Home automation controllers



Nathan and I have settled on a mini-pc for a smart whole house fan controller that turns off an AC and runs a fan when it's cooler outdoors, and turns off a heater and runs the fan when it's warmer outdoors and the air is dry enough so there's no chance of condensation:
TU System 128mb ram + 512mb flash + Desktop Linux = $115 from
http://www.ewayco.com/51-embedded-systems-100-PC-mini-ITX-low-cost/100-tu-low-cost-pc-thin-client-embedded-system.html
It uses 15 watts. Is there a way to reduce the power, and does it have 256 or 512M flash memory? It also comes with a wireless option.

We found Atmel BASIC constraining, altho your displays seem nice.

Does it have a Roman numeral arithmetic package? My first programming language did, with error messages like "wrong Roman constant."
We are planning to use 2 $44 TAI 8540A 1-wire RH & temp sensors from http://www.aagelectronica.com/aag/index.html?target=p_2.html&lang=en-us and a $27 DS9490R 1-wire adapter, with OWFS as a 1-wire driver, and an X10 interface, eg the $69 2414u from http://www.smarthome.com/2414u.html or Home Depot (are these too smart to program via linux?) with X10 controllers for an AC, a heater, 2 fans and a damper, eg $11 15 amp AM466s from http://www.x10.com/automation/am466_s.html
http://www.hobby-boards.com/catalog/index.php?cPath $ has more fun stuff.
We are also looking at bwbasic, which appears to be about as old as gwbasic. Here's an ASHRAE 55-2004 comfort calc done both ways: 50 CLO = 1'clothing insulation (clo) 60 MET=1.1'metabolic rate (met) 70 WME=0'external work (met) 80 TA.6'air temp (C) 90 TR.6'mean radiant temp (C) 100 VEL=.1'air velocity 120 RH'relative humidity (%) 130 PA=0'water vapor pressure 140 DEF FNPS(T)=EXP(16.6536-4030.183/(TA+235))'sat vapor pressure, kPa 150 IF PA=0 THEN PA=RH*10*FNPS(TA)'water vapor pressure, Pa 160 ICL=.155*CLO'clothing resistance (m^2K/W) 170 M=MET*58.15'metabolic rate (W/m^2) 180 W=WME*58.15'external work in (W/m^2) 190 MW=M-W'internal heat production 200 IF ICL<.078 THEN FCL=1+1.29*ICL ELSE FCL=1.05+.645*ICL'clothing factor 210 HCF.1*SQR(VEL)'forced convection conductance 220 TAA=TA+273'air temp (K) 230 TRA=TR+273'mean radiant temp (K) 250 TCLA=TAA+(35.5-TA)/(3.5*(6.45*ICL+.1))'est clothing temp 260 P1=ICL*FCL:P2=P1*3.96:P3=P1*100:P4=P1*TAA'intermediate values 300 P508.7-.028*MW+P2*(TRA/100)^4 310 XN=TCLA/100 320 XF=XN 330 N=0'number of iterations 340 EPS=.00015'stop iteration when met 350 XF=(XF+XN)/2'natural convection conductance 360 HCN=2.38*ABS(100*XF-TAA)^.25 370 IF HCF>HCN THEN HC=HCF ELSE HC=HCN 380 XN=(P5+P4*HC-P2*XF^4)/(100+P3*HC) 390 N=N+1 400 IF N>150 GOTO 550 410 IF ABS(XN-XF)>EPS GOTO 350 420 TCL0*XN-273'clothing surface temp (C) 440 HL1=.00305*(5733-6.99*MW-PA)'heat loss diff through skin 450 IF MW>58.15 THEN HL2=.42*(MW-58.15) ELSE HL2=0'heat loss by sweating 460 HL3=.000017*M*(5867-PA)'latent respiration heat loss 470 HL4=.0014*M*(34-TA)'dry respiration heat loss 480 HL5=3.96*FCL*(XN^4-(TRA/100)^4)'heat loss by radiation 490 HL6L*HC*(TCL-TA)'heat loss by convection 510 TS=.303*EXP(-.036*M)+.028'thermal sensation transfer coefficient 520 PMV=TS*(MW-HL1-HL2-HL3-HL4-HL5-HL6)'predicted mean vote 530 PPD0-95*EXP(-.03353*PMV^4-.2179*PMV^2)'predicted % dissatisfied 540 GOTO 580 550 PMV999!:PPD0 580 PRINT TA,RH,CLO,PMV,PPD
19.6 86 1 -.4778556 9.769089
After removing the comments with something like
sed "s/'.*//;" gwfile.bas > bwfile.bas and adding back 'THEN's which bw complained were out of spec, eg in
410 IF ABS(XN-XF)>EPS GOTO 350
we got
19.6 86 1 -0.4778564 9.7691115
which seems close enough :-)
Nick
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snipped-for-privacy@ece.villanova.edu wrote: ...

http://www.ewayco.com/51-embedded-systems-100-PC-mini-ITX-low-cost/100-tu-low-cost-pc-thin-client-embedded-system.html
Have you considered one of the gumstix computers? They may not be any cheaper but the base configuration gives you a couple of serial ports and only uses about half a watt, less when idle. They can run Linux and use CF memory.
http://docwiki.gumstix.org/Frequently_asked_questions/Heat_and_power
Then again, how fast a computer do you need for this kind of stuff? Have you considered a PDA? They come with their own display and are pretty thrifty with the power requirements.
For that matter, you might even go so far back as the famous Radio Shack Model 100 which crops up on Ebay for $20 or so pretty regular. It only uses a watt or so and has basic built in. :)
Anthony
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We just looked at that. No USB port?

Sounds good. I wonder if we can store everything in the TU flash and power down the power supply 99% of the time.
http://docwiki.gumstix.org/Frequently_asked_questions/Heat_and_power

A 60 Hz Turing machine might work :-)

That's sorta where we started.

Right... I bought one of those for engineering calcs when I worked for Control Data, over humongous objections :-) I have something older in my attic with cassette tape I/O.
Nick
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