[Nut-upsuser] 24V DC ATX PSU with limited UPS functionality over USB

Arnaud Quette aquette.dev at gmail.com
Fri Mar 14 15:03:43 UTC 2008

[quickly passing by ; relocation is about to complete...]

2008/3/14, Charles Lepple <clepple at gmail.com>:
> On Thu, Mar 13, 2008 at 5:50 PM, Jean Delvare <khali at linux-fr.org> wrote:
>  > Hi Michelle,
>  >
>  >
>  >  On Tue, 11 Mar 2008 16:22:09 +0100, Michelle Konzack wrote:
>  >  > Hello Developers and *,
>  >  >
>  >  > I am working on a "24V DC ATX PSU" for Photopholtaik Systems which can
>  >  > have input voltages from 18V to 27.7 Volt and is entirely modular,
>  >  > which mean, you can select the desired module/s (up to 6) from ATX
>  >  > (96/144/240/300W), P4 (144W), SATA (82/305W) and Device (34/68/136W)
>  >  >
>  >  > And last not least, I want to build a "PowerWhatch" module which should
>  >  > be connected from the PSU to an internal USB port of the mainboard.
>  >  >
>  >  > Currently I do not know, whether I should use Maxims 1-Wire chips like
>  >  > the DS2450 which has four AD-Converter or a I²C/SMBus solution.  Both
>  >  > will work with the DS80C411 Microcontroller...
>  >  >
>  >  > Now the question to you:
>  >  >
>  >  > Since I do not want to reinvent the wheel, I like to use existing
>  >  > programs where I think, NUT is the perfect solution...  The problem is,
>  >  > HOW I have to deliver the data to it or how must I provide it?
>  >  >
>  >  > The "PowerWhatch" module picks only the Voltage and Amperes and
>  >  > Temperature from each of the 11 modules... and maybe it will store them
>  >  > for a while in a 8-16 kByte NV-RAM or something like this...
>  >  >
>  >  > If you have ideas or suggestions, please let me know.
>  >
>  >  Given that you are working on a PSU and not a UPS,
> I guess it depends on which part of the "limited UPS functionality"
>  Michelle is referring to.
>  If the PSU signals to the PC that it is time to shut down due to lack
>  of reserve power, then it might benefit from NUT's existing
>  infrastructure (granted, the "N" in NUT is often extra baggage...)

considering the support of PDU, the (my) aim to extend support to
Power Devices in general and the recent Integrated Power Management
(see below), both the "N" and the "U" are becoming more and more

But the "nut" name is well known, and I only consider a possible name
change for 3.0.
Although something like PDT (Power Device Toolbox) is less funky and
NewUT (pronounce niout, New UPS Tools) is still UPS focused...

>  > I am not sure that
>  >  nut is the best tool to interface with. Wouldn't it make more sense to
>  >  add one or more hardware monitoring chips in your PSU and connect them
>  >  to the motherboard's SMBus, and use a hardware monitoring driver in the
>  >  kernel to monitor all the values you are interested in? There are many
>  >  popular chips already supported by the Linux kernel, which can monitor
>  >  several voltages, temperatures and/or fans. And then there's a library
>  >  for applications to access the data easily.
> If you have a specific motherboard in mind, this is probably a good
>  plan, but not all motherboards with I2C make the bus available to
>  external devices.
>  Another advantage of going the HID PDC route (regardless of whether
>  NUT is involved) is that the device is essentially self-describing. If
>  the first version does not have a shutdown flag, but later versions
>  do, then very little driver code needs to change - just device
>  firmware.
>  Also, I believe that GNOME has a power monitor that works with HID PDC
>  devices out-of-the-box, which would be another bonus feature if you go
>  down the USB route.

hey Charles, haven't you looked at the NUT HAL support?
This is all about that, but not limited to HID/PDC (in fact, all the
NUT USB UPSs are supported)

Linux / Unix Expert R&D - MGE Office Protection Systems - http://www.mgeops.com
Network UPS Tools (NUT) Project Leader - http://www.networkupstools.org/
Debian Developer - http://people.debian.org/~aquette/
Free Software Developer - http://arnaud.quette.free.fr/

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