routine checks if the down db is at 255 in step 394 if yes the routine branches to step 410 if not the routine clears the up debouncer and decrements the down debouncer in step 398 then the routine checks if the down debouncer is at 22 in step 406 if not the routine branches to step 410 if yes the routine sets the down db to 255 and clears the tap cntr this indicates the user has pressed the down or close switch long enough to enable a movement command if the up lfc is greater than or equal to 4 the routine checks if the up db is at 255 at step 396 if yes indicating the user has pressed the up or open switch long enough to enable a movement command the routine branches to step 410 if not the routine clears the down debouncer and increments the up debouncer at step 400 at step 402 the routine checks if the up db is at 4 if not the routine branches to step 410 if yes the routine sets the up db to 255 and clears the tap counter at step 404 at step 410 the routine checks if the down.