UART communication

shared/uart_comm.py

@@ -0,0 +1,66 @@
+# shared/uart_comm.py
+import _thread
+from machine import UART
+import time
+
+class SafeUART:
+    def __init__(self, uart_id, tx_pin, rx_pin, baudrate=115200):
+        # Initialize the hardware UART channel
+        self.uart = UART(uart_id, baudrate=baudrate, tx=tx_pin, rx=rx_pin, timeout=10)
+        
+        # Core thread-safety assets
+        self.lock = _thread.allocate_lock()
+        self.rx_queue = []
+        self.buffer = b""
+        
+        # Start the background data worker thread
+        _thread.stack_size(4096) # Cap the stack size for the UART listener
+        _thread.start_new_thread(self._listener_worker, ())
+        _thread.stack_size(0) 
+        
+        print(f"[UART] Thread initialized on UART{uart_id} (TX:{tx_pin}, RX:{rx_pin})")
+
+    def _listener_worker(self):
+        """Asynchronous internal loop parsing incoming stream lines into the queue."""
+        while True:
+            try:
+                if self.uart.any():
+                    with self.lock:
+                        # Pull all raw bytes waiting in the hardware ring buffer
+                        chunk = self.uart.read(self.uart.any())
+                        if chunk:
+                            self.buffer += chunk
+                        
+                        # Process complete lines terminated by a newline character
+                        while b'\n' in self.buffer:
+                            line, self.buffer = self.buffer.split(b'\n', 1)
+                            try:
+                                decoded_line = line.decode('utf-8').strip()
+                                if decoded_line:
+                                    self.rx_queue.append(decoded_line)
+                            except Exception:
+                                pass # Discard corrupt data frames safely
+            except Exception as e:
+                print("[UART Thread Error]:", e)
+                
+            time.sleep_ms(20) # Give other background threads breathing room
+
+    def send(self, message):
+        """Safely pushes strings across the serial wire from any thread context."""
+        if not message.endswith('\n'):
+            message += '\n'
+        
+        with self.lock:
+            self.uart.write(message.encode('utf-8'))
+
+    def any(self):
+        """Checks if any complete messages are waiting to be read."""
+        with self.lock:
+            return len(self.rx_queue) > 0
+
+    def read(self):
+        """Pulls the oldest unread string from the queue. Returns None if empty."""
+        with self.lock:
+            if self.rx_queue:
+                return self.rx_queue.pop(0)
+        return None