_msg_ts
+  await websocket.accept()
+
+  async def watchdog():
+    while True:
+      await asyncio.sleep(0.05)
+      if time.time() - last_msg_ts > STOP_AFTER_SEC:
+        send_lr(0, 0)
+
+  wd_task = asyncio.create_task(watchdog())
+
+  try:
+    while True:
+      msg = await websocket.receive_text()
+      last_msg_ts = time.time()
+
+      try:
+        data = json.loads(msg)
+        l = clamp255(data.get("l", 0))
+        r = clamp255(data.get("r", 0))
+        send_lr(l, r)
+      except Exception:
+        # On parse errors: stop
+        send_lr(0, 0)
+
+      await websocket.send_text("ok")
+  except WebSocketDisconnect:
+    send_lr(0, 0)
+  finally:
+    wd_task.cancel()
+