initial python serial repl

serial_repl.py

@@ -0,0 +1,82 @@
+import serial
+import threading
+from time import sleep
+
+class SelfHealingSerial():
+    """A wrapper class for pyserial's Serial class
+
+    This reimplements the basic Serial functions but wraps them in _reestablish_and_retry.
+    This attempts a reconnect if the arduino is unplugged or otherwise unavailable.
+
+    Also this has defaults that work with the Adafruit M0 LoRa feather.
+    """
+    def __init__(self, path: str = '/dev/ttyACM0', baudrate: int = 115200, timeout: int = 2):
+        self._path = path
+        self._baudrate = baudrate
+        self._timeout = timeout
+        self._connection = None
+        self._waiting_response = False
+
+    def _establish_connection(self):
+        """Connects to the feather
+        """
+        self._connection = serial.Serial(self._path, self._baudrate, timeout=self._timeout)
+
+    def _reestablish_and_retry(func):
+        """If disconnect, keep trying every second
+
+        We know if there's a disconnect when the attempted function fails.
+        """
+        def wrapper(self: "SelfHealingSerial", *args, **kwargs):
+            while True:
+                try:
+                    if not self._connection:
+                        self._establish_connection()
+                    return func(self, *args, **kwargs)
+                except (IOError, serial.serialutil.SerialException):
+                    print("Connection failed.")
+                    sleep(1)
+                    print("Reestablishing connection.")
+                    self._connection = False
+        return wrapper
+
+    @_reestablish_and_retry
+    def read_all(self):
+        """Read all data from the serial port
+        """
+        return self._connection.read_all()
+
+    @_reestablish_and_retry
+    def write(self, bytestring: bytes):
+        """Write to the serial port
+        """
+        self._waiting_response = True
+        return self._connection.write(bytestring)
+
+def print_serial(serial_obj: SelfHealingSerial):
+    """Check for new serial output and print it to the terminal
+    """
+    while True:
+        line = serial_obj.read_all()
+        if line:
+            serial_obj._waiting_response = False
+            print("\n" + line.decode() + "\n>>>", end="")
+
+def write_serial(serial_obj: SelfHealingSerial):
+    """If we're not waiting for a response, write data to the serial port, then wait for a response.
+    """
+    while True:
+        if not serial_obj._waiting_response:
+            send_string = input("")
+            if send_string and send_string != '\n' and send_string != '\r\n':
+                serial_obj.write(send_string.encode('utf-8'))
+        else:
+            sleep(1)
+
+if __name__ == "__main__":
+    connection: SelfHealingSerial = SelfHealingSerial('/dev/ttyACM0', 115200, timeout=1)
+    listen_thread = threading.Thread(target=print_serial, args=(connection,))
+    listen_thread.start()
+    print(">>> ", end="")
+
+    write_serial(connection)