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1 | ## | |
2 | ## This file is part of the sigrok project. | |
3 | ## | |
4 | ## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de> | |
5 | ## | |
6 | ## This program is free software; you can redistribute it and/or modify | |
7 | ## it under the terms of the GNU General Public License as published by | |
8 | ## the Free Software Foundation; either version 2 of the License, or | |
9 | ## (at your option) any later version. | |
10 | ## | |
11 | ## This program is distributed in the hope that it will be useful, | |
12 | ## but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | ## GNU General Public License for more details. | |
15 | ## | |
16 | ## You should have received a copy of the GNU General Public License | |
17 | ## along with this program; if not, write to the Free Software | |
18 | ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
19 | ## | |
20 | ||
21 | ''' | |
22 | 1-Wire protocol decoder. | |
23 | ||
24 | The 1-Wire protocol enables bidirectional communication over a single wire (and | |
25 | ground) between a single master and one or multiple slaves. The protocol is | |
26 | layered, the provided parser decodes the next layers: | |
27 | - Link layer (reset, presence detection, reading/writing bits) | |
28 | - Network layer (skip, search, match device ROM addresses) | |
29 | The higher layers (transport, presentation) are not decoded, since they are | |
30 | mostly device specific and it would take a lot of code to interpret them. | |
31 | ||
32 | Sample rate: | |
33 | A high enough sample rate is required to properly detect all the elements of | |
34 | the protocol. A lower sample rate can be used if the master does not use | |
35 | overdrive communication speed. The next minimal values should be used: | |
36 | - overdrive available: 2MHz minimum, 5MHz suggested | |
37 | - overdrive not available: 400kHz minimum, 1MHz suggested | |
38 | ||
39 | Probes: | |
40 | 1-Wire requires a single signal, but some master implementations might have a | |
41 | separate signal use to deliver power to the bus during temperature conversion | |
42 | as an example. This power signal is currently not parsed. | |
43 | - owr (1-Wire bus) | |
44 | - pwr (1-Wire power) | |
45 | ||
46 | Options: | |
47 | 1-Wire is an asynchronous protocol, so the decoder must know the sample rate. | |
48 | The timing for sampling bits, presence and reset is calculated by the decoder, | |
49 | but in case the user wishes to use different values, it is possible to | |
50 | configure the next timing values (number of sample rate periods): | |
51 | - overdrive (if active the decoder will be prepared for overdrive) | |
52 | - cnt_normal_bit (time for normal mode sample bit) | |
53 | - cnt_normal_presence (time for normal mode sample presence) | |
54 | - cnt_normal_reset (time for normal mode reset) | |
55 | - cnt_overdrive_bit (time for overdrive mode sample bit) | |
56 | - cnt_overdrive_presence (time for overdrive mode sample presence) | |
57 | - cnt_overdrive_reset (time for overdrive mode reset) | |
58 | This options should be configured only on very rare cases and the user should | |
59 | read the decoder source code to understand them correctly. | |
60 | ||
61 | Annotations: | |
62 | Annotations can be shown for each layer of the protocol separately: | |
63 | - link (the value of each transmitted bit is shown separately) | |
64 | - network (the ROM command, and address are shown) | |
65 | - transport (only transport layer byte transfers are shown) | |
66 | If link layer annotations are shown, possible issues with sample rate and sample | |
67 | timing are also shown. | |
68 | ||
69 | TODO: | |
70 | - add CRC checks for network layer | |
71 | - add transport layer code | |
72 | - review link layer code, to check for protocol correctness | |
73 | - define output protocol | |
74 | ''' | |
75 | ||
76 | from .onewire import * | |
77 |