need help with a triple key keyboard

Thread Starter

Suzanne Patricia Likeng

Joined Oct 20, 2018
1
Hello guys, i need help with a triple key keytboard. I have never design such system in the past and i would wish to know if somebody have already tackled this type of project.
thanks
 

danadak

Joined Mar 10, 2018
3,873
Normally keyboard is scanned in a N x M matrix to keep pin
counts down that UP package has to have. And in code you basically
create a state machine that looks at key sequences and modifies
key read based on last "mode" key that was pressed. Also as
a part of this a timeout f() that resets mode keyboard is in
after some limiting inactive time interval. Or you indicate on keyboard
mode it is in and force user, no matter how much elapsed time
has occurred between presses, to press another mode key to
return it to another or "normal" mode.

So you would have, in code, 3 tables, 2 dimensions, for key mapping,
corresponding to each mode. Read the matrix position of key just
pressed, and using last mode key pressed to select correct table,
and then use the M x N position detected as an address into table.

Regards, Dana.
 
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