>> On 7/26/2010 1:50 PM, Alexandre Semedo wrote:
>>     =20
>>>    I need to develop a system to control a simple *air conditioning
>>> button*-> it should include two relays and have a real time clock.
>>>    Besides it should have at least two buttons for input and some
>>> visual display(example c code would be a plus).
>>>    I intend to program it in C. Does anyone know of a development
>>> board that is appropriate for this project?
>>>     Where i can buy one?
>>> Alex.

On 7/26/2010 5:34 PM, Alexandre Semedo wrote:
> the problem is that i have this big room with a "Sanyo" air conditioner
> that should be switched on or off based on the number of people inside..
> the thermostat in auto mode is useless.
>
> I would like to get a off-the-shelf development kit with all the
> components ready (relays/input buttons/real time clock/visual
> display) the programming would be the easier part for me.

Were you planning on having the microcontroller count the people
as they enter and leave the room?  If so, that's a tough project
to do with high confidence that the count in always correct. :-)

Are you going to use the real time clock to implement wall clock
time?  And then turn the air conditioner on at a certain time of
day and then turn it off at a later time of day -- making the
assumption that the number of people in the room is always fixed
by time of day (and day of week)?

If that's the case, you can buy off the shelf thermostats that
implement time of day mode switching.  You can set it to cool at
a specific time of day and not-cool at a later time (just set the
temperature to a low value to keep the air conditioner running).
One specific model is a Robertshaw item 9610 (I have one at home).
Such thermostats are inexpensive & quite common in the US as they
are mandated by various energy reduction laws.  I expect you can
get something similar in Portugal.

If you do build one, there's another option to consider.  Why do
you need a microcontroller at all?  Just have a small power supply,
a toggle switch, and whatever relays that are needed to interface
with the Sanyo air conditioner.  The toggle switch energizes or
de-enegizes the relay(s) as needed.  Flip the switch on when you
want air conditioning.  Flip it off when room is too cool or
enough people leave for the day.

						Lee Jones

--=20
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