I just wrapped up a pcb for a remote display/ button panel based on a TM1638 LED mux chip (8 digits x 10 segments + 3 × 10 switches). My oh crap moment was realizing it should have provision for a piezo beeper.
Options might be:
● Drive an opto-isolator to turn on a beeper. A passive beeper might make some noise at ⅛ scan rate.
● Drive an opto-isolator with a parallel capacitor to hold it on between scan cycles. If I do that, I think I need to add a series diode to the driver chip to keep the cap from feeding back into the driver chip.
● Drive an opto-isolator, with a cap on the output side to keep the beeper going between scans.
In the last two cases, I'd use an active beeper.
Any thoughts or other ideas? Thanks.