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Controlling the Humidity with an Embedded Linux System

Issue 188

From Issue #188
December 2009

Dec 01, 2009  By Jeffrey Ramsey
 in
Using an inexpensive embedded Linux board and a few extra devices, you can control things like room humidity.

Listing 8. Perl Script setTargetHumidity

use CGI;
$query = new CGI;
$targetH = $query->param('targetH');
$SNMP_SET_CMD = "snmpset -v 1 -c private";
$SNMP_TARGET = "localhost";
$SNMP_TARGETHUM_OID = "targetHumidity .0";
$SNMP_TYPE = "i";

chomp($retVal = `${SNMP_SET_CMD} ${SNMP_TARGET}
      ↪$SNMP_TARGETHUM_OID $SNMP_TYPE $targetH`);

The humidity controller (Figure 6) has been keeping my music room within a humidity range that makes my Carlos Pina classical guitar quite happy (Figure 7). The work involved to build the system was a real pleasure. But the best part is sitting down to play the opening arpeggios in Bach's Prelude and hearing the notes ring true without retuning my guitar. It not only makes me smile, but I think it would make Bach smile as well.

Figure 6. Completed Humidity Controller with Humidifier and Dehumidifier Connected

Figure 7. Carlos Pina Classical Guitar

Resources

Listing 7 (the Complete User-Mode Application): ftp.linuxjournal.com/pub/lj/listings/issue188/10534.tgz

TS-7200 Main Board (from Technologic Systems): www.embeddedarm.com/products/board-detail.php?product=TS-7200

TS-RELAY8 Daughter Card (from Technologic Systems): www.embeddedarm.com/products/board-detail.php?product=TS-RELAY8

TS-ENC720 Enclosure (from Technologic Systems): www.embeddedarm.com/products/board-detail.php?product=TS-ENC720

Jeffrey Ramsey has been an embedded developer his entire career, and when not pouring through Linux kernel and driver source code, he can be found plucking a guitar. Jeffrey can be contacted at jeffreyramsey@e2atechnology.com.

______________________

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I really couldn't understand

Anonymous's picture
Submitted by Anonymous on Thu, 06/03/2010 - 00:25.

I really couldn't understand what a amancaes is?? what does if do anyways?? i could only understand that it indicates a very much greater degree of humidity, than at a corresponding height at Iquique, but how does it do that. Is an Amancaes also similar to Humidifier Filters. If this is so then why not keep a humidifier instead of a Amancaes. doesn't the both work same way.

explanation

Anonymous's picture
Submitted by Anonymous (not verified) on Thu, 11/11/2010 - 08:41.

Yes an amancaes is an ingenious device that can automatically control humidity - not only local humidity, but humidity in any other part of the world, remotely. It does this using the Iquique height factor to convert local humidity control (i.e. Linux kernel version/distribution) into remote humidifier filter command words. It is frankly one of the keys to Darwin's entire theory of natural selection, based on humidity and moss observation.

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