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.
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.
