| # Copyright 2013-2015 ARM Limited |
| # |
| # 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 time |
| from contextlib import contextmanager |
| from logging import Logger |
| |
| import serial |
| |
| import pexpect |
| from distutils.version import StrictVersion as V |
| if V(pexpect.__version__) < V('4.0.0'): |
| import fdpexpect |
| else: |
| from pexpect import fdpexpect |
| # Adding pexpect exceptions into this module's namespace |
| from pexpect import EOF, TIMEOUT # NOQA pylint: disable=W0611 |
| |
| from devlib.exception import HostError |
| |
| |
| def pulse_dtr(conn, state=True, duration=0.1): |
| """Set the DTR line of the specified serial connection to the specified state |
| for the specified duration (note: the initial state of the line is *not* checked.""" |
| conn.setDTR(state) |
| time.sleep(duration) |
| conn.setDTR(not state) |
| |
| |
| def get_connection(timeout, init_dtr=None, logcls=Logger, |
| *args, **kwargs): |
| if init_dtr is not None: |
| kwargs['dsrdtr'] = True |
| try: |
| conn = serial.Serial(*args, **kwargs) |
| except serial.SerialException as e: |
| raise HostError(e.message) |
| if init_dtr is not None: |
| conn.setDTR(init_dtr) |
| conn.nonblocking() |
| conn.flushOutput() |
| target = fdpexpect.fdspawn(conn.fileno(), timeout=timeout) |
| target.logfile_read = logcls('read') |
| target.logfile_send = logcls('send') |
| |
| # Monkey-patching sendline to introduce a short delay after |
| # chacters are sent to the serial. If two sendline s are issued |
| # one after another the second one might start putting characters |
| # into the serial device before the first one has finished, causing |
| # corruption. The delay prevents that. |
| tsln = target.sendline |
| |
| def sendline(x): |
| tsln(x) |
| time.sleep(0.1) |
| |
| target.sendline = sendline |
| return target, conn |
| |
| |
| def write_characters(conn, line, delay=0.05): |
| """Write a single line out to serial charcter-by-character. This will ensure that nothing will |
| be dropped for longer lines.""" |
| line = line.rstrip('\r\n') |
| for c in line: |
| conn.send(c) |
| time.sleep(delay) |
| conn.sendline('') |
| |
| |
| @contextmanager |
| def open_serial_connection(timeout, get_conn=False, init_dtr=None, |
| logcls=Logger, *args, **kwargs): |
| """ |
| Opens a serial connection to a device. |
| |
| :param timeout: timeout for the fdpexpect spawn object. |
| :param conn: ``bool`` that specfies whether the underlying connection |
| object should be yielded as well. |
| :param init_dtr: specifies the initial DTR state stat should be set. |
| |
| All arguments are passed into the __init__ of serial.Serial. See |
| pyserial documentation for details: |
| |
| http://pyserial.sourceforge.net/pyserial_api.html#serial.Serial |
| |
| :returns: a pexpect spawn object connected to the device. |
| See: http://pexpect.sourceforge.net/pexpect.html |
| |
| """ |
| target, conn = get_connection(timeout, init_dtr=init_dtr, |
| logcls=logcls, *args, **kwargs) |
| if get_conn: |
| yield target, conn |
| else: |
| yield target |
| |
| target.close() # Closes the file descriptor used by the conn. |
| del conn |
| |