| Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 1 | Kernel driver lm70 |
| 2 | ================== |
| 3 | |
| Manuel Lauss | c8ac32e | 2009-01-07 16:37:34 +0100 | [diff] [blame] | 4 | Supported chips: |
| Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 5 | * National Semiconductor LM70 |
| 6 | Datasheet: http://www.national.com/pf/LM/LM70.html |
| Manuel Lauss | c8ac32e | 2009-01-07 16:37:34 +0100 | [diff] [blame] | 7 | * Texas Instruments TMP121/TMP123 |
| 8 | Information: http://focus.ti.com/docs/prod/folders/print/tmp121.html |
| Christophe Leroy | a86e94d | 2012-09-05 11:49:14 +0200 | [diff] [blame] | 9 | * National Semiconductor LM71 |
| 10 | Datasheet: http://www.ti.com/product/LM71 |
| 11 | * National Semiconductor LM74 |
| 12 | Datasheet: http://www.ti.com/product/LM74 |
| Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 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 | |
| Kaiwan N Billimoria | 2b73005 | 2009-01-07 16:37:34 +0100 | [diff] [blame] | 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 | |
| Christophe Leroy | a86e94d | 2012-09-05 11:49:14 +0200 | [diff] [blame] | 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). |
| Manuel Lauss | c8ac32e | 2009-01-07 16:37:34 +0100 | [diff] [blame] | 43 | |
| Kaiwan N Billimoria | e1a8e91 | 2006-06-12 22:00:05 +0200 | [diff] [blame] | 44 | Thanks to |
| 45 | --------- |
| 46 | Jean Delvare <khali@linux-fr.org> for mentoring the hwmon-side driver |
| 47 | development. |