NSA320 fan speed

Hi y'all,

would love to make my nsa320 more silent (fan speed is set to full with debian - kernel 3.15).

solution with lmsensors and pwmconfig doesn't work (pwmconfig doesn't find any pwm compatible fans).

Anyone succeeded in taking control of their fan ?

I don't remember if it is for both, but for at least one of the NSA32x, the fan is entirely controlled by an MCU, and not configurable.

only resistor mod

zzds Wrote:
-------------------------------------------------------
> only resistor mod

Hi zzds,

Suppose I want to disable the watchdog pernamently in the NSA325 (without worry about GPIO setting in u-boot), how would I approach this at hardware level? in a similar way that you'd do resistor mod to the fan?

Thanks for any hint or thoughts!

-bodhi
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Edited 1 time(s). Last edit at 07/08/2015 04:04PM by bodhi.

@bodhi, assuming the MCU has visible pins and isn't a BGA you can get specsheets or carefully measure them with a multimeter and see what pins do the power-cut trick.
If it works like a dumb switch you just need to short them (bypassing the MCU, that will happily trigger whenever it feels like it, but will no more have any effect).

A more extreme measure or the only thing possible if it is a BGA would be to desolder the damn MCU alltogether and see if everything still runs fine (apart from the fan that can be soldered to any suitable power trace or you can short the old traces that feeded power for the fan to the MCU and the traces that took power from the MCU to the fan header).

I'm not very happy at the idea of dismantling my NSA325v2 again, but if you really need it I can do some recon work to find out what chip is the MCU and if something can be done at the hardware level.

Less-retarded designs like D-link 320L have a MCU accessible over a serial connection and can receive commands to control the fan or other stuff.

@bobafetthotmail,

Thanks for the offer! But I am actually not confident with my electronics skills yet to do that kind of modding! wish I had took more of these classes in college :)) but I guess I could practice it on a cheap $5 Pogo Mobile doing SATA mod...

> Less-retarded designs like D-link 320L have a MCU
> accessible over a serial connection and can
> receive commands to control the fan or other
> stuff.

Yup! This watchdog is a pain in the butt the way they designed it.

-bodhi
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Hi,

on both of my NSA320 boxes the resistor mod is used to calm
the original fan down to a reasonable value, but nevertheless here are some hints
if somebody has time and wants to look a little bit into the details,..

if you look in the original sources which were published by zyxel
you see how to read out the mcu status in mcu.c ,.. and the datasheet of the holtek
mcu is also easily found, but is not very instructive because it is a general purpose mcu
and seems to be programmed specifically by Zyxel in its internal rom,..

in the newer devicetree implementations for the NSA320 however the
gpio pins 14, 16, 17 which are the relevant gpios for the

pmx_mcu_data,
pmx_mcu_clk,
pmx_mcu_act

signals of the mcu are not exposed outside to a driver, see kirkwood-nsa320.dts,..

I have looked into that already, but did not find any suitable documentation of devicetree
bindings for the special case, that an hwmon capable mcu is connected to gpio's,

only the normal way via i2c is defined, so without that the nsa3xx hwmon kernel module
will not work, meaning the compatible descriptions are simply not defined by the dts devs of the linux kernel,

what does work of course is the approach WarheadsSE used for his power_resume.sh script,
so one can poke around with the mcu data line a bit, like in the example below:

best wishes pbg4

# export mcu gpios
/bin/echo 14 > /sys/class/gpio/export
/bin/echo 16 > /sys/class/gpio/export
/bin/echo 17 > /sys/class/gpio/export

# 16 mcu-clk out, value 1
/bin/echo "out" > /sys/class/gpio/gpio16/direction
/bin/echo 1 > /sys/class/gpio/gpio16/value

# 17 mcu-act out, value 1
/bin/echo "out" > /sys/class/gpio/gpio17/direction
/bin/echo 1 > /sys/class/gpio/gpio17/value

# 14 mcu-data in, value 0
/bin/echo „in“ > /sys/class/gpio/gpio14/direction
#/bin/echo 1 > /sys/class/gpio/gpio14/value
# set 14 value 0
/bin/echo 0 > /sys/class/gpio/gpio14/value