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An interesting thing is that most remote controls send a unique first code that
can be identified for each and every button, as well as each and every remote
control. Some remotes will send a full data stream over and over as long as
you hold the button down, up to 48 bits per data stream. Other remotes will
only send this full data stream once for the first depression, and then a very
short repeat code usually of only one bit, to save on batteries.
The ICI2 recognizes the full codes, and discards the short repeat codes
unless you are holding a relay in position. If we didn't do this, we couldn't tell
one button from another! You will find that with some remotes, you need to
press the button twice to train the ICI2 to remember a certain button. This
means the remote you are using is using repeat codes. Other remotes just
require you to press and hold the button, so these are the ones that send the
same code over and over.
One other variance is the data rate from the remote. Generally most remotes
send at a rate of 2400 Hz time slices, but others send at only 1200 Hz time
slices. This presents a problem since the sample period will always lie in a
high or low portion of the subsequent data, meaning we will receive nothing
but ones or zeros. There is a speed jumper you can install to allow the ICI2 to
work with these remotes. If an incorrect speed remote control is detected, the
microcontroller emits a special beep to let you know the format is wrong. Then
you can switch the jumper over to the other speed and try again, then you will
get either a recognized beep if you have trained the button, or an unrecog-
nized beep if you have not.
When you train the ICI2, the micro controller looks at the IR data stream and
rejects those codes it sees as useless or unverified. The ICI2 looks at the data
from the remote sensor, makes sure it is not a repeat code, checks that it is
not the wrong speed, and then compares it to a previous send before saving
the new value in the Flash memory of the controller. That is why you have to
press the button twice on some remotes; so you can get the same code for
verification before saving.
When the ICI2 is normally receiving, it looks at the data stream, and com-
pares it to what was saved. If there is a match, the corresponding function is
run. If there are repeat codes within the allotted time, the same function is re-
peated continuously until the IR signal goes away.
The ICI2 stores eight codes, each of which are tied to a specific function
(see the on the top of the board layout). For example if you press a button that
you programmed on select 0, the volume will go up a single step. Press it
again, and it goes up another step. Press and hold, and the volume will go up
at the rate of the repeat code sent from the remote. In some cases it may be
rather fast, so you may have to find remotes that don't send so fast! We have
yet to find one that has been too fast, but we are sure some exist.
ICI2 Page 6
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