CN103281057A - Filtering method for input signal - Google Patents

Abstract

The invention discloses a filtering method for an input signal. Based on a shifting register, the method specifically comprises the following steps of receiving the input signal by the shifting register, and sampling the input signal; recording the current state and the historical input state of a digital input port by an integer variable by the shifting register, putting the current input to the lowest position of the integer variable, and leftwards moving the former input state for one site; confirming the state change of the integer variable, and filtering where the lowest N sites of the integer variable is 0 or 1, wherein N is a natural number which is greater than 1; and presetting a pulse period, determining the rising edge or the falling edge of the input signal according to the integer variable, confirming the input pulse period of the current input port, and filtering out the pulse which is less than a preset pulse period value. The method disclosed by the invention is used for filtering the input twice, is safe and reliable, and is capable of setting the filtering range of the two filtering processes per se, thereby being applicable to most PCBs (printed circuit board) on elevators and escalators.

Description

A kind of filtering method of input signal

Technical field

The present invention relates to a kind of filtering method of input signal.

Background technology

Interference from signal source body or transducer all to be arranged in the various systems of industrial automation, in order accurately controlling, must to eliminate the interference in the input signal.In the environment, a series of interference can cause data distortion, fluctuation at the scene, adopt this software filtering reliability height, good stability.

Summary of the invention

Technical problem to be solved by this invention is to overcome the deficiencies in the prior art, and a kind of filtering method is provided, and in the staircase by mainboard control, can effectively reduce input and disturb the influence that elevator safety operation is caused.

The present invention specifically solves the problems of the technologies described above by the following technical solutions:

A kind of filtering method of input signal, described method specifically may further comprise the steps based on shift register:

Step (1) adopts shift register to receive input signal, and input signal is sampled;

The described shift register of step (2) is imported data with an integer variable record digital input port current data and history, and present input data is put to the lowest order of integer scalar, and the input data of back are to moving to left one;

Step (3) is determined the state variation of described integer variable, carries out the filtering processing when the minimum N position of integer variable is 0 or 1, and wherein N is the natural number more than 1;

Step (4) preestablishes the cycle of pulse, when input signal is in rising edge or trailing edge, determines the input pulse cycle of current input port, filters out less than the pulse that preestablishes the pulse period value.

As a kind of optimal technical scheme of the present invention: rising edge or the trailing edge of input signal are judged by integer variable in the described step (4).

The present invention adopts technique scheme can produce following technique effect:

Input filtering method of the present invention carries out the pulse less than set point after the cycle of filtering after the filtering with shift register, and input signal is transferred to and can provide for the voltage that CPU gathers from incoming level by last figure circuit, then by carrying out filtering.This method is only imported with integer variable record several times current and before, and current input is kept at lowest order.Determine just during value after the input of continuous several times is variation that input state changes, otherwise be considered as disturbing, finish a filtering.Whenever input be in lifting along the time, check the cycle when prepulse, the elimination cycle is finished secondary filtering less than the pulse of set point.

This method can be carried out twice filtering to input, and is safe and reliable, and can set up the filter area of twice filtering on their own, applicable to the most of pcb board on elevator, the staircase.

Description of drawings

Fig. 1 is the flow chart of the filtering method of input signal of the present invention.

Embodiment

As shown in Figure 1, the present invention relates to a kind of filtering method of input signal, described method specifically may further comprise the steps based on shift register:

Step (1) adopts shift register to receive input signal, and input signal is sampled;

The described shift register of step (2) is imported data with an integer variable record digital input port current data and history, and present input data is put to the lowest order of integer scalar, and the input data of back are to moving to left one;

Step (3) is determined the state variation of described integer variable, carries out the filtering processing when the minimum N position of integer variable is 0 or 1, and wherein N is the natural number more than 1;

Step (4) preestablishes the cycle of pulse, when input signal is in rising edge or trailing edge, determines the input pulse cycle of current input port, filters out less than the pulse that preestablishes the pulse period value.Wherein, the rising edge of input signal or trailing edge are judged by integer variable.

The concrete course of work of the present invention is as follows:

Input is sampled, result with this sampling of shift register record, Input is the sampled value (1 bit) of current input, Input_char is an integer variable, it can be the 16bit data, also may be defined as 32 bit data, current input is put into the lowest order of this integer variable, input state before is to moving to left 1.Program is as follows:

if(Input == 1)

Input_char = (Input_char << 1) + 1;

else

Input_char <<= 1;

Observe this integer variable Input_char, adopt a variable to record a digital quantity current data and continually varying historical data thereof, the data length that can record depends on the length scale of integer variable, and data structure is simplified very much.The user can utilize this variable further to carry out filtering and handle, and is 0(or 1 as the continuous several times state of this variable), namely its minimum some positions are 0(or 1), then confirm this state variation.When being 4 times as filter times, check minimum 4 of this variable, when minimum 4=0000, then this input validation is 0; Minimum 4=1111, then this input validation is 1; When minimum 4 be that data beyond 0000 or 1111 then keep former result, utilize simple statement to finish complete digital filtering like this, program is as follows:

if( (Input_char & 0x0f) == 0)

Input_result = 0;

else if( (Input_char & 0x0f) == 0x0f)

Input_result = 1;

Wherein variable Input_result is final input sample result.

By above-mentioned integer variable Input_char also can judgement place rising edge or the trailing edge of input, namely the some positions of lowest order are 1, inferior low some positions are 0, then can be judged as rising edge; Otherwise the some positions of lowest order are 0, and inferior low some positions are 1, then can be judged as trailing edge.For example the rising edge determining program is as follows:

if( (Input_char & 0x0f) == 0x03)

Input_Rising = Ture;

else

Input_Rising = Fault;

Said procedure is for 2 times that example is judged rising edge with filtering, and wherein whether variable Input_Rising is for being the judgement symbol of rising edge, and the present invention similarly just can judge rising edge or the trailing edge of digital signal with very succinct statement.

This method is only imported with integer variable record several times current and before, and current input is kept at lowest order.Determine just during value after the input of continuous several times is variation that input state changes, otherwise be considered as disturbing, finish a filtering.Whenever input be in lifting along the time, check the cycle when prepulse, the elimination cycle is finished secondary filtering less than the pulse of set point.

The present invention can be according to actual conditions, select filtered pulse whether, the border of the impulse magnitude that filters out is set.Therefore, any similar structures all belongs to the protection range of this patent.In addition, the non-creativeness that those skilled in the art carries out the technical program improves, and also belongs to the protection range of this patent.

Claims (2)

1. the filtering method of an input signal, it is characterized in that: described method specifically may further comprise the steps based on shift register:

Step (1) adopts shift register to receive input signal, and input signal is sampled;

The described shift register of step (2) is imported data with an integer variable record digital input port current data and history, and present input data is put to the lowest order of integer scalar, and the input data of back are to moving to left one;

Step (3) is determined the state variation of described integer variable, carries out the filtering processing when the minimum N position of integer variable is 0 or 1, and wherein N is the natural number more than 1;

Step (4) preestablishes the cycle of pulse, when input signal is in rising edge or trailing edge, determines the input pulse cycle of current input port, filters out less than the pulse that preestablishes the pulse period value.

2. the filtering method of a kind of input signal according to claim 1 is characterized in that: rising edge or the trailing edge of input signal are judged by integer variable in the described step (4).

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