18 JVL Industri Elektronik A/S - User Manual - Integrated Stepper Motors MIS23x, 34x, 43x
2.2 Inputs
2.2.5 Digital inputs - features.
All of the eight I/O signals can be used as digital inputs. The sampled and possibly filtered
value of each input is stored in the Input’s register (reg. 18). Unlike the analogue inputs,
there is only one value for each digital input, so it must be configured to be either unfil
-
tered or filtered.
Unfiltered (high-speed) digital inputs are sampled every 100 µS (micro-seconds).
Filtered digital inputs are sampled every milli-second, and the filter value can be set in the
range 1 to100 mS, so the filtered input must be sampled to have the same logical value
for that number of samples in a row. Once an input has changed state after passing the
filtering, it will again take the same number of samples of the opposite logical level to
change it back. For example, if the filter is set to 5 mS and the start value is 0 (zero), the
input will remain at zero until three samples in succession have been read as 1 (one). If
the signal immediately drops down to 0 again, it will take three samples of zero in suc
-
cession before the register bit gets set to zero.
Note that filtering of the digital inputs does load the micro-controller, so if filtering of the
digital inputs is not needed, ALL the inputs can be selected as high-speed to reduce the
load.
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