4 detecting input events, Detecting input events - 9, Input event mask register, bit map - 9 – Kontron CP381 User Manual
Page 51: Input event polarity register, bit map - 9, Input status register, bit map - 9, Cp381 configuration
CP381
Configuration
ID 24107, Rev. 01
© 2002 PEP Modular Computers GmbH
Page 4 - 9
4.3.4
Detecting Input Events
Detecting events on input means that the CP381 hardware can supervise the input ports upon
their changing state and without being continuously polled. This mode is controlled by three
control registers. In the Input Event Mask Register, individual input events can be enabled
which should be monitored. In the Input Polarity Register the direction of the change-of-state
is set. Detected events are reported in the corresponding Input Event Status Register.
Table 4-6: Input Event Mask Register, Bit Map
Bits
Type
Default
Function
31-30
r/w
0
Not used
29 - 0
r/w
1
Input event mask bits
Note...
A set bit means that event detection is disabled for the corresponding input port.
Table 4-7: Input Event Polarity Register, Bit Map
Bits
Type
Default
Function
31-30
r/w
0
Not used
29 - 0
r/w
0
Input event polarity bits
Note...
A bit setting of 0 bit means that an event is detected when the input port
changes from 0 to 1 whereas a setting of 1 means that an event is detected
when the input changes from 1 to 0.
Table 4-8: Input Status Register, Bit Map
Bits
Type
Default
Function
31
r/w
0
Input latch-on-event status flag
30
r/w
0
Input compare status flag
29 - 0
r/w
0
Input event status flags
Note...
A set bit means that an event was detected on the corresponding input port.
Events must be cleared by writing a "1" to the corresponding input event flag.
Otherwise, consecutive events on the same input would no longer be detected.