279 lines
8.6 KiB
Python
279 lines
8.6 KiB
Python
import base64
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import json
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import serial
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import threading
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import time
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from platypush.plugins import action
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from platypush.plugins.sensor import SensorPlugin
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class SerialPlugin(SensorPlugin):
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"""
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The serial plugin can read data from a serial device, as long as the serial
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device returns a JSON. You can use this plugin to interact for example with
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some sensors connected through an Arduino. Just make sure that the code on
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your serial device returns JSON values. If you're using an Arduino or any
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ATMega compatible device, take a look at
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https://github.com/bblanchon/ArduinoJson.
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"""
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def __init__(self, device=None, baud_rate=9600, **kwargs):
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"""
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:param device: Device path (e.g. ``/dev/ttyUSB0`` or ``/dev/ttyACM0``)
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:type device: str
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:param baud_rate: Serial baud rate (default: 9600)
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:type baud_rate: int
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"""
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super().__init__(**kwargs)
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self.device = device
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self.baud_rate = baud_rate
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self.serial = None
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self.serial_lock = threading.Lock()
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self.last_measurement = None
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def _read_json(self, serial_port):
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n_brackets = 0
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is_escaped_ch = False
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parse_start = False
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output = bytes()
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while True:
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ch = serial_port.read()
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if not ch:
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break
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try:
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ch.decode()
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except Exception as e:
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self.logger.warning('Could not decode character: {}'.format(str(e)))
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output = bytes()
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if ch.decode() == '{' and not is_escaped_ch:
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parse_start = True
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n_brackets += 1
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if not parse_start:
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continue
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output += ch
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if ch.decode() == '}' and not is_escaped_ch:
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n_brackets -= 1
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if n_brackets == 0:
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break
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is_escaped_ch = ch.decode() == '\\'
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return output.decode().strip()
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def _get_serial(self, device=None, baud_rate=None, reset=False):
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if not device:
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if not self.device:
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raise RuntimeError('No device specified nor default device configured')
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device = self.device
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if baud_rate is None:
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if self.baud_rate is None:
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raise RuntimeError('No baud_rate specified nor default configured')
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baud_rate = self.baud_rate
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if self.serial:
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if not reset:
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return self.serial
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self._close_serial()
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self.serial = serial.Serial(device, baud_rate)
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return self.serial
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def _close_serial(self):
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if self.serial:
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try:
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self.serial.close()
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self.serial = None
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except Exception as e:
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self.logger.warning('Error while closing serial communication: {}')
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self.logger.exception(e)
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@action
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def get_measurement(self, device=None, baud_rate=None):
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"""
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Reads JSON data from the serial device and returns it as a message
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:param device: Device path (default: default configured device)
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:type device: str
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:param baud_rate: Baud rate (default: default configured baud_rate)
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:type baud_rate: int
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"""
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if not device:
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if not self.device:
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raise RuntimeError('No device specified nor default device configured')
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device = self.device
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if baud_rate is None:
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if self.baud_rate is None:
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raise RuntimeError('No baud_rate specified nor default configured')
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baud_rate = self.baud_rate
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data = None
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try:
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serial_available = self.serial_lock.acquire(timeout=2)
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if serial_available:
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try:
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ser = self._get_serial(device=device, baud_rate=baud_rate)
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except Exception as e:
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self.logger.debug(e)
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time.sleep(1)
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ser = self._get_serial(device=device, baud_rate=baud_rate, reset=True)
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data = self._read_json(ser)
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try:
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data = json.loads(data)
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except (ValueError, TypeError):
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self.logger.warning('Invalid JSON message from {}: {}'.format(self.device, data))
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else:
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data = self.last_measurement
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finally:
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try:
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self.serial_lock.release()
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except Exception as e:
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self.logger.debug(e)
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if data:
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self.last_measurement = data
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return data
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@action
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def read(self, device=None, baud_rate=None, size=None, end=None):
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"""
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Reads raw data from the serial device
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:param device: Device to read (default: default configured device)
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:type device: str
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:param baud_rate: Baud rate (default: default configured baud_rate)
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:type baud_rate: int
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:param size: Number of bytes to read
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:type size: int
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:param end: End of message byte or character
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:type end: int, bytes or str
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"""
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if not device:
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if not self.device:
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raise RuntimeError('No device specified nor default device configured')
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device = self.device
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if baud_rate is None:
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if self.baud_rate is None:
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raise RuntimeError('No baud_rate specified nor default configured')
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baud_rate = self.baud_rate
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if (size is None and end is None) or (size is not None and end is not None):
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raise RuntimeError('Either size or end must be specified')
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if end and isinstance(end, str) and len(end) > 1:
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raise RuntimeError('The serial end must be a single character, not a string')
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data = bytes()
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try:
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serial_available = self.serial_lock.acquire(timeout=2)
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if serial_available:
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try:
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ser = self._get_serial(device=device, baud_rate=baud_rate)
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except Exception as e:
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self.logger.debug(e)
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time.sleep(1)
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ser = self._get_serial(device=device, baud_rate=baud_rate, reset=True)
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if size is not None:
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for _ in range(0, size):
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data += ser.read()
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elif end is not None:
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if isinstance(end, str):
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end = end.encode()
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ch = None
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while ch != end:
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ch = ser.read()
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if ch != end:
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data += ch
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else:
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self.logger.warning('Serial read timeout')
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finally:
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try:
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self.serial_lock.release()
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except Exception as e:
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self.logger.debug(e)
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try:
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data = data.decode()
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except (ValueError, TypeError):
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data = base64.encodebytes(data)
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return data
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@action
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def write(self, data, device=None, baud_rate=None):
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"""
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Writes data to the serial device.
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:param device: Device to write (default: default configured device)
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:type device: str
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:param baud_rate: Baud rate (default: default configured baud_rate)
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:type baud_rate: int
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:param data: Data to send to the serial device
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:type data: str, bytes or dict. If dict, it will be serialized as JSON.
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"""
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if not device:
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if not self.device:
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raise RuntimeError('No device specified nor default device configured')
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device = self.device
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if baud_rate is None:
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if self.baud_rate is None:
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raise RuntimeError('No baud_rate specified nor default configured')
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baud_rate = self.baud_rate
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if isinstance(data, dict):
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data = json.dumps(data)
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if isinstance(data, str):
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data = data.encode('utf-8')
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try:
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serial_available = self.serial_lock.acquire(timeout=2)
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if serial_available:
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try:
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ser = self._get_serial(device=device, baud_rate=baud_rate)
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except Exception as e:
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self.logger.debug(e)
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time.sleep(1)
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ser = self._get_serial(device=device, baud_rate=baud_rate, reset=True)
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self.logger.info('Writing {} to {}'.format(data, self.device))
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ser.write(data)
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finally:
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try:
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self.serial_lock.release()
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except Exception as e:
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self.logger.debug(e)
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# vim:sw=4:ts=4:et:
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