src/test_driver/mbed/integration_tests/common/serial_connection.py

# Copyright (c) 2009-2021 Arm Limited
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import logging
from time import sleep

from serial import Serial, SerialException

log = logging.getLogger(__name__)


class SerialConnection:
    """
    Serial Connection class containing serial connection handling functions
    :param port: serial port name
    :param baudrate: serial baudrate
    :param timeout: serial read timeout in seconds (float)
    :param inter_byte_delay: time in second between two bytes sent on the serial line (float)
    """

    def __init__(self, port=None, baudrate=9600, timeout=1, inter_byte_delay=None):
        self.ser = Serial(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 read(self, size=1):
        """
        Read bytes from serial port
        :return: Bytes from serial stream
        """
        if not self.ser.is_open:
            return None
        try:
            output = self.ser.read(size)
            return output
        except SerialException as se:
            log.error('Serial connection read error: {}'.format(se))
            return None

    def readline(self):
        """
        Read line from serial port
        :return: One line from serial stream
        """
        if not self.ser.is_open:
            return None
        try:
            output = self.ser.readline()
            return output
        except SerialException as se:
            log.error('Serial connection read line error: {}'.format(se))
            return None

    def write(self, data):
        """
        Write data to serial port
        :param data: Data to send
        """
        if not self.ser.is_open:
            return
        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))

    def send_break(self, duration=0.25):
        """
        Send break condition to serial port
        :param duration: Break duration
        """
        if not self.ser.is_open:
            return None
        try:
            self.ser.send_break(duration)
        except SerialException as se:
            log.error('Serial connection send break error: {}'.format(se))

    def get_timeout(self):
        """
        Get read timeout of serial port
        :return: Read timeout value in seconds
        """
        try:
            timeout = self.ser.timeout
        except SerialException as se:
            log.error('Serial connection get read timeout error: {}'.format(se))

        return timeout

    def set_timeout(self, timeout=1):
        """
        Set read timeout of serial port
        :param timeout: timeout value in seconds
        """
        try:
            self.ser.timeout = timeout
        except SerialException as se:
            log.error('Serial connection set read timeout error: {}'.format(se))

    def close(self):
        """
        Close serial port connection
        """
        log.info('Close serial port')
        self.ser.close()