1 .. SPDX-License-Identifier: GPL-2.0-or-later
2
3 =====================
4 Kernel driver w1-uart
5 =====================
6
7 Author: Christoph Winklhofer <cj.winklhofer@gma
8
9
10 Description
11 -----------
12
13 UART 1-Wire bus driver. The driver utilizes th
14 Serial Device Bus to create the 1-Wire timing
15 the document `"Using a UART to Implement a 1-W
16
17 .. _"Using a UART to Implement a 1-Wire Bus Ma
18
19 In short, the UART peripheral must support ful
20 open-drain mode. The timing patterns are gener
21 combination of baud-rate and transmitted byte,
22 1-Wire read bit, write bit or reset pulse.
23
24 For instance the timing pattern for a 1-Wire r
25 the baud-rate 9600, i.e. 104.2 us per bit. The
26 UART (least significant bit first, start-bit l
27 for 1-Wire to 521 us. A present 1-Wire device
28 pulling the line low, which is used by the dri
29 the 1-Wire operation.
30
31 Similar for a 1-Wire read bit or write bit, wh
32 115200, i.e. 8.7 us per bit. The transmitted b
33 Write-0 operation (low time 69.6us) and the by
34 and Write-1 (low time 8.7us).
35
36 The default baud-rate for reset and presence d
37 a 1-Wire read or write operation 115200. In ca
38 is different from the requested one, the trans
39 to generate the 1-Wire timing patterns.
40
41
42 Usage
43 -----
44
45 Specify the UART 1-wire bus in the device tree
46 onewire to the serial node (e.g. uart0). For e
47 ::
48
49 @uart0 {
50 ...
51 onewire {
52 compatible = "w1-uart";
53 };
54 };
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