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Python script to edit the X8DTL-iF Registry to control fan speed.
#!/usr/bin/env python
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
import sys
import argparse
from smbus import SMBus
from contextlib import contextmanager
# All register ceom from
CHIP_ID = 0x79
W83795_REG_BANKSEL = 0x00
# Fan Control Mode Selection Registers (FCMS)
W83795_REG_FCMS1 = 0x201
W83795_REG_FCMS2 = 0x208
W83795_REG_TFMR = lambda index: 0x202 + index
W83795_REG_TSS = lambda index: 0x209 + index
W83795_REG_SFIV_TEMP = lambda index: range(0x280 + index * 0x10, 0x280 + index * 0x10 + 7)
W83795_REG_SFIV_DCPWM = lambda index: range(0x288 + index * 0x10, 0x288 + index * 0x10 + 7)
W83795_REG_CTFS = lambda index: 0x268 + index
#Fan Output PWM Frequency Prescalar (FOPFP)
W83795_REG_FOPFP = lambda index: 0x218 + index
#Fan Output Nonstop Value (FONV)
W83795_REG_FONV = lambda index: 0x228 + index
#Hystersis of Temperature (HT)
W83795_REG_HT = lambda index: 0x270 + index
#Target Temperature of Temperature Inputs
W83795_TTTI = lambda index: 0x260 + index
#Read temperature
W83795_REG_VRLSB = 0x3C
W83795_REG_TEMP_READ = [0x21, 0x22, 0x23, 0x24, 0x1f, 0x20]
FANS = range(0,8)
TEMPS = range(0,6)
def bank(bus, value):
prev_value = w83795_set_bank(bus, value)
w83795_set_bank(bus, prev_value)
def w83795_set_bank(bus, bank):
assert bank in [0,1,2,3]
# Read current bank value
cur_bank = bus.read_byte_data(ADDRESS, W83795_REG_BANKSEL)
# If the bank is already set, nothing to do
if cur_bank == bank:
return cur_bank
# Change the bank
bus.write_byte_data(ADDRESS, W83795_REG_BANKSEL, bank)
# Return previous bank value
return cur_bank
def w83795_write(bus, reg, value):
Write into the given registry.
with bank(bus, reg >> 8):
return bus.write_byte_data(ADDRESS, reg & 0xff, value & 0xff)
def w83795_read(bus, reg):
Read the given registry.
if hasattr(reg, '__iter__'):
with bank(bus, reg[0] >> 8):
return map(lambda r: bus.read_byte_data(ADDRESS, r & 0xff), reg)
with bank(bus, reg >> 8):
return bus.read_byte_data(ADDRESS, reg & 0xff)
def to_degree(val, low=0, hi=127):
"""Convert hex value to degree."""
return val
def to_perc(value):
"""Convert hex value to percentage."""
return value * 100 / 255
def from_degree(value):
"""Convert degree to hex"""
value = max(min(int(value) + 1,127),0)
return value
def from_perc(value):
"""Convert perc to hex"""
value = max(min(int(value) + 1,100),0)
return (value * 255 / 100) & 0xff
def main():
# Read arguments
parser = argparse.ArgumentParser(description='Change SuperMicro X8 Fan Control.')
parser.add_argument('-m', '--mode', type=str, choices=['smart', 'cruise'], help='Set the fan mode: smart or cruise. smart: to use Smart Fan mode. cruise: to use Thermal Cruise mode.')
parser.add_argument('-p', '--pwm', type=str, help='Set Fan Duty (in percentage).')
parser.add_argument('-t', '--temp', type=str, help='Set Temperature (in Celsius) associated to pwm.')
parser.add_argument('-H', '--hystersis', type=int, help='Set Hystersis value in degree (0-15)')
args = parser.parse_args()
# Open SMBus
bus = SMBus(0)
print("Failed to open i2c bus (/dev/i2d-0). Make sure i2c-dev module is loaded.")
#Check if we have the right device.
vendor = w83795_read(bus, 0xfd)
chipid = w83795_read(bus, 0xfe)
#debug("vendor %s, chipid %s" % (vendor, chipid))
if vendor != NUVOTON_VENDOR_ID or chipid != CHIP_ID:
print("unexpected vendor %s, chipid %s" % (vendor, chipid))
# Check if Smarts Fan Control is enabled
if args.mode == 'smart':
# Check arguments
if not args.pwm or not args.temp:
print('pwm and temp are required')
pwm = args.pwm.split(',')
temp = args.temp.split(',')
if len(pwm) != len(temp):
print("pwm and temp must have the same number of values")
# Change Smart Fan Control value
for i in range(0,7):
p = pwm[i] if i < len(pwm) else pwm[-1]
tt = temp[i] if i < len(temp) else temp[-1]
print("Set Smart Fan Control %s%% - %sC" % (p, tt))
for t in TEMPS:
w83795_write(bus, W83795_REG_SFIV_DCPWM(t)[i], from_perc(p))
w83795_write(bus, W83795_REG_SFIV_TEMP(t)[i], from_degree(tt))
# Change Minimum PWM
for f in FANS:
w83795_write(bus, W83795_REG_FONV(f), from_perc(pwm[0]))
# Change critical Temp
for t in TEMPS:
w83795_write(bus, W83795_REG_CTFS(t), from_degree(temp[-1]))
# Set Smart Fan Control Mode T6FC - T1FC
w83795_write(bus, W83795_REG_FCMS1, 0x0)
w83795_write(bus, W83795_REG_FCMS2, 0x3f)
elif args.mode == 'cruise':
# Check arguments
if not args.temp:
print('temp is required')
temp = int(args.temp)
print("Set Thermal Cruise %sC" % (temp,))
for t in TEMPS:
w83795_write(bus, W83795_TTTI(t), from_degree(temp))
# Change critical Temp
for t in TEMPS:
w83795_write(bus, W83795_REG_CTFS(t), from_degree(80))
# Set Thermal Cruise Mode.
w83795_write(bus, W83795_REG_FCMS1, 0x0)
w83795_write(bus, W83795_REG_FCMS2, 0x0)
# Set hystersis
if args.hystersis:
ht = max(min(args.hystersis,15),0)
print("Set hystersis %sC" % ht)
# Change Smart Fan Control value
for t in range(0,6):
w83795_write(bus, W83795_REG_HT(t), ht)
if args.mode or args.pwm or args.temp or args.hystersis:
# Check if Smarts Fan Control is enabled
fcms1 = w83795_read(bus, W83795_REG_FCMS1)
fcms2 = w83795_read(bus, W83795_REG_FCMS2) & 0xff
# Default to show all data.
for t in TEMPS:
print("Temp%s to Fan mapping Relationships (T%sFMR)" % (t+1, t+1))
tfmr = w83795_read(bus, W83795_REG_TFMR(t))
fans= [i+1 for i in FANS if tfmr & (0x1<<i)]
print(' '.join(['Fan%s' % i for i in fans]))
print("Smart Fan Control Table (SFIV)")
temp = w83795_read(bus, W83795_REG_SFIV_TEMP(t))
print(''.join([("%sC" % to_degree(v)).rjust(6) for v in temp]))
dcpwm = w83795_read(bus, W83795_REG_SFIV_DCPWM(t))
print(''.join([("%s%%" % to_perc(v)).rjust(6) for v in dcpwm]))
ttti = w83795_read(bus, W83795_TTTI(t))
print("Thermal Cruise (TTTI): %sC" % (ttti,))
ctfs = w83795_read(bus, W83795_REG_CTFS(t))
print("Critical Temperature (T%sCTFS): %sC" % (t, to_degree(ctfs)))
ht = w83795_read(bus, W83795_REG_HT(t)) & 0b1111
print("Hysteresis (HT%s): %sC" % (t, ht))
tmp = w83795_read(bus, W83795_REG_TEMP_READ[t])
print("Current Temperature (TEMP%s): %sC" % (t, to_degree(tmp),))
for f in FANS:
fonv = w83795_read(bus, W83795_REG_FONV(f))
print("Fan%s Output Nonstop Value (F%sONV): %s%%" % (f+1, f+1, to_perc(fonv)))
#for f in range(0,6):
# w83795_write(bus, W83795_REG_FONV(f), 50)
#w83795_write(bus, W83795_REG_SFIV_DCPWM(0)[0], 50)
#w83795_write(bus, W83795_REG_SFIV_TEMP(0)[0], 85)
#w83795_write(bus, W83795_REG_SFIV_TEMP(1)[0], 85)
if __name__ == "__main__":

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amadeusrotundo commented Feb 27, 2019

Hey there, I gave your script a shot, it throws the following errors:

when I run it normally I get

Traceback (most recent call last):
  File "/usr/local/bin/smx8fancontrol", line 252, in <module>
  File "/usr/local/bin/smx8fancontrol", line 138, in main
    vendor = w83795_read(bus, 0xfd)
  File "/usr/local/bin/smx8fancontrol", line 96, in w83795_read
    with bank(bus, reg >> 8):
  File "/usr/lib64/python2.7/", line 17, in __enter__
  File "/usr/local/bin/smx8fancontrol", line 62, in bank
    prev_value = w83795_set_bank(bus, value)
  File "/usr/local/bin/smx8fancontrol", line 70, in w83795_set_bank
    cur_bank = bus.read_byte_data(ADDRESS, W83795_REG_BANKSEL)
IOError: [Errno 6] No such device or address

When I run sudo python3 /usr/local/bin/smx8fancontrol

  File "/usr/local/bin/smx8fancontrol", line 21, in <module>
    from smbus import SMBus
ModuleNotFoundError: No module named 'smbus'

Any idea?

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