Do you have a question on Embedded electronics and controls? Ask our Expert, Paul Clarke

Actually, no, there are two air handlers, each servicing four rooms.  (There are actually more than 8 rooms, but these are the ony ones that are monitored.)  Each room makes the call to a specific air handler, but there is only one variable which controlls heating and cooling.  It's not very wise to run the heat on one and the AC on the other, as the heat from one set of rooms tends to leak generously into the others.  I also have dampers and booster fans in the system, but their operation is not relevant to the question of when to cool and when to heat.  They simply turn on or off as appropriate during the conditioning cycle, and that code is working perfectly well, as is the code which makes the calls for each room.  It is the decision point for cooling vs. heatig that is not working well.  When  the sun has gone down and the house is cooling, depending on the exact numbers I deploy into the working constants, the system may either switch to heating too soon, leaving some rooms overly warm (the heater does not come on, of course, but then neither does the AC because the system has switched to heating mode), or else the cooling cycle goes too long and some of the rooms get too cool, albeit passively.  The reverse is true when the temperature transitions from cool to hot outside.

It may help you to take a look at the ststus screen from the thermostat programming utility.  You can view this at http://fletchergeek.homelinux.net.  You cannot see or manipulate the controls from your site (I haven't implemented logins, yet, and security is enabled), but it may give you an idea.  Ther is a little bug in the passive reporting that I need to stamp out. Your view does not show the correct occupied status.

Here is the live schedule matrix:

01 08 16 45 01 75 86 55
02 07 00 00 00 75 86 55
03 08 02 30 00 76 83 55
04 07 02 00 01 75 85 55
05 07 00 00 00 74 85 55
06 08 12 30 00 78 83 55
07 08 02 30 00 77 85 55
08 07 00 00 00 77 85 55

The fields are: Sensor number, Schedule area ( Sun, Mon, Tue,...Sat, Weekdays, Daily, Now), Hour, Minute, Occupied (1=yes), Target, Maximum, Minimum.  This data is fed from a master schedule which determines when the temperatures change and when the rooms become unoccupied.

I understand perfectly well about the holidays.  I am in the same boat myself, so don't be surprised if it takes several days for me to respond.

Hi Paul,

Was my question beneath you or something?

As you had a answer or sorts then I guessed you were moving forward.

To be totaly honest I would not have gone about this at all. However I'm a embeded electroincs engineer so have little transmsstion experiance - and these distances count as that.

I would have put it over RS485 which can handel the SNR at this distance, but maybe not the data rate. Optics is another option but costly, What about over a network, VPN or even RF? but how would you get the DC voltages there?

Your question is not beneath me, just not maybe my expert area I'm not one to just cast option on things I'm not 100% on.

If I may be so bold, it happens I am a qualified expert on transmission systems, so I hope I am not out of line if I interject something.  If this is a commercial or industrial application, fiber is really not that expensive.  If this is for a personal project, it's a little different matter, but even then it is not all that far beyond the pale.  Non-plenum duplex fiber cable can be purchsed retail in lengths of 5000ft or longer for about $0.30 a foot.  Of course that means one will have to splice up to 5 reals together.  At this rate, 25Kft will cost about $7500.  Of course this is more expensive than coax, but not hideously so.  I would not attempt to supply power to the end terminmation remotely.  Rather, I would obtain a local source of power, even if it has to be solar.  Ethernet media converters can be had foir under $200 each, and there are standard devices available to convert from analog to digital signals and back.  For more in-depth analysis, I would need more details of the exact nature of the signals.

Hi Paul,

I had posted this in Experts Exchange but I think this is a better venue for the question and I am hoping you can help:

Hi Sir I am a biginer in embedded software development I can not translate the C program to hex program with Kiel microvisio soft ware please help

Paul, I already a H-bridge temperature controller that I want to replace with a MCU.

It's been awhile since I used the latest microcontrollers (MCUs) available on the open market.

These usually have their own developmental boards with an IDE software, etc.

I used Zilog's Z8 microcontroller back in the 90's.

I realize that the majority of EEs prefer these 3 candidates:

1) Atmel AVR

2) Microchip PIC

3) TI MSP430 (low-powered)

You may want to take a look at this application note from Microchip.  Sensored BLDC Motor Control Using dsPIC30F2010

also dsPIC30F2010  and  The dsPICDEM MCLV Development Board provides a cost-effective method of  evaluating and developing sensored or sensorless brushless DC (BLDC)  and Permanent Magnet Synchronous motor control applications.

Extreme Gratitude...I will follow up on this.

Frank

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