async def _try_open_port(port) -> (bool, AioSerial):
"""
Try to connect to the given port.
:param port: The port to connect to
:return: (success value, connection)
"""
new_connection = AioSerial()
new_connection.port = port.device
i = 0
while not new_connection.is_open and i < 5: # Make multiple attempts in case device is busy
i += 1
try:
new_connection.open()
except SerialException as e:
await sleep(1)
if not new_connection.is_open: # Failed to connect
return False, None
return True, new_connection
class SerialConnection:
def __init__(self,
port=None,
baudrate=9600,
timeout=1,
inter_byte_delay=None):
self.ser = AioSerial(port, baudrate, timeout=timeout)
self.inter_byte_delay = inter_byte_delay
def open(self):
"""
Open serial port connection
"""
if not self.ser.is_open:
self.ser.open()
def readline(self):
"""
Read line from serial port
:return: One line from serial stream
"""
try:
output = self.ser.readline()
return output
except SerialException as se:
log.error('Serial connection read error: {}'.format(se))
return None
async def readline_async(self):
"""
Asynchronously read line from serial port
:return: One line from serial stream
"""
try:
output = await self.ser.readline_async()
return output
except asyncio.CancelledError:
log.error(f'readline_async() future cancelled')
return None
def write(self, data):
"""
Write data to serial port
:param data: Data to send
"""
try:
if self.inter_byte_delay:
for byte in data:
self.ser.write(bytes([byte]))
sleep(self.inter_byte_delay)
else:
self.ser.write(data)
except SerialException as se:
log.error('Serial connection write error: {}'.format(se))
async def write_async(self, data):
"""
Asynchronously write data to serial port
:param data: Data to send
"""
try:
if self.inter_byte_delay:
for byte in data:
await self.ser.write_async(bytes([byte]))
await asyncio.sleep(self.inter_byte_delay)
else:
await self.ser.write_async(data)
except asyncio.CancelledError:
log.error(f'write_async() future cancelled')
def send_break(self, duration=0.25):
"""
Send break condition to serial port
:param duration: Break duration
"""
try:
self.ser.send_break(duration)
except SerialException as se:
log.error('Serial connection send break error: {}'.format(se))
def close(self):
"""
Close serial port connection
"""
self.ser.close()