shellmatta/python_driver/shellmatta_transport_serial.py

""" Wrapper around a shellmatta with transport layer to send commands and receive the response """

import time
import serial
import argparse
from shellmatta_transport import ShellmattaTransport

class ShellmattaSerial():
    """ Helper class to communicate with a shellmatta enabled device """


    def __init__(self, com_port, baudrate=115200, prompt="->", timeout=1, transport_layer_mandatory=False):
        """ Create the transport layer instance using the passed com port """
        self.prompt = prompt
        self.com = com_port
        self.com_port = serial.Serial(com_port, baudrate=baudrate, timeout=timeout)

        self.transport = ShellmattaTransport(self.com_port, transport_layer_mandatory)

    def send_command(self, command, enter=True):
        """ Send command and wait for the prompt in the response. """

        if isinstance(command, str):
            send_data = str.encode(command)
        else:
            send_data = command

        retries = 3

        while retries:
            if enter:
                send_data += b"\r"
            self.transport.write(send_data)
            data = b''

            while True:
                data += self.transport.read()

                if data.endswith(str.encode(self.prompt)):
                    # return received string without echo and prompt
                    data = data[:-len(str.encode(self.prompt))]
                    if data.startswith(send_data):

                        data = data[len(send_data):]

                    break

            # todo implement proper retries / sequence checking
            if b"crc error\r\n" not in data:
                break

            retries -= 1

        return data

    def send_command_only(self, command):
        """ Send command without waiting for response. """

        send_string = command + "\r"
        self.transport.write(str.encode(send_string))

    def send_raw(self, data):
        """ Send a passed bytes string without any mercy. """

        self.transport.write_manual(data)

    def reset_communication(self):
        """ Clears all internal buffers, throwing away all data. """
        self.transport.reset()
        self.com_port.flush()

        self.com_port.reset_input_buffer()
        self.com_port.reset_output_buffer()

        # send cancel - and read response from input buffer
        _result = self.send_command("\x03", enter=False)

    def close_serial(self):
        """ Closes the serial port """
        self.com_port.close()

    def set_baudrate(self, baud):
        """ Set the baudrate of the serial port """
        self.com_port.baudrate = baud
        self.com_port.close()
        time.sleep(0.5)

        self.com_port = serial.Serial(self.com, baudrate=baud, timeout=self.com_port.timeout)
        self.transport.close()
        self.transport = ShellmattaTransport(self.com_port,
                                             False,
                                             None)

# start interactive mode if not used as a module
if __name__ == "__main__":

    # setup an argument parser
    parser = argparse.ArgumentParser()
    parser.add_argument("-c", "--com-port", dest="com_port", help="Com port to use.", required=True)
    parser.add_argument("-b", "--baudrate", dest="baudrate", help="Baudrate to use.", type=int, default=115200)
    parser.add_argument("-p", "--prompt",   dest="prompt",   help="Prompt text of the shellmatta instance.", default="->")
    parser.add_argument("-t", "--timeout",  dest="timeout",  help="Timeout on the com port.", type=float, default=0.1)
    parser.add_argument("-m", "--mandatory", dest="mandatory", help="Force transport layer usage.", default=True)
    args = parser.parse_args()

    # get our own shellmatta serial instance
    shellmatta = ShellmattaSerial(args.com_port,
                                  args.baudrate,
                                  args.prompt,
                                  args.timeout,
                                  args.mandatory)

    shellmatta.reset_communication()

    # process user input
    print("Shellmatta Transport Serial wrapper - type commands as you like:")
    while True:
        command = input()
        print(shellmatta.send_command(command))