A simple project to trigger the shutter on my Pentax SLR via the infrared
remote control protocol when an attached distance sensor detects an object.

There are two variants: one activates the shutter if an object is detected in
a defined range between two distances; the second activates if the voltage out
of the sensor changes by a certain amount between two sample passes (this is
named with the suffix _delta).

Currently neither variant does any conversion of output voltages from the sensor
to distances. All thresholds etc. are expressed in terms of the values reported
by analogRead(), i.e. the output voltage of the sensor, normalised to the
voltage AREF (normally 5V) and expressed as a 10bit unsigned integer.

This makes use of the ir_remote library stored in another repository by that
name.