Cbira la 10 mai 2018 06:47

2018-05-10T06:47:56Z

Cbira: Pagină nouă: In sequential circuits, any input variable that is not dependent of the system clock, is an asynchronuos input. The majority of these async inputs are coming from the mechanical de...

2018-05-10T06:47:29Z

Pagină nouă: In sequential circuits, any input variable that is not dependent of the system clock, is an asynchronuos input. The majority of these async inputs are coming from the mechanical de...

Pagină nouă

In sequential circuits, any input variable that is not dependent of the system clock, is an asynchronuos input. The majority of these async inputs are coming from the mechanical devices like the 4 push-buttons on the devboard. Besides being async, these signals are not perfectly rectangular, because the mechanical elements inside the buttons need a small time to get stable. For this short time, the generated signal contains multiple spikes, what may prevent correct functioning of other conntected circuits (it is behaving as a high-frequency signal). We will solve this problem, by ignoring the problematic period of time (a few milliseconds). The Debounce circuit below, receives on the input, a signal similar to '''in''' from the below figured, and generated a perfect rectangular output signal ('''out''' in the below picture).

[[Fișier:debounce1.png|Async input and debounced output]]

== Implementation of a debounce circuit ==

<syntaxhighlight lang="Verilog">
module Debounce(
output out,
input clock,
input in
);

parameter limit = 20'd650000;

reg [19:0] counter;
reg hit;

assign out = (counter == limit);

always@(posedge clock) begin
if(!in) begin
counter <= 0;
hit <= 0;
end else if(counter == limit) begin
hit <= 1;
counter <= counter + 1;
end else if(in & !hit) begin
counter <= counter + 1;
end
end

endmodule
</syntaxhighlight>

← Versiunea anterioară		Versiunea de la data 10 mai 2018 06:47
Linia 1:		Linia 1:
−	In sequential circuits, any input variable that is not dependent of the system clock, is an asynchronuos input. The majority of these async inputs are coming from the mechanical devices like the 4 push-buttons on the devboard. Besides being async, these signals are not perfectly rectangular, because the mechanical elements inside the buttons need a small time to get stable. For this short time, the generated signal contains multiple spikes, what may prevent correct functioning of other conntected circuits (it is behaving as a high-frequency signal). We will solve this problem, by ignoring the problematic period of time (a few milliseconds). The Debounce circuit below, receives on the input, a signal similar to '''in''' from the below ~~figured~~, and ~~generated~~ a perfect rectangular output signal ('''out''' in the below picture).	+	In sequential circuits, any input variable that is not dependent of the system clock, is an asynchronuos input. The majority of these async inputs are coming from the mechanical devices like the 4 push-buttons on the devboard. Besides being async, these signals are not perfectly rectangular, because the mechanical elements inside the buttons need a small time to get stable. For this short time, the generated signal contains multiple spikes, what may prevent correct functioning of other conntected circuits (it is behaving as a high-frequency signal). We will solve this problem, by ignoring the problematic period of time (a few milliseconds). The Debounce circuit below, receives on the input, a signal similar to '''in''' from the below figure, and generates a perfect rectangular output signal ('''out''' in the below picture).

	[[Fișier:debounce1.png\|Async input and debounced output]]		[[Fișier:debounce1.png\|Async input and debounced output]]

The Debounce circuit - Revizia istoricului

Cbira la 10 mai 2018 06:47

Cbira: Pagină nouă: In sequential circuits, any input variable that is not dependent of the system clock, is an asynchronuos input. The majority of these async inputs are coming from the mechanical de...