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1 | Kernel driver lm70 |
2 | ================== | |
3 | ||
c8ac32e4 | 4 | Supported chips: |
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5 | * National Semiconductor LM70 |
6 | Datasheet: http://www.national.com/pf/LM/LM70.html | |
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7 | * Texas Instruments TMP121/TMP123 |
8 | Information: http://focus.ti.com/docs/prod/folders/print/tmp121.html | |
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9 | * National Semiconductor LM71 |
10 | Datasheet: http://www.ti.com/product/LM71 | |
11 | * National Semiconductor LM74 | |
12 | Datasheet: http://www.ti.com/product/LM74 | |
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13 | |
14 | Author: | |
15 | Kaiwan N Billimoria <kaiwan@designergraphix.com> | |
16 | ||
17 | Description | |
18 | ----------- | |
19 | ||
20 | This driver implements support for the National Semiconductor LM70 | |
21 | temperature sensor. | |
22 | ||
23 | The LM70 temperature sensor chip supports a single temperature sensor. | |
24 | It communicates with a host processor (or microcontroller) via an | |
25 | SPI/Microwire Bus interface. | |
26 | ||
27 | Communication with the LM70 is simple: when the temperature is to be sensed, | |
28 | the driver accesses the LM70 using SPI communication: 16 SCLK cycles | |
29 | comprise the MOSI/MISO loop. At the end of the transfer, the 11-bit 2's | |
30 | complement digital temperature (sent via the SIO line), is available in the | |
31 | driver for interpretation. This driver makes use of the kernel's in-core | |
32 | SPI support. | |
33 | ||
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34 | As a real (in-tree) example of this "SPI protocol driver" interfacing |
35 | with a "SPI master controller driver", see drivers/spi/spi_lm70llp.c | |
36 | and its associated documentation. | |
37 | ||
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38 | The LM74 and TMP121/TMP123 are very similar; main difference is 13-bit |
39 | temperature data (0.0625 degrees celsius resolution). | |
40 | ||
41 | The LM71 is also very similar; main difference is 14-bit temperature | |
42 | data (0.03125 degrees celsius resolution). | |
c8ac32e4 | 43 | |
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44 | Thanks to |
45 | --------- | |
7c81c60f | 46 | Jean Delvare <jdelvare@suse.de> for mentoring the hwmon-side driver |
e1a8e913 | 47 | development. |