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posted on October 11, 2004, 7:21 am
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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
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
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
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 $150 and work out the development stuff onto a
card for yourself.
Put that inside an outdoor electrical box with some foam and maybe it
will run outside for a while.
I think for a project like this you might want to think slightly
smaller. Do you really need all those capabilities?
T.
Re: Low-power device recommendation
hmm and whats going to happen at night ?
easy
hard
very hard
foget it
NO WAY
now your funny
so do it in microcontroller ! perl and python can take care of the
data on the server
definitelly NOT Linux
Pozdrawiam.
--
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Re: Low-power device recommendation
Batteries, mon! :)
Why? From what I can gather TS-7200 consumes about 1.7W tops - easily doable
with solar power & batteries. I'm not too technical so 'fraid programming a
microcontroller will be too complicated. Even if I managed it (read: ported
weather station polling software to a microcontroller), consider this: it's
going to be a standalone unit, and connected to servers only via Internet
(Ethernet or serial PPP + GPRS modem). It will need to send off data
periodically to the server. Can a microcontroller handle this?
Peter
Re: Low-power device recommendation
Never mind, I found the answer... TINIm400
(http://www.ibutton.com/TINI/index.html ) fits the bill perfectly: dual
serial ports, ethernet, 1-wire interface (which I need for weather station
anyway), Java runtime, PPP support, cheap (70$ or so + development interface
100-150$). My only reservation about this board is that it plugs into SIMM
connector which means I'll have to connect all physical connectors (serial
etc) to it somehow. Also, it takes regulated 5V while all solar
panels/batteries I've been able to find are 12V.
Re: Low-power device recommendation
about
interface
You will need to regulate the solar cell output. If you want the thing to
work at night you will also need battery power. Look at a shunt regulator
for the charging the battery and a DC/DC converter to go down from 12V to
5V.
Peter
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Re: Low-power device recommendation
OK, point me towards a cheapo MC that has 2 serial ports + 1-wire interface.
Basic Stamp could work, but it's awfully expensive for it's functionality -
Maxim's TINI sells for ~80$ (2 serials + 1wire + ethernet + Java + ssh
access + ftp access + godknowswhatelse)
Peter
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