From 86d44b5869c6ba7ecefdd4a48176566e62d39eab Mon Sep 17 00:00:00 2001 From: "Mark D. Studebaker" Date: Wed, 31 Oct 2001 02:53:28 +0000 Subject: [PATCH] fix it87 in5,in6 calculations in sensors.conf.eg git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@1213 7894878c-1315-0410-8ee3-d5d059ff63e0 --- CHANGES | 1 + etc/sensors.conf.eg | 18 +++++++++++++----- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/CHANGES b/CHANGES index b6b43038..f7b3ab38 100644 --- a/CHANGES +++ b/CHANGES @@ -21,6 +21,7 @@ ask CVS about it: Chip Modules (all): malloc.h -> slab.h Modules (all): Add MODULE_LICENSE("GPL") File doc/FAQ: More updates and additions + File sensors.conf.eg: Fix it87 in5,in6 (-12,-5) calculations Module fscpos: new (Fujitsu-Siemens Poseidon driver) Module i2c-amd756: Improve busy handling/printk's Module i2c-i801: Add 82801CA/CAM support diff --git a/etc/sensors.conf.eg b/etc/sensors.conf.eg index f6196024..6e35a4a6 100644 --- a/etc/sensors.conf.eg +++ b/etc/sensors.conf.eg @@ -1031,17 +1031,25 @@ chip "it87-*" # For this family of chips the negative voltage equation is different from # the lm78. The chip uses two external resistor for scaling but one is -# tied to a positive reference voltage. See ITE8705F datasheet (SIS950 +# tied to a positive reference voltage. See ITE8705/12 datasheet (SIS950 # data sheet is wrong) # Vs = (1 + Rin/Rf) * Vin - (Rin/Rf) * Vref. # Vref = 4.096 volts, Vin is voltage measured, Vs is actual voltage. - compute in2 (1 + 1)*@ , @/(1 + 1) compute in3 ((6.8/10)+1)*@ , @/((6.8/10)+1) compute in4 ((30/10) +1)*@ , @/((30/10) +1) -# Since these have the wrong equation form they are probably not correct - compute in5 -(72/10)*@ , -@/(72/10) - compute in6 -(56/10)*@ , -@/(56/10) +# The next two are negative voltages (-12 and -5). +# The following formulas must be used. Unfortunately the datasheet +# does not give recommendations for Rin, Rf, but we can back into +# them based on a nominal +2V input to the chip, together with a 4.096V Vref. +# Formula: +# actual V = (Vmeasured * (1 + Rin/Rf)) - (Vref * (Rin/Rf)) +# For -12V input use Rin/Rf = 6.68 +# For -5V input use Rin/Rf = 3.33 +# Then you can convert the forumula to a standard form like: + compute in5 (7.67 * @) - 27.36 , (@ + 27.36) / 7.67 + compute in6 (4.33 * @) - 13.64 , (@ + 13.64) / 4.33 +# compute in7 ((6.8/10)+1)*@ , @/((6.8/10)+1) # Temperature