Detect falling edge when signal value decreases to strictly negative value, and its previous value was nonnegative
Logic and Bit Operations
The Detect Fall Negative block determines if the input is less than zero, and its previous value was greater than or equal to zero.
The output is true (equal to 1) when the input signal is less than zero, and its previous value was greater than or equal to zero.
The output is false (equal to 0) when the input signal is greater than or equal to zero, or if the input signal is negative, its previous value was also negative.
The Detect Fall Negative block accepts signals of the following data types:
For more information, see Data Types Supported by Simulink in the Simulink® documentation.
Set the initial condition of the Boolean expression U/z < 0.
Specify whether the block performs sample- or frame-based processing. You can select one of the following options:
Elements as channels (sample based) —
Treat each element of the input as a separate channel (sample-based
Columns as channels (frame based) —
Treat each column of the input as a separate channel (frame-based
Note: Frame-based processing requires a DSP System Toolbox™ license.
For more information, see Sample- and Frame-Based Concepts (DSP System Toolbox) in the DSP System Toolbox documentation.
Inherited — Inherit
the processing mode from the input signal and delay the input accordingly.
You can identify whether the input signal is sample or frame based
by looking at the signal line. Simulink represents sample-based
signals with a single line and frame-based signals with a double line.
When you choose the
Use Input processing to specify whether
the block performs sample- or frame-based processing. The block accepts
frame-based signals for the input
u. All other
input signals must be sample based.
|Input Signal u||Input Processing Mode||Block Works?|
|Sample based||Sample based||Yes|
|Frame based||No, produces an error|
|Sample based||Frame based||Yes|
For more information about these two processing modes, see Sample- and Frame-Based Concepts (DSP System Toolbox) in the DSP System Toolbox documentation.
Set the output data type to
Double | Single | Boolean | Base Integer | Fixed-Point