Initial implementation of IPSO Timer object #3340
Based on: http://www.openmobilealliance.org/tech/profiles/lwm2m/3340.xml
"This IPSO object is used to time events and actions, using patterns
common to industrial timers. A POST to the trigger resource or On/Off
input state change starts the timing operation, and the timer
remaining time shows zero when the operation is complete. The
patterns supported are One-Shot (mode 1), On-Time or Interval
(mode 2), Time delay on pick-up or TDPU (tmode 3), and Time Delay
on Drop-Out or TDDO (mode 4). Mode 0 disables the timer, so the output
follows the input with no delay. A counter is provided to count
occurrences of the timer output changing from 0 to 1. Writing a value
of zero resets the counter. The Digital Input State resource reports
the state of the timer output."
NOTE: Only One-Shot Mode (mode 1) is implemented in this patch.
Signed-off-by: Michael Scott <mike@foundries.io>