Improving Nuvoton NCT6776 lm_sensors output
Monday, November 16. 2015
Problem
My home Linux-box was outputting more-or-less useless lm_sensor output. Example:
coretemp-isa-0000
Adapter: ISA adapter
Physical id 0: +36.0°C (high = +80.0°C, crit = +98.0°C)
Core 0: +34.0°C (high = +80.0°C, crit = +98.0°C)
Core 1: +31.0°C (high = +80.0°C, crit = +98.0°C)
Core 2: +36.0°C (high = +80.0°C, crit = +98.0°C)
Core 3: +33.0°C (high = +80.0°C, crit = +98.0°C)
nct6776-isa-0290
Adapter: ISA adapter
Vcore: +0.97 V (min = +0.00 V, max = +1.74 V)
in1: +1.02 V (min = +0.00 V, max = +0.00 V) ALARM
AVCC: +3.33 V (min = +2.98 V, max = +3.63 V)
+3.3V: +3.31 V (min = +2.98 V, max = +3.63 V)
in4: +1.01 V (min = +0.00 V, max = +0.00 V) ALARM
in5: +2.04 V (min = +0.00 V, max = +0.00 V) ALARM
in6: +0.84 V (min = +0.00 V, max = +0.00 V) ALARM
3VSB: +3.42 V (min = +2.98 V, max = +3.63 V)
Vbat: +3.36 V (min = +2.70 V, max = +3.63 V)
fan1: 0 RPM (min = 0 RPM)
fan2: 703 RPM (min = 0 RPM)
fan3: 0 RPM (min = 0 RPM)
fan4: 819 RPM (min = 0 RPM)
fan5: 0 RPM (min = 0 RPM)
SYSTIN: +36.0°C (high = +0.0°C, hyst = +0.0°C) ALARM sensor = thermistor
CPUTIN: -60.0°C (high = +80.0°C, hyst = +75.0°C) sensor = thermal diode
AUXTIN: +35.0°C (high = +80.0°C, hyst = +75.0°C) sensor = thermistor
PECI Agent 0: +26.0°C (high = +80.0°C, hyst = +75.0°C)
(crit = +88.0°C)
PCH_CHIP_TEMP: +0.0°C
PCH_CPU_TEMP: +0.0°C
PCH_MCH_TEMP: +0.0°C
That's all great and all, but what the heck are in 1, 4-6 and fan 1-5? Are the in 1, 4-6 readings really reliable? Why are there sensors with 0 RPM readings? CPUTIN indicating -60 degrees, really? PCH-temps are all 0, why?
Investigation
In order to get to bottom of all this, let's start from the chip in question. lm_sensors -setup identified it as NCT6776. For some reason Nuvoton doesn't have the data sheet anymore, but by little bit of googling, a PDF with title NCT6776F / NCT6776D Nuvoton LPC I/O popped up.
Analog inputs:
Following information can be found:
It contains following analog inputs:
- AVCC
- VBAT
- 3VSB
- 3VCC
- CPUVCORE
- VIN0
- VIN1
- VIN2
- VIN3
The good thing is, that first 5 of them are clearly labeled, but inputs 0 through 3 are not. They can be pretty much anything.
Revolution Pulse counters:
When it comes to RPM-readings, following information is available:
That lists following inputs:
- SYSFANIN
- CPUFANIN
- AUXFANIN0
- AUXFANIN1
- AUXFANIN2
Looks like all of those have connectors on my motherboard.
Temperature Sources:
For the temperature measurements, the chip has:
The analog temperature inputs are:
- SMIOVT1
- SMIOVT2
- SMIOVT3
- SMIOVT4
- SMIOVT5
- SMIOVT6
According to the above table, they're mapped into AUXTIN, CPUTIN and SYSTIN.
Also on top of those, there is PECI (Platform Environment Control Interface). A definition says "PECI is a new digital interface to read the CPU temperature of Intel® CPUs". So, there aren't any analog pins for that, but there are readings available, when questioned.
Configuration
A peek in to /etc/sensors3.conf at the definition of the chip shows:
chip "w83627ehf-*" "w83627dhg-*" "w83667hg-*" "nct6775-*" "nct6776-*"
label in0 "Vcore"
label in2 "AVCC"
label in3 "+3.3V"
label in7 "3VSB"
label in8 "Vbat"
set in2_min 3.3 * 0.90
set in2_max 3.3 * 1.10
set in3_min 3.3 * 0.90
set in3_max 3.3 * 1.10
set in7_min 3.3 * 0.90
set in7_max 3.3 * 1.10
set in8_min 3.0 * 0.90
set in8_max 3.3 * 1.10
And that's all. I guess that would be ok for the generic case, but in my particular box that list of settings doesn't cover half of the inputs.
Solution
Configuration changes
I added following settings for temperature into "chip "w83627ehf-*" "w83627dhg-*" "w83667hg-*" "nct6775-*" "nct6776-*""-section:
label in0 "Vcore"
set in0_min 1.1 * 0.9
set in0_max 1.1 * 1.15
label in1 "+12V"
compute in1 @ * 12, @ / 12
set in1_min 12 * 0.95
set in1_max 12 * 1.1
label in2 "AVCC"
set in2_min 3.3 * 0.95
set in2_max 3.3 * 1.1
label in3 "+3.3V"
set in3_min 3.3 * 0.95
set in3_max 3.3 * 1.1
label in4 "+5V"
compute in4 @ * 5, @ / 5
set in4_min 5 * 0.95
set in4_max 5 * 1.1
ignore in5
ignore in6
label in7 "3VSB"
set in7_min 3.3 * 0.95
set in7_max 3.3 * 1.1
label in8 "Vbat"
set in8_min 3.3 * 0.95
set in8_max 3.3 * 1.1
The obvious problem still stands: what are the undocumented in 1, 4, 5 and 6? Mr. Ian Dobson at Ubuntuforums.org discussion about NCT6776 claims, that in1 is for +12 VDC power and in4 is for +5VDC power. I cannot deny nor confirm that for my board. The Novoton-chip only provides the inputs, but there is absolutely no way of telling how the manufacturer chooses to connect them to various parts of the MoBo. I took the same assumption, so all that was necessary, was to multiply the input data by 12 and 5 to get a proper reading. I don't know what in5 and in6 are for, that's why I remove them from the display. All the other ones are min and max boundaries for the known readings.
The fan settings are machine specific, in my case:
label fan2 "CPU fan"
set fan2_min 200
label fan4 "HDD fan"
set fan4_min 200
ignore fan1
ignore fan3
ignore fan5
As I only have fans connected to 2 out of 5, I'll ignore the not connected ones. For the connected, I set a lower limit of 200 RPM.
Temperatures are motherboard-specific. In my case, I did following additions:
label temp1 "MB"
set temp1_max 38
set temp1_max_hyst 35
label temp3 "CPU"
label temp7 "CPU?"
ignore temp2
ignore temp8
ignore temp9
ignore temp10
The easy part is to remove the values not displaying anything. The hard part is to try to figure out what the measurements indicate. Based on the other readings, temp3 is CPU combined somehow. The other sensor is displaying rougly same values for each core I have there. However, the temp7 is for PECI, but it doesn't behave anything like CPU-temps. It should, but it doesn't. That's why I left a question mark after it.
Resulting output
After the additions, following output is available:
coretemp-isa-0000
Adapter: ISA adapter
Physical id 0: +48.0°C (high = +80.0°C, crit = +98.0°C)
Core 0: +48.0°C (high = +80.0°C, crit = +98.0°C)
Core 1: +40.0°C (high = +80.0°C, crit = +98.0°C)
Core 2: +43.0°C (high = +80.0°C, crit = +98.0°C)
Core 3: +39.0°C (high = +80.0°C, crit = +98.0°C)
nct6776-isa-0290
Adapter: ISA adapter
Vcore: +1.22 V (min = +0.99 V, max = +1.26 V)
+12V: +12.29 V (min = +11.42 V, max = +13.25 V)
AVCC: +3.33 V (min = +3.14 V, max = +3.63 V)
+3.3V: +3.31 V (min = +3.14 V, max = +3.63 V)
+5V: +5.04 V (min = +4.76 V, max = +5.52 V)
3VSB: +3.42 V (min = +3.14 V, max = +3.63 V)
Vbat: +3.38 V (min = +3.14 V, max = +3.63 V)
CPU fan: 912 RPM (min = 200 RPM)
HDD fan: 897 RPM (min = 200 RPM)
MB: +35.0°C (high = +38.0°C, hyst = +35.0°C) sensor = thermistor
CPU: +37.0°C (high = +80.0°C, hyst = +75.0°C) sensor = thermistor
CPU?: +37.0°C (high = +80.0°C, hyst = +75.0°C)
(crit = +88.0°C)
Before taking the readings, I ran sensors -s to set the min/max values.
Now my output starts making sense and I can actually monitor any changes.
PS.
At the time of writing this article, website http://www.lm-sensors.org/ was down for multiple days in a row. I can only hope, that project personnel solves the issue with the web site and it is up at the time you're seeing this.
