Can someone verified this circuit design? and is R55 not to big value?

DickCappels

Joined Aug 21, 2008
9,105
What do "Button 1" and "Button 2" connect to?
If it is a high impedance input then the value of R55 is no big deal, but if there is a load or a pull-up resistor connected to those points you might have problem.s
 

Ian0

Joined Aug 7, 2020
5,945
Only one real way to tell - look at the waveform on a ‘scope and see it there is still any switch bounce.
 

DickCappels

Joined Aug 21, 2008
9,105
Not quite enough information. What is type of chip used as the CPU, and what is the state of the internal pull-ups or pull-downs on those pins?

Ian0 has a good point - you should also have button debouncing in your firmware.
 

Ian0

Joined Aug 7, 2020
5,945
If you only scan the buttons in software once a second, you don’t need a debounce circuit. If the buttons are close to the MCU and they are not joined by long cables, you don’t need the zener, and if the MCU has pull-ups the you don’t need the external pullup resistor.
 
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