lm83.rst 3.7 KB

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  1. Kernel driver lm83
  2. ==================
  3. Supported chips:
  4. * National Semiconductor LM83
  5. Prefix: 'lm83'
  6. Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  7. Datasheet: Publicly available at the National Semiconductor website
  8. http://www.national.com/pf/LM/LM83.html
  9. * National Semiconductor LM82
  10. Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
  11. Datasheet: Publicly available at the National Semiconductor website
  12. http://www.national.com/pf/LM/LM82.html
  13. Author: Jean Delvare <jdelvare@suse.de>
  14. Description
  15. -----------
  16. The LM83 is a digital temperature sensor. It senses its own temperature as
  17. well as the temperature of up to three external diodes. The LM82 is
  18. a stripped down version of the LM83 that only supports one external diode.
  19. Both are compatible with many other devices such as the LM84 and all
  20. other ADM1021 clones. The main difference between the LM83 and the LM84
  21. in that the later can only sense the temperature of one external diode.
  22. Using the adm1021 driver for a LM83 should work, but only two temperatures
  23. will be reported instead of four.
  24. The LM83 is only found on a handful of motherboards. Both a confirmed
  25. list and an unconfirmed list follow. If you can confirm or infirm the
  26. fact that any of these motherboards do actually have an LM83, please
  27. contact us. Note that the LM90 can easily be misdetected as a LM83.
  28. Confirmed motherboards:
  29. === =====
  30. SBS P014
  31. SBS PSL09
  32. === =====
  33. Unconfirmed motherboards:
  34. =========== ==========
  35. Gigabyte GA-8IK1100
  36. Iwill MPX2
  37. Soltek SL-75DRV5
  38. =========== ==========
  39. The LM82 is confirmed to have been found on most AMD Geode reference
  40. designs and test platforms.
  41. The driver has been successfully tested by Magnus Forsström, who I'd
  42. like to thank here. More testers will be of course welcome.
  43. The fact that the LM83 is only scarcely used can be easily explained.
  44. Most motherboards come with more than just temperature sensors for
  45. health monitoring. They also have voltage and fan rotation speed
  46. sensors. This means that temperature-only chips are usually used as
  47. secondary chips coupled with another chip such as an IT8705F or similar
  48. chip, which provides more features. Since systems usually need three
  49. temperature sensors (motherboard, processor, power supply) and primary
  50. chips provide some temperature sensors, the secondary chip, if needed,
  51. won't have to handle more than two temperatures. Thus, ADM1021 clones
  52. are sufficient, and there is no need for a four temperatures sensor
  53. chip such as the LM83. The only case where using an LM83 would make
  54. sense is on SMP systems, such as the above-mentioned Iwill MPX2,
  55. because you want an additional temperature sensor for each additional
  56. CPU.
  57. On the SBS P014, this is different, since the LM83 is the only hardware
  58. monitoring chipset. One temperature sensor is used for the motherboard
  59. (actually measuring the LM83's own temperature), one is used for the
  60. CPU. The two other sensors must be used to measure the temperature of
  61. two other points of the motherboard. We suspect these points to be the
  62. north and south bridges, but this couldn't be confirmed.
  63. All temperature values are given in degrees Celsius. Local temperature
  64. is given within a range of 0 to +85 degrees. Remote temperatures are
  65. given within a range of 0 to +125 degrees. Resolution is 1.0 degree,
  66. accuracy is guaranteed to 3.0 degrees (see the datasheet for more
  67. details).
  68. Each sensor has its own high limit, but the critical limit is common to
  69. all four sensors. There is no hysteresis mechanism as found on most
  70. recent temperature sensors.
  71. The lm83 driver will not update its values more frequently than every
  72. other second; reading them more often will do no harm, but will return
  73. 'old' values.