When a mechanical switch like “button switch” is pressed, it conducting the electricity along with the noisy signals. This could be a major problem for false activation of the other circuits. This Noise is commonly produced by the switch because of the collision of internal components of the switch, which is called as switch bouncing. To cleans up noisy signal from mechanical switch we are using Debounce circuit.
What is Switch Bounce?
Switch bouncing is a phenomenon that occurs when a human presses a mechanical button and it produces multiple small, rapid signals instead of a single clean signal. When a microcontroller is connected to a mechanical switch, it may interpret one press as several clicks. This effect is called switch bouncing.
What is a Debounce Circuit?
A debounce circuit is a specially designed circuit used to prevent noisy signals or multiple switch presses that occur within a few milliseconds. The circuit filters out the noise when the switch is pressed once. As a result, a single press is considered as a single clean output signal.
The Debouncing circuit is used in different devices of,
- Microcontroller projects
- Digital counters
- Keypads
- Control panels
- Embedded systems
Why is Debouncing Important?
The debouncing circuit is essential in microcontrollers and other sensitive electronic circuits. Without debouncing, the switch may count multiple presses at the same time and read a single press as multiple presses. A relay circuit may turn ON and OFF rapidly, and the microcontroller may misread the input signal.
Types of Debounce Circuits
The debounce circuit is categorized as three, which are
- Hardware debounce Circuit
- Software debounce.
Hardware Debounce Circuit
In hardware debounce circuit using physical electronic components like Resistors, RC network, Schmitt triggers, logic gates and flip flop circuit to eliminating the false triggering or switch bouncing. This components based circuit works together and filter the unwanted noise signals. The circuit only passing through the single high quality signal this is known as hardware debouncing.
Software debounce
The software debouncing means the code is implemented in the microcontroller to prevent the false signal from the mechanical switch. The programming code first reading the switch state and when switch pressed, it analyze the pressing and engaging after some seconds of delay.
After the delay it repeatedly monitor the switch state. if the signal is matching with the code provided will only works. The advantage of this is no additional circuit is needed to clean the noisy signal from the button switch.
Hardware vs Software Debouncing
| Feature | Hardware Debounce | Software Debounce |
|---|---|---|
| Extra components | Yes | No |
| Accuracy | Very high | High |
| Cost | Slightly higher | Free |
| Response speed | Fast | Slight delay |
| Flexibility | Low | Very high |
Conclusion
The debounce is very small because very few number of electronic components is using in it. But it is a critical part in digital system for smooth working of the device. Which will gives a clear, stable and proper input signal when the mechanical button pressed. My recommendation is to implement hardware and software based technique to completely avoid false input signals.
