JPH0241269A - Detecting system for control signal - Google Patents

Abstract

PURPOSE:To obtain a detecting system for a control signal for improving its noise resistance by inhibiting the input of the control signal in a period term over a predetermined third time shorter than a first time after the control signal is established. CONSTITUTION:A print data signal D is led to a line l16 toward a printer 11, which receives it, inputs print data D and prints it. A MPU 14 sets a mask T signal MSKT during this period. Accordingly, the level of the input terminal i1 of an interrupt request circuit 16 is varied, and the level of a line l14 is fixed to a nonactive level of an interrupt signal INTT. The MPU 14 thereafter inhibits the generation of the signal INTT, simultaneously extracts from an interrupt program and executes other operation. This inhibiting period is continued for a predetermined specific time, after the specific time is elapsed, the signal MSKT is reset, and the generation of the signal INTT is allowed. Accordingly, a noise signal invaded during this inhibiting period is all removed, thereby completely preventing the state for disturbing the operation of the printer 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control signal detection method, and more particularly to a control signal detection method suitable for controlling a printing device or the like.

BACKGROUND OF THE INVENTION For example, an electronic cash register (hereinafter referred to as ECR) uses a serial dot matrix printer (hereinafter referred to as printer) as an output device for printing quantities, cash, etc.
The printer is controlled and driven by a control unit realized by a microprocessor, multiple gate arrays, memory, etc.

FIG. 5 is a block diagram showing the configuration of a conventional printer, and FIG. 6 is a time chart that does not show its operation. Referring to FIG. 5 and FIG. 6, the control unit 1 and the printer 2 are connected to each other by lines 11 to 12, and the printer 2 lowers the timing signal T when the timing for printing occurs and controls the printer 2. Notify Department 1 of the timing.

Print data D is output from the control section 1 to the printer 2I\ and printing is performed. For example, at time t1 when printing for one character is completed and the next print data D is received, the timing signal T is set to a low level to activate the printer 2 and notify the controller 1 via the line 12. The Mfj1 section 1 then outputs the next print data D, and printing operations are sequentially performed in the same manner. As described above, the timing signal T is a control signal for the printer 2 to perform a printing operation in synchronization with the control unit 1, and the period of the timing signal T is predefined by the performance of the printer 2, such as the printing speed.

Although the transmission of the print data D from the III control unit 1 to the printer 28 is fast, the process of the printer 2 receiving the data and executing the print operation takes time. However, in order to improve efficiency in (-), the period M from time t2 to time t3 from the output of data D to the fall of timing signal T shown in FIG.
That is, during the printing period, the micro 10 sensor (
(not shown) executes the movement fIP of the song, and the timing signal T
At time t4 when the falling edge of D is detected, the next print data D
is output to printer 2.

In the conventional technology, the control unit 1 detects the falling edge (hereinafter referred to as edge) e of the waveform of the timing signal T shown in the sixth [2ff(3)], and controls Δ for a certain period of time from the detection time t3. A control signal detection method is used in which the level of the timing signal T is later compared with a predetermined level to determine whether the timing signal T is present or not.

Problems to be Solved by the Invention However, in such a detection and processing method according to the conventional technology, for example, from time t2 when the output of print data D is finished to time t3 when the timing signal T falls, as shown in FIG. The detection operation was performed even during the period N in which the timing signal T was inactive. Therefore, due to the noise generated within the above period N, so-called "rvI distortion" or "whiskers" occur in the waveform of the timing signal 3T, causing malfunctions, and also during the period N, which should not be detected in the first place.
The noise waveform generated during the process was sometimes mistakenly recognized as a timing signal. Such tooling further led to a loss in overall processing time, contributing to a reduction in performance.

An object of the present invention is to provide a control signal detection method that solves the above-mentioned technical problems and significantly improves noise resistance.

Means for Solving the Problems The present invention provides edge detection means for detecting at least either a falling edge or a rising edge of a control signal input at a predetermined first time period; and after detecting the edge, a signal determining means for determining the level of the control signal by detecting the control signal again after a predetermined second time; The control signal detection method is characterized in that it includes a prohibition means for prohibiting input of the control signal within the periodic period.

Function: The control signal detection method according to the present invention detects the edge of the waveform of a control signal input at a predetermined first time period, and then detects the control signal again after a predetermined second time period. This establishes the control signal. After the control signal is determined, an operation based on the control signal is executed for a certain third period of time, and the input of the control signal is prohibited during the above-mentioned cycle period, thereby preventing noise and its influence.

Embodiment FIG. 1 is a block diagram showing the electrical configuration of a control signal detection method according to an embodiment of the present invention. The first timing signal T+, which is a control signal with a predetermined period based on the performance of the printer 11 such as the printing speed, is input to the filter 12 via the line 111, and the second timing signal T2
I was waveform-shaped through line/12
The signal is input to the fj1 section 13. In this example, the following:
Print data can be input to the printer 11 at the falling edge of the first timing signal T. Also, the first timing signal T
Second and third timing signals T, , T, which will be described later.

When referring to the general term, we use ``rrT''.

The first part 13 is composed of a central processing unit 14 realized by a micro 10 setter, a logic judgment circuit 15, a request circuit 16, etc. The operation of the first part 13 is defined by a clock signal (not shown).

The second timing signal T2 branches into two branches, one of which is input to the logic determination circuit 15 and the other to the interrupt request circuit 16. The logic determination circuit 15 is a means for detecting the edge of the waveform of the second timing signal T2, which is a control signal inputted at the predetermined period, and includes a plurality of gate arrays, memories, etc. (not shown). The logic of the second timing signal T2 is detected here, and
The data stored in the storage area (I21 not shown) of the MPU 14 is read out within a certain period of time, and a level check is performed by so-called "twice reading".

However, normally, the noise signal Z having a period shorter than the above-mentioned fixed period is removed by the above-mentioned twice reading, and the signal led out to the twice-reading raft is sent as the third timing signal T via the line /13. The signal is input to the timing signal input terminal TI of the MPU 14, and the logic of the timing signal T is determined.

In this way, the logic determination circuit 15 functions as a filter for the noise signal Z.

The MPU 14 and the interrupt request circuit 16 constitute means for prohibiting input to the timing signal input terminal TI within the fixed period after detecting an edge of the timing signal T, which is the control signal, based on the period of the timing signal T, which is the control signal; Next, its operation will be explained.

The MPU 14 receives the input third timing signals Q and T□ and generates an interrupt enable/disable signal (hereinafter referred to as mask T signal) based on the timing signal T.
K T via line 115 to interrupt request circuit 16
is input to one input terminal 11 of the . Mask T signal MSK
The time width and period of T are set in advance by the MPU 14 based on the clock signal, and for example, during the rising period, interrupts are allowed, and during the falling period jlj1, interrupts are prohibited.

The second timing signal T2 is input to the other input terminal 10 of the interrupt request circuit 16, and the second timing signal T2 and the mask T signal MsKT cause an interrupt signal I N based on the timing signal T to be sent to the line 7!14.
TT is derived. As a result, the MPU 14 temporarily suspends the operation currently being executed and executes the interrupt operation (j) of the print programmer.

In other words, the print data signal is on line t'16.
1, and the printer 11 receives this, takes in the print data D, and performs a printing operation.

During this time, M P [114 is the mask T signal M S
Set KT. Therefore, the level of the input terminal T-11 of the interrupt request circuit 16 changes, and the level of the line 11.l is fixed at the inactive level of the interrupt signal INTT.

Thereafter, the MPU 14 prohibits the generation of the interrupt signal INTT, and at the same time removes the interrupt signal 10 times and performs the same operation. This prohibition period continues for a predetermined period of time, and Progress f★Mask signal M
Reset SKT and enable generation of interrupt signal INTT. Therefore, all noise signals that enter during this prohibition period are removed, and a situation that interferes with the operation of the printer 11 is completely prevented.

FIG. 2 is a flowchart showing the operation of this embodiment. This will be explained with reference to FIG. When the printing operation starts, in step r+l, the interrupt request circuit 16 determines whether an edge is detected in the timing signal T output from the printer 11. If an edge is detected, the interrupt request signal INTT is issued. The request circuit 16 is given to the MPU 14.
The timing signal T is read twice by the logic determining circuit 15. As a result of the second reading, if the level of the timing signal T is determined, the process advances to step rI3, and MPU
14 outputs a mask T signal MSKT, whereby the interrupt request signal INT is inhibited by the interrupt request circuit 16. In step n4, the print data D is output to the printer 11, the printer 11 is driven, and a printing operation is performed. During this time, MPUL4 outputs the mask T signal M.
SKT is being counted.

When it is determined at step 5 that the time width of the mask T signal has reached the specified time, the MPU 14 resets the mask T signal M S K T at step rI6.

As a result, input of the timing signal T is permitted from step r16 onwards, and at step r+7, the entire printing program is executed, and it is determined whether the printing operation is finished. If the printing has not been completed, the process returns to step 7 and r11, and printing continues in the same manner.

Although the operations of the logic judgment circuit 15 and the interrupt request circuit 16 in the above explanation are all realized by the program of the MPU 14, that is, by the software software 5, it is important to understand the operation of this embodiment. Therefore, if this is expressed by the hardware configuration, it is equivalently shown in, for example, FIG. 3 or FIG. 4.

FIG. 3 is an example of the hardware configuration of the logic decision circuit 15, in which the second timing signal T2 of the waveform shaping j branch is shown in FIG.
is sequentially transferred through the multiple stages of latch circuits LL, L2, .
0 time n at which the timing signal Trl delayed by
is, for example, 10 μs. By inputting this timing signal To with a delay of time II and the second timing T2 with no time delay on the - side to the NAND gate A, it is possible to obtain the third timing signal T by the coincidence of the two. can. That is, the timing signal T is determined, and the influence of noise signals during the time n (for example, 10 μs) can be removed.

Similar means are also expressed in item 4121. FIG. 4 shows the operation of the latch circuits L1 to Ln described above realized by a shift register circuit S, in which the second timing signal T input to the input terminal of the shift register circuit S is shown in FIG.
2 is sequentially shifted by the clock signal CK, and the timing signal Trl delayed by the time n is derived from the final output terminal Q as in FIG. If you AND with T2,
A desired third timing signal T can be obtained.

Effects of the Invention As described above, the control signal detection method according to the present invention determines the control signal by detecting the edges of the waveform of the control signal input at a predetermined period. Next, a desired operation based on the control signal is executed for a certain period of time, and in synchronization with the control signal, further input to the control signal input terminal is prohibited during the period, thereby preventing noise and its effects. do.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the electrical configuration of a control signal detection method according to an embodiment of the present invention, FIG. FIG. 4 is an equivalent circuit diagram showing another example of the hardware configuration, and FIG. 5I2I is an equivalent circuit diagram showing a hardware configuration to explain the determination circuit. Block diagram shown, No. 6I2
I is a time chart showing the movement. DESCRIPTION OF SYMBOLS 11... Printer, 13... Control unit, 14... Central processing unit (MPU>, 15... Logic judgment circuit, 16
... Interrupt request circuit agent Patent attorney Kei Saikyo Figure 1] 3 Chain 4:

Claims (1)

[Claims] Edge detection means for detecting at least either a falling edge or a rising edge of a control signal input at a predetermined first time period; a signal determining means for determining the level of the control signal by detecting the control signal again after two hours;
A method for detecting a control signal, comprising: prohibiting means for prohibiting input of the control signal within the period period over time.