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# SRFLIPFLOP

SR flip-flop

### Block Screenshot

### Contents

### Palette

### Description

This block describes the simplest and the most fundamental latch the SR flip flop. The
output **Q** depends of the state of the inputs
**S** and **R**. The output
**!Q** is the logical negation of
**Q**

If

**S**(Set) is pulsed high while**R**is held low, then the**Q**output is forced high, and stays high when**S**returns low;if

**R**(Reset) is pulsed high while**S**is held low, then the**Q**output is forced low, and stays low when**R**returns low.When

**S**and**R**are low,**Q(t)**takes the value of the previous output state**Q(t-1)**.When

**S**and**R**are both high, both**Q**and**!Q**take the low or high values; the state is unstable. Practically this case is forbidden.

The user can set the initial output state with **Initial Value**
parameter.

This block is almost used as a memory

The truth table of this block is:

Hold | ||||

Reset | ||||

Set | ||||

Forbidden state |

where * U* stands for "Unknown".

### Data types

The block supports the following types :

Inputs:

**R**: scalar. Scilab's int8 data type only.**S**: scalar. Scilab's int8 data type only.

A positive input is considered as logical 1, a negative or a null input as logical 0.

Outputs: scalar. Scilab's int8 data type.

### Dialog box

**Initial Value**Initial Value of the state Q. It must be int8 data type.

Properties : Type 'vec' of size 1.

### Default properties

**always active:**no**direct-feedthrough:**yes**zero-crossing:**no**mode:**no**regular inputs:****- port 1 : size [1,1] / type 5****- port 2 : size [1,1] / type 5****regular outputs:****- port 1 : size [1,1] / type 5****- port 2 : size [1,1] / type 5****number/sizes of activation inputs:**0**number/sizes of activation outputs:**0**continuous-time state:**no**discrete-time state:**no**object discrete-time state:**no**name of computational function:***csuper*

### Example

The following example presents a typical anti-bouncing application of the SR flipflop. The output graph shows the memory effect of the flipflop. Open this example in Xcos

### Interfacing function

### See also

- DLATCH — D latch flip-flop
- DFLIPFLOP — D flip-flop
- JKFLIPFLOP — JK flip-flop

### Authors

**Fady NASSIF** - INRIA

## Comments

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