KR100526938B1 - Method for receiving differential code at micom - Google Patents

Abstract

)으로 타이머를 초기화하는 제 2단계와, 상기 제 1단계에서 출력되는 펄스에 의해 마이컴의 인터럽트단자에 신호가 인가되고 다음 인터럽트단자에 신호가 인가될 때까지의 시간을 계수하고, 계수한 시간을 마이컴(4)에서 읽는 제 3단계와 상기 제 3단계에서 읽은 시간을 비교하여 마이컴(4)에서 읽은 시간이 기준주파수 시간(TO/2)과 증분시간(

)을 합한 시간보다 크면 데이터값을 1로 인식하고, 읽은 시간이 기준주파수 시간(TO/2)과 증분시간(

)을 합한 시간보다 작으면 데이터값을 0으로 인식하여 인식한 데이터 값을 어큐뮤레이터(accumulator)에 전송하는 제 4단계와, 상기 4단계의 어큐뮤레이터에 기록되어 있는 데이터를 직렬 데이터 버퍼(serial data buffer)에 저장하는 제 5단계로 구성되어 있고, 입력 데이터의 각 에지를 검출하여 에지에서 다음 에지까지의 주기를 측정하여 측정불능 영역이 생기지 않고 모든 펄스를 입력받아 정확하게 입력데이터를 수신할 수 있다.The present invention relates to a method of receiving a differential code from a microcomputer, and includes a first step of detecting an edge of input data to detect a period of a pulse, and a low interrupt (overflow interrupt) when a counter buffer is set. The sum of the pulse time and the incremental time (T0 +) so that the pulse time (T0), which is twice the reference frequency, can be measured before the time reaches.

In step 2 of initializing the timer and counting the time until the signal is applied to the interrupt terminal of the microcomputer and the signal is applied to the next interrupt terminal by the pulse output in the first step. The time read by the microcomputer 4 is compared with the time read by the microcomputer 4 and the third step, and the reference frequency time TO / 2 and the incremental time (

) Is greater than the combined time, the data value is recognized as 1, and the read time is the reference frequency time (TO / 2) and the incremental time (

) Is less than the sum of the time, the fourth step of recognizing the data value as 0 and transmitting the recognized data value to the accumulator, and the data recorded in the accumulator of the step 4 to the serial data buffer ( serial data buffer), and it detects each edge of the input data and measures the period from edge to next edge to receive all input pulses accurately without receiving an unmeasurable area. Can be.

Description

How to receive differential code at MICOM {Method for receiving differential code at MICOM}

The present invention relates to a method of receiving a differential code from a microcomputer. More specifically, a pulse generated at an edge of input data is generated, inputted to an interrupt terminal of a microcomputer, and data is distinguished by measuring a time until the next interrupt. The present invention relates to a method of receiving a differential code from a microcomputer capable of receiving desired data.

When sampling message signals, sampling faster than the Nyquist rate results in higher correlation between adjacent samples. This fact means that if the sample is encoded using the standard PCM method, the resulting encoded signal will contain excess information.

This means that the over-signal assignment resulting from the encoding of the common signal part with little change, and the signal part which is not essential for information transmission, is encoded. More efficient encoding is obtained by removing this excess information before encoding. In other words, by only encoding the difference between adjacent sample pulses, such unnecessary information can be eliminated and efficiency can be expected by quantizing and encoding only the difference between samples having a high correlation.

In this way, it is possible to deduce the magnitude of the signal to be changed in the future if the signal amplitude is changed by a certain time. This process is called prediction, and a differential code modulation (DPCM) method is used to modulate a sample signal using this prediction method. Adaptive delta modulation or adaptive differential code modulation are also included in this scheme.

Pulse phase modulation and demodulation are mainly used to transfer data over a single wire between digital systems, and the present invention relates to differential codes.

The operation of the differential code is described with reference to FIG. 1 as follows.

As shown in FIG. 1, the structure of the differential code is assumed on the assumption that the data signal transmitted from the transmission line is "000111".

Zero is represented at the same frequency as the synchronous clock (i.e. twice the baud rate), with the waveform leading from high to low if the leading edge was zero and from low to high if it was leading one.

1 is represented by the half frequency (same baud rate) of the synchronous clock. Like 0, the waveform is expressed as high when the leading edge is 0, and when the leading edge is 1, only the level changes to low.

In other words, when it is 0, the same frequency is output, and when it is 1, only half frequency is output and it is alternately complemented.

The data received by the microcomputer is transmitted in two forms, one in the data communication and the other in a pulse train composed of the same frequency as the baud rate, which represents the modulation rate of the serial transmission as the number of signals transmitted in one second. One is transmitted as a pulse train consisting of twice the frequency of the baud rate. The former is converted to 1 after decoding and the latter is converted to 0 after decoding.

As a method of distinguishing 0 and 1 by receiving data transmitted in the above two forms, a method of distinguishing data by determining a period of each pulse is used.

The simplest and most widely used method of determining the period of each pulse is the method using the pulse width measurement mode of the event counter in the microcomputer. The method operates to determine the period of data by measuring the width from the rising edge of the pulse to the falling edge.

However, the method of determining the period of each pulse by the above method can measure only the width from the rising edge to the falling edge of the pulse, so that the width of the pulse from the falling edge to the rising edge, that is, the negative portion, is measured. Unexpected problems are occurring.

Therefore, the present invention has been devised to solve such a problem, and an object of the present invention is to detect all edges of data so that a period from which a pulse of data cannot be measured cannot be detected, and a period from edge to next edge is measured. It is to provide a way to receive differential code from microcomputer.

Another object of the present invention is to input the pulse waveform generated at the edge of the input data to the interrupt terminal of the microcomputer, count the time until the interrupt occurs and the next interrupt to distinguish the data to receive the desired data It is to provide a way to receive the differential code in the microcomputer.

)으로 타이머를 초기화하는 제 2단계와 상기 제 1단계에서 출력되는 펄스에 의해 마이컴의 인터럽트단자에 신호가 인가되고 다음 인터럽트단자에 신호가 인가될 때까지의 시간을 계수하고, 계수한 시간을 마이컴에서 읽는 제 3단계와 상기 제 3단계에서 읽은 시간을 비교하여 마이컴에서 읽은 시간이 T0/2+

보다 크면 데이터 값을 1로 인식하고, 읽은 시간이 T0/2+

보다 작으면 데이터값을 0으로 인식하여 인식한 데이터 값을 어큐뮤레이터에 전송하는 제 4단계와 상기 4단계의 어큐뮤레이터에 기록되어 있는 데이터를 직렬 데이터 버퍼에 저장하는 제 5단계로 이루어진 것을 특징으로 한다.According to an aspect of the present invention, a microcomputer generates a code programmed to receive a transmitted data packet and output desired data, the method comprising: detecting a edge of input data to detect a period of a pulse; And enough time (T0 +) to measure up to a pulse time (T0) twice the reference frequency before the counter buffer is full and the time for overflow interrupt is reached.

The time until the signal is applied to the interrupt terminal of the microcomputer and the signal is applied to the next interrupt terminal by the pulse output in the first stage and the first stage of initializing the timer. The time read from the microcomputer is compared with the time read from the third step and the third step read from T0 / 2 +

Greater than 1, the data is recognized as 1, and the read time is T0 / 2 +

If it is smaller than 0, the data value is recognized as 0, and the fourth step of transmitting the recognized data value to the accumulator and the fifth step of storing data recorded in the accumulator of the fourth step in the serial data buffer. It features.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram for detecting the period of the pulse by detecting the edge of the input data according to the present invention.

Reference numeral 1 is an inverter used for a buffer for inverting input data, reference 2 is an integrator for delaying a waveform by the time constant by making time constants by resistors R and capacitors C. 3 is an exclusive ogate for exclusive OR of the waveform passing through the inverter and the signal passing through the integrator, and the reference numeral 4 receives a differential code by measuring a period of a pulse by receiving a waveform passing through the exclusive oragate. Microcomputer programmed to

3 is a timing diagram illustrating an operation of each section of a circuit for detecting an edge of input data and detecting a period of a pulse according to the present invention.

If the input data is assumed to be waveform a, it is inverted while passing through the inverter (b waveform), and the inverted waveform is delayed by the time constant by the resistor R and the capacitor C and outputted (c waveform). When the inverted waveform (b waveform) and the waveform (b waveform) inverted while passing through the inverter are delayed by the time constant while passing through the integrator, the output waveform (c waveform) is connected to exclusive oragate and is logically exclusive. Time constant pulses are generated at the edge (d waveform).

Hereinafter, the operation of the present invention having the above configuration will be described in detail with reference to FIG.

4 is a flowchart illustrating an operation of a method of receiving a differential code in a microcomputer according to the present invention.

In FIG. 4, abbreviations are used for simplicity of the drawings, and descriptions of the abbreviations constituting each block are as follows.

A: Accumulator

CF: Carry Flag

SBUF: Scrial data buffer

CNT: counter buffer to count the number of times "0" (2f0 frequency) is received

CNT-ROT: Number of bits received from start bit to stop bit

As shown in FIG. 4, in step 402, an edge of input data is detected, and in step 404, a timer is initialized. The method of initializing the timer is a time when a counter buffer is set. Determines whether the number of occurrences is 10.

If the number of received bits determined in step 426 is a stop bit, the stop bit is cleared (step 428) and the process proceeds to step 406 to prepare for receiving the next data interrupt, and the number of received bits is 10. Otherwise, the carry flag is set because it is a data bit (step 430).

보다도 적으면 이 데이터 값은 0이므로 432단계로 진행하여 0을 받은 횟수를 1증가시키고, 434단계로 진행하여 0을 받은 횟수가 2인가를 판단한다. 여기서,

는 증분시간을 의미하며, 그 시간은

이다.On the other hand, in step 420, the read time between interrupts is T0 / 2 +.

If the number is less than 0, the data value is 0, so the process proceeds to step 432 and the number of times of receiving zero is increased by one. here,

Means incremental time, which is

to be.

If the number of times 0 is determined to be 2 is not 2 in step 434, the process proceeds to step 406 to prepare for receiving an interrupt of the next data. The number of bits is increased by one (step 438), and the process proceeds to step 440 to determine whether the number of received bits is one. If the number of received bits is 1, the process proceeds to step 406. If the number of received bits is not 1, the process proceeds to step 442 and determines whether the number of received bits is 10.

If the number of the received bits is 10, it is a stop bit for notifying the end of the data, and an error is generated. If the number of the received bits is not 10, the error is generated. In step 446, the carry flag is cleared.

Then, the carry flag set in step 430 and the carry flag cleared in step 446 are inputted, and the accumulator is shifted to the left (step 448), and it is determined whether the number of received bits is 10 again. Step 450). If the number of received bits is not 10, there are more data values to be input, so the process proceeds to step 406 to receive the next data. If the number of received bits is 10, the accumulator value is a data value to receive the next data. The number of received bits is cleared (step 452), and the accumulator value is stored in a serial data buffer (step 454).

In this way, the pulse waveform generated at the edge of the input data is input to the interrupt terminal, the time from the occurrence of the interrupt to the next interrupt can be counted, and the data can be distinguished and received. Measure the period to the next edge.

As described above, according to the method of receiving the differential code according to the present invention, the microcomputer detects each edge of the input data and measures the period from the edge to the next edge to receive all pulses without inputting an accurate measurement region. Data can be received.

In addition, since the differential code is received using the microcomputer, the time for receiving the differential code can be minimized, and more accurate data can be received.

1 is a configuration diagram of a differential code.

2 is a circuit diagram for detecting an edge of input data according to the present invention;

3 is a timing diagram of FIG.

4A is a flowchart for explaining an operation of a method for receiving a differential code at a microcomputer according to the present invention;

4B is a flowchart for explaining an operation of a method of receiving a differential code at a microcomputer according to the present invention;

<Description of the code | symbol about the principal part of drawing>

1: buffer inverter 2: integrator

3: exclusive oragate 4: micom

Claims (4)

In the method of receiving the differential code in the microcomputer to generate the programmed code in the microcomputer, A first step of detecting a period of a pulse by detecting an edge of the input data; The sum of the pulse time and the incremental time (TO +) so that the counter buffer can measure up to the pulse time (TO), which is twice the reference frequency, before the time when the overflow interrupt occurs is reached.

A second step of initializing the timer, A third step of counting the time until the signal is applied to the interrupt terminal of the microcomputer by the pulse output in the first step and the signal is applied to the next interrupt terminal, and reading the counted time by the microcomputer 4; The time read by the microcomputer 4 is compared with the time read in the third step so that the reference frequency time (T0 / 2) and the increment time (

) Is greater than the combined time, and the data value is recognized as 1, and the read time is the reference frequency time (TO + 2) and the incremental time (

) Is less than the sum of the time and the fourth step of recognizing the data value as 0 and transmitting the recognized data value to the accumulator, A fifth step of storing data recorded in the accumulator of step 4 in a serial data buffer; Receiving a differential code from the microcomputer, characterized in that consisting of. (here,

Means incremental time, which is

being.) The method of claim 1, wherein the first step Inverting the input data using the inverter 1 used for the buffer, Delaying the waveform by the time constant by the integrator (2) consisting of the resistor (R) and the capacitor (C); The waveform passing through the inverter 1 and the signal passing through the integrator 2 are connected to an exclusive oar gate 3 so that a pulse width corresponding to the time constant of the integrator 2 at the edge of the input data is obtained. Generating and connecting this output waveform to the interrupt terminal of the microcomputer (4). Receiving a differential code from the microcomputer, characterized in that consisting of. The method of claim 1, wherein the fourth step (a) increasing the number of received bits by 1 when the data value is 1, and determining the number of received bits; (b) recognizing as a start bit when the number of received bits determined in step (a) is 1, and waiting to receive an interrupt signal of the next data; (c) recognizing a stop bit when the number of received bits determined in step (a) is 10, clearing the number of received bits, and waiting to receive an interrupt signal of the next data; (d) recognizing data bits when the number of received bits determined in step (a) is 2 to 9 and setting the carry flag to 1 Receiving a differential code from the microcomputer, characterized in that consisting of. The method of claim 1, wherein the fourth step (e) determining the number of times 0 is received from the counter buffer when the data value is 0; (f) increasing the number of received bits by one and determining the number of received bits; (g) recognizing it as a start bit when the number of received bits determined in step (f) is 1, and waiting to receive an interrupt signal of the next data; (h) recognizing a stop bit when the number of received bits determined in step (f) is 10 and generating an error; And recognizing the data bits when the number of the received bits is 2 to 9 in the step (e), and setting the carry flag to 0.

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