F Ig. 8-6: Downwards Counter - Addi-Data PC104-PLUS1500 Technical Description

Functions of the board
b) Downwards counter
Function downwards counter:
The counter starts with the counting value = relaod value and decrements with
each valid edge. At the result of count 0, the counter is loaded with the reload
value at the following valid edge. An interrupt can be generated with the
overflow.
Software clear:
Software trigger:
Example downwards counter
Reload value = 9
Initialisation on rising edge
Interrupt is released
At the current result of count = 0, with the following valid edge the reload value is
reloaded and the interrupt enabled.
38
Deletes counter (= 0)
Sets counter (= reload value)
Fig. 8-6: Downwards counter
PC104-PLUS1500