X-Git-Url: https://sigrok.org/gitweb/?p=libsigrokdecode.git;a=blobdiff_plain;f=decoders%2Fonewire_transport%2F__init__.py;fp=decoders%2Fonewire_transport%2F__init__.py;h=28db017107c5f92891868f6493f233df18e5e319;hp=0000000000000000000000000000000000000000;hb=a81787f62362e7ab8471c4c01baa6a806d624d58;hpb=671cc3009b967bd105757d0a0c267a68f18c58b9

diff --git a/decoders/onewire_transport/__init__.py b/decoders/onewire_transport/__init__.py
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+##
+## This file is part of the sigrok project.
+##
+## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+##
+
+'''
+1-Wire protocol decoder.
+
+The 1-Wire protocol enables bidirectional communication over a single wire (and
+ground) between a single master and one or multiple slaves. The protocol is
+layered, the provided parser decodes the next layers:
+- Link layer (reset, presence detection, reading/writing bits)
+- Network layer (skip, search, match device ROM addresses)
+The higher layers (transport, presentation) are not decoded, since they are
+mostly device specific and it would take a lot of code to interpret them.
+
+Sample rate:
+A high enough sample rate is required to properly detect all the elements of
+the protocol. A lower sample rate can be used if the master does not use
+overdrive communication speed. The next minimal values should be used:
+- overdrive     available:   2MHz minimum, 5MHz suggested
+- overdrive not available: 400kHz minimum, 1MHz suggested
+
+Probes:
+1-Wire requires a single signal, but some master implementations might have a
+separate signal use to deliver power to the bus during temperature conversion
+as an example. This power signal is currently not parsed.
+- owr (1-Wire bus)
+- pwr (1-Wire power)
+
+Options:
+1-Wire is an asynchronous protocol, so the decoder must know the sample rate.
+The timing for sampling bits, presence and reset is calculated by the decoder,
+but in case the user wishes to use different values, it is possible to
+configure the next timing values (number of sample rate periods):
+- overdrive              (if active the decoder will be prepared for overdrive)
+- cnt_normal_bit         (time for normal mode sample bit)
+- cnt_normal_presence    (time for normal mode sample presence)
+- cnt_normal_reset       (time for normal mode reset)
+- cnt_overdrive_bit      (time for overdrive mode sample bit)
+- cnt_overdrive_presence (time for overdrive mode sample presence)
+- cnt_overdrive_reset    (time for overdrive mode reset)
+This options should be configured only on very rare cases and the user should
+read the decoder source code to understand them correctly.
+
+Annotations:
+Annotations can be shown for each layer of the protocol separately:
+- link (the value of each transmitted bit is shown separately)
+- network (the ROM command, and address are shown)
+- transport (only transport layer byte transfers are shown)
+If link layer annotations are shown, possible issues with sample rate and sample
+timing are also shown.
+
+TODO:
+- add CRC checks for network layer
+- add transport layer code
+- review link layer code, to check for protocol correctness
+- define output protocol
+'''
+
+from .onewire_transport import *