Key-Scan
User Manual All information provided in this document is subject to legal disclaimers. © REALTEK 2019. All rights reserved.
317
First
Debounce
Column0
Column1
Debounce
Timer
Debounce
Timer
Full Scan
Scan
Interval
Timer
All Release
Timer
Full Scan
Row0
Row1
Full Scan
Scan
Interval
Timer
Debounce
Timer
Column
Pull Low
&
Row
Pull High
Column
Pull Low
Fig 16-4 Key-Scan timing
There are two work modes provided: Event Trigger Mode and Regular Scan Mode.
16.2.2.1
Event Trigger Mode
In Event Trigger Mode, key press or release event is stored in the key event FIFO only once in each key press and release operation.
16.2.2.2
Regular Scan Mode
In Regular Scan Mode, at each full scan, any key press event is stored in the key event FIFO until it is released (in this condition, only key press
event is stored in the key event FIFO). Fig 16-5 shows the difference of FIFO items between Event Trigger Mode and Regular Scan Mode during
a key press and release.
Key 1 Press
Key 1 Press
Key 1 Press
Key 1 Press
Key 1 Press
Key 1 Press
Regular Scan Mode
Key release
Key 1 Press
Key 1 Release
Event Trigger Mode
Key release
Fig 16-5 Difference of FIFO items between two work modes
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2019-05-15 10:08:03