Adding to Richard,

just take care of inserting a 10 ~ 100 msec (depending on what type of switch is used) delay between whenever is key sensed pressed/released and corresponding action is taken.

for example for only a single switch/key:

scan_loop

jnb key,$ ; waiting for a key press
call debounce_delay ; 10 to 100 m Sec.
jnb key,scan_loop ; check if key was intentionally pressed

call actions

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Regards

Babar/