Nut upsuser - Mar 2008 - [OT?] How often does/should NUT poll an UPS or my PSU?

Hello,

Maybe a little bit Off-Topic but:


QUESTION 1: How often does/should NUT poll an UPS or my PSU?


I have this question since I have a hardware design problem.


Hardware Description:
====================The PSU is modular (all power modules, like "ATX",
"P4", "ePCI", "SATA",
"Device" can be choosen as needed) where I have two type of Base
Boards:

    1)  Base Board 1
        only OVP/UVP protection and no other electronic (incl. USB)

    2)  Base Board 2
        Microcontroller supported PowerWhatch with USB and NUT support

On "Base Board 2" I have only to whatch the Uin,  Iin  and 
temperature,
which mean, I need two A/D-Converter and a temperatur sensor.  The "Base
Board 2" identify it self over the USB  port  by  using  an  I?C  EEPROM
conencted directly to the USB-Host  Controller.  (Tested  and  it  works
with my Evaluation Board from NXP;  I like success :-)

Now I am thinking to add a VERY Low-Cost  USB-Host-Controller  to  "Base
Board 1" to get at least the Uin and use a  simpel  A/D-Converter  which
then can be read over USB from NUT which then can consider to ignore it,
let the computer go into standby or shut the computer down.


QUESTION 2: Should I expose the value of the A/D  Converter  to  the
            USB port which let the ${USER} choose when to  shoutdown
            the computer or should I set fixed values with a Window-
            Discriminator and send only a "Under Voltage" signal?


So, this are not very difficult, since even  a  parallel2usb  controller
does not need a Microcontroller... :-)

The biggest problem are the ATX module where I like  to  get  the  Volt,
Ampere and Temperature like:

    1)  +12  V
    2)  + 5  V
    3)  + 3.3V
    4)  + 5  Vsb
    5)  -12  V
    6)  Temperature

So, this are effectiv 11 values to get on ONLY the ATX module.

On another mailinglist, someone suggest to forget  I?C  and  use  Maxims
1-Wire Technology and do Bit-Banging...  but there is a  timing  problem
with 1-Wire:  16.3 kbit/s

If I go the way with 1-Wire, I would put on the "Base Board 2" a 
Micro-
controller which  support  I?C and then put a I?C-Switch  onto  it.  The
first 5 ports would be each connected to one of the 5 Port/Module  Slots
on the "Base Board 2" which is needed to  identify  EACH  slot  and 
the
Module inserted.

Then on the Module I put a "Singel  Channel  1-Wire  Master" 
DS2482-100
which convert the I?C to 1-Wire...

And now it comes:  To get the 11 values described above, I have the need
for three "Quad A/D Converter" DS2450 (from the third there are only
two
used), a "High-Precission 1-Wire  Digital  Thermometer"  DS18S20  and 
a
"Silicon Serial Number" DS2401 (customisable) which identify the
module.

Now, the 1-Wire protocol say, you have to "scan" the 1-Wire bus to
know,
which devices are connected and get its ID and then you have to poll the
devices.  On the ATX module at start-up 5 devices and  then  continously
4 devices.

OK, this is done by the Microcontroller on the "Base  Board  2"  but 
it
seems I can not get the whole set of DATA in less then 3 seconds...

Result: NUT can not poll the PSU in less then 4 seconds...


QUESTION 3: Should I realy go the way with Maxims 1-Wire technology?


Now, going back to the website of NXP/Philips looking for I?C  stuff,  I
have found an "Quad A/D Converter" and "EEPROMS"  (maybe 
overkill)  but
currently not found a temperatur sensor (it is  desribed  but  have  not
found its part number).

So, I?C would do the stuff in less then 200 milli seconds which mean, it
is at least 15 times faster.


QUESTION 4: It is better to use I?C even if the, e.g. ATX  module,
            would be arround 4 US$ more expensive?


The avantage with I?C is, that I have only ONE protocol and its faster.

Thanks, Greetings and nice Day
    Michelle Konzack
    Systemadministrator
    24V Electronic Engineer
    Tamay Dogan Network
    Debian GNU/Linux Consultant


-- 
Linux-User #280138 with the Linux Counter, http://counter.li.org/
##################### Debian GNU/Linux Consultant #####################
Michelle Konzack   Apt. 917                  ICQ #328449886
+49/177/9351947    50, rue de Soultz         MSN LinuxMichi
+33/6/61925193     67100 Strasbourg/France   IRC #Debian (irc.icq.com)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
Url :
http://lists.alioth.debian.org/pipermail/nut-upsuser/attachments/20080318/a06ea594/attachment.pgp