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51990c45 | 1 | ## |
50bd5d25 | 2 | ## This file is part of the libsigrokdecode project. |
51990c45 IJ |
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 | |
4539e9ca | 17 | ## along with this program; if not, see <http://www.gnu.org/licenses/>. |
51990c45 IJ |
18 | ## |
19 | ||
20 | ''' | |
4c3b1846 | 21 | This protocol decoder handles the 1-Wire link layer. |
51990c45 | 22 | |
e7720d6c UH |
23 | The 1-Wire protocol enables bidirectional communication over a single wire |
24 | (and ground) between a single master and one or multiple slaves. The protocol | |
25 | is layered: | |
4633e258 | 26 | |
e7720d6c UH |
27 | - Link layer (reset, presence detection, reading/writing bits) |
28 | - Network layer (skip/search/match device ROM addresses) | |
29 | - Transport layer (transport data between 1-Wire master and device) | |
30 | ||
f4d0363d | 31 | Sample rate: |
e7720d6c UH |
32 | A sufficiently high samplerate is required to properly detect all the elements |
33 | of the protocol. A lower samplerate can be used if the master does not use | |
34 | overdrive communication speed. The following minimal values should be used: | |
35 | ||
36 | - overdrive available: 2MHz minimum, 5MHz suggested | |
37 | - overdrive not available: 400kHz minimum, 1MHz suggested | |
f4d0363d | 38 | |
6a15597a | 39 | Channels: |
a2b13347 | 40 | 1-Wire requires a single signal, but some master implementations might have a |
e7720d6c UH |
41 | separate signal used to deliver power to the bus during temperature conversion |
42 | as an example. This power signal is currently not used. | |
43 | ||
44 | - owr (1-Wire signal line) | |
45 | - pwr (optional, dedicated power supply pin) | |
a2b13347 IJ |
46 | |
47 | Options: | |
e7720d6c UH |
48 | 1-Wire is an asynchronous protocol, so the decoder must know the samplerate. |
49 | The timing for sampling bits, presence, and reset is calculated by the decoder, | |
a2b13347 | 50 | but in case the user wishes to use different values, it is possible to |
e7720d6c UH |
51 | configure the following timing values (number of samplerate periods): |
52 | ||
53 | - overdrive (if active the decoder will be prepared for overdrive) | |
54 | - cnt_normal_bit (time for normal mode sample bit) | |
55 | - cnt_normal_slot (time for normal mode data slot) | |
56 | - cnt_normal_presence (time for normal mode sample presence) | |
57 | - cnt_normal_reset (time for normal mode reset) | |
58 | - cnt_overdrive_bit (time for overdrive mode sample bit) | |
59 | - cnt_overdrive_slot (time for overdrive mode data slot) | |
60 | - cnt_overdrive_presence (time for overdrive mode sample presence) | |
61 | - cnt_overdrive_reset (time for overdrive mode reset) | |
62 | ||
63 | These options should be configured only on very rare cases and the user should | |
a2b13347 | 64 | read the decoder source code to understand them correctly. |
51990c45 IJ |
65 | ''' |
66 | ||
95d11271 | 67 | from .pd import Decoder |