Hi All,
After all the fuss I created learning lm_sensors I'm really pleased
to provide this example, 'cos last couple months I didn't think it
could be described in sensors.conf :o)
ADM9240 and negative voltage measurement
`````````````````````````````````````````
Negative voltage readings are an offset positive value created by
use of a resistor divider from 5V to Vminus:
# -------o----------------o------> + 5V
# | |
# - |
# | | R1 ---------------
# | | | Vref
# - |
# | Vread |
# o-----------| Vccp1
# | |
# - | ADM9240
# | | R2 |
# | | ---------------
# -
# |
# -------0---> Vminus
The ADM9240 does not provide a reference voltage to drive the top
of the resistor divider, so the 'compute' line for negative voltages
needs to reference the 5V reading in order to correct for drift in
+5V supply. I have a preference for traceable transforms, thus the
compute lines detail the transform rather than simplify the math
required for a valid transform (besides, I've forgotten most of my
math :) Resistor ratio discovery is detailed in prior posts.
# /etc/sensors.conf
#
# For Intel SE440BX-2 with ADM9240 by Grant Coady 2005-05-13
chip "adm9240-*" "ds1780-*" "lm81-*"
label "2.5V" " 1.5V"
label "3.3V" " 3.3V"
label "5V" " 5V"
label "12V" " 12V"
label "Vccp1" " -5V"
label "Vccp2" " -12V"
label fan1 "PSU Fan"
ignore fan2
label temp "Ambient"
# + internally scaled
compute "2.5V" @, @
compute "3.3V" @, @
compute "5V" @, @
compute "12V" @, @
# -5V
compute "Vccp1" "5V"+((@-"5V")*(1+(27/12))), "5V"-(("5V"-@)/(1+(27/12)))
# -12V
compute "Vccp2" "5V"+((@-"5V")*(1+(82/15))), "5V"-(("5V"-@)/(1+(82/15)))
set "2.5V_min" 1.5 * 0.91
set "2.5V_max" 1.5 * 1.09
set "3.3V_min" 3.3 * 0.95
set "3.3V_max" 3.3 * 1.05
set "5V_min" 5 * 0.95
set "5V_max" 5 * 1.05
set "12V_min" 12 * 0.95
set "12V_max" 12 * 1.05
set "Vccp1_max" -5 * 0.90
set "Vccp1_min" -5 * 1.10
set "Vccp2_max" -12 * 0.90
set "Vccp2_min" -12 * 1.10
# set fan1_div 8 # auto fan_div, throws error on write attempt
set fan1_min 1200
# set fan2_min 1234
set temp_over 50
set temp_hyst 45
# end ADM9240
peetoo:~$ uname -a
Linux peetoo 2.6.11.9a #2 Thu May 12 14:20:41 EST 2005 i686 unknown unknown GNU/Linux
peetoo:~$ sensors
adm9240-i2c-0-2d
Adapter: SMBus PIIX4 adapter at 7000
1.5V: +1.51 V (min = +1.37 V, max = +1.64 V)
-5V: -5.08 V (min = -5.49 V, max = -4.48 V)
3.3V: +3.35 V (min = +3.13 V, max = +3.47 V)
5V: +5.18 V (min = +4.74 V, max = +5.26 V)
12V: +12.31 V (min = +11.38 V, max = +12.62 V)
-12V: -11.59 V (min = -13.24 V, max = -10.78 V)
PSU Fan: 1493 RPM (min = 1205 RPM, div = 8)
Ambient: +33.5?C (high = +50?C, hyst = +45?C)
alarms:
Me happy, thank you very much to those patient people here who
helped me understand lm_sensors, drivers, and completing the
port of adm9240 to 2.6. My first l-k project.
Patches for adm9240 driver suit 2.6.11.8, 2.6.11.9 are available
from http://scatter.mine.nu/hwmon/adm9240/ plus some documentation.
--Grant.
