Low-power device recommendation

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 Hi all,
I'm new to embedded scene, and totally lost here. I'm looking to design a
totally stand-alone weather station and need to select a device for this.
Requirements are:

* low power consumption, ability to feed off single voltage (~12V solar
power)
* 2x RS232 ports
* Ethernet (10Mbit will be fine)

* solid-state disk (regular HDDs will consume too much power, and probably
won't work outdoors)
* ability to run "conventional" Linux that I can manage using shell access.
I'll also need to run Python and Perl on the box. Internet connectivity will
be either IPv4 (DHCP, ethernet), or PPP via serial. Having a small MySQL
server would be nice but I can probably live without it - it's probably
going to require too much disk space anyway
* CPU-wise requirements are very low - basically it needs to poll serial
port every second, and send off aggregated data every minute or so
* extremely stable - will need to run unattended for months
* weather-proof(able)
* cheap! This is my personal project!

Any recommendations appreciated!

Peter



Re: Low-power device recommendation


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Take a look at the TS 7000 from Technologics.  Looks like 2W power.  The
cpu might be a little more thab you need though.

http://www.embedded386.com /
Technologic Systems - Home Page


Joe


Re: Low-power device recommendation
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Power may be an issue, but lots of available documentation for the Linksys
WRT54G. Definitely cheap, $59.95. A Broadcom chip running a 200MHZ MIPS core,
The WRT54G  has 4MB memory and 16MB ram.
The WRT54GS has 8MB flash and 32MB ram.

Seattle wireless has some good documentation (www.seattlewireless.net).

Openwrt (http://www.openwrt.org ).

Paper at Sveasoft (http://www.sveasoft.com ), on how to weatherize the unit.

The serial port is accessible - requires a soldering iron.

--mikeb

Re: Low-power device recommendation


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<*Spits coffee all over keyboard*>

(In comp.os.linux.embedded, $60.00 is cheap, but
in comp.arch.embedded, $1.00 to $0.10 is cheap.)





Re: Low-power device recommendation
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Geez man, TS 7200 is 160$... definitely more expensive than Linksys unit!



Re: Low-power device recommendation
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The TS-7200 will have more capabilities and expandability.
The Linksys will be more fun for hacking.
Its really up to you.
T.

Re: Low-power device recommendation

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The guys at Technologic have a cheap board. www.embeddedarm.com, look at
the TS-7200. For about $390 you are into the embedded Linux arena. Or
just get the board for $150 and work out the development stuff onto a
card for yourself.
Put that inside an outdoor electrical box with some foam and maybe it
will run outside for a while.

I think for a project like this you might want to think slightly
smaller. Do you really need all those capabilities?

T.


Re: Low-power device recommendation
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TS-7200 seems like a good choice. Can anyone explain to a newbie what DIO
is?

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Maybe not. Guess I'll have to explore microcontroller arena, although it
sounds way too complicated at the moment.

Peter



Re: Low-power device recommendation
Why Linux?  If low power is truly your goal, look at a low power micro
Take a look at some of the lower power application at CoAutomation.com

http://www.coautomation.com/projects/index.htm



wrote:
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Re: Low-power device recommendation

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hmm and whats going to happen at night ?

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easy


hard


very hard


foget it


NO WAY


now your funny

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so do it in microcontroller ! perl and python can take care of the
data on the server

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definitelly NOT Linux

Pozdrawiam.
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Re: Low-power device recommendation
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Batteries, mon! :)

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Why? From what I can gather TS-7200 consumes about 1.7W tops - easily doable
with solar power & batteries. I'm not too technical so 'fraid programming a
microcontroller will be too complicated. Even if I managed it (read: ported
weather station polling software to a microcontroller), consider this: it's
going to be a standalone unit, and connected to servers only via Internet
(Ethernet or serial PPP + GPRS modem). It will need to send off data
periodically to the server. Can a microcontroller handle this?

Peter



Re: Low-power device recommendation
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  For an Ethernet/Web uC, look at

http://www.maxim-ic.com/products/microcontrollers/micro_ethernet.cfm
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3743/ln/en
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3744


Re: Low-power device recommendation
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OK, that will take care of Internet connectivity via Ethernet. What about
PPP dialup? Any MCs capable of doing this?

Thanks!
Peter



Re: Low-power device recommendation
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Never mind, I found the answer... TINIm400
(http://www.ibutton.com/TINI/index.html ) fits the bill perfectly: dual
serial ports, ethernet, 1-wire interface (which I need for weather station
anyway), Java runtime, PPP support, cheap (70$ or so + development interface
100-150$). My only reservation about this board is that it plugs into SIMM
connector which means I'll have to connect all physical connectors (serial
etc) to it somehow. Also, it takes regulated 5V while all solar
panels/batteries I've been able to find are 12V.



Re: Low-power device recommendation

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about
interface

You will need to regulate the solar cell output. If you want the thing to
work at night you will also need battery power. Look at a shunt regulator
for the charging the battery and a DC/DC converter to go down from 12V to
5V.

Peter


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Re: Low-power device recommendation
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station
SIMM
(serial
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Be sure to put in a switchmode converter with MPPT to optimize the power
from the panel. A shunt converter set at a fixed voltage will be very
in-efficiant

/Klaus



Re: Low-power device recommendation
 >Also, it takes regulated 5V while all solar
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If you don't know about switching voltage regulators, please stop
thinking about building solar driven intelligent devices.

-Michael

Re: Low-power device recommendation
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Hey, we all gotta start somewhere! ;) Will have to learn this stuph about
voltage regulators I guess... this is a learning experience for me.

Peter



Re: Low-power device recommendation

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thats exactly what microcontrolers are for !

Pozdrawiam.
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Re: Low-power device recommendation
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OK, point me towards a cheapo MC that has 2 serial ports + 1-wire interface.
Basic Stamp could work, but it's awfully expensive for it's functionality -
Maxim's TINI sells for ~80$ (2 serials + 1wire + ethernet + Java + ssh
access + ftp access + godknowswhatelse)

Peter



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