JPH048811B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) This invention is directed to a microcomputer, particularly a built-in display controller that sequentially scans a plurality of key groups using segment signals applied to an external display device and detects the presence or absence of data input. Regarding microcomputers.

(Prior Art) In a microcomputer system having an external display device composed of a light emitting diode or the like and a keyboard consisting of a plurality of key groups, the microcomputer is capable of displaying each digit of the external display device consisting of a plurality of digits. It has a digit signal generation circuit that outputs a digit signal, and a segment signal generation circuit that specifies the segment that should be emitted from among the multiple segments that make up each digit, for example, the 8 segments from the digit with a decimal point. During display, segment signals were output while changing the digit signals sequentially and synchronizing with the digit signals, causing the light emitting diodes to emit light. In addition, in such a microcomputer, segment signals are also used for scanning the keyboard, and when any key is pressed and a scanning signal is applied to the input terminal of the microcomputer, the microcomputer can detect the output timing of the scanning signal and the scanning signal. Software identifies the input terminal to which the signal is applied and the key pressed to identify the input data.

Therefore, although a microcomputer that can use the segment signal as a key scanning signal can reduce the number of terminals required for the microcomputer, it is difficult to synchronize the output timing of the digit signal with the software, which overcomes the drawbacks of the conventional technology. In order to solve this problem, the applicant of the present application proposed in Japanese Patent Application No. 59-126103 that the timing for using segment signals for key scanning is separated from the timing for applying segment signals to each digit of an external display device, thereby overcoming the difficulties of the prior art. And so.

That is, in Japanese Patent Application No. 59-126103, the digit signal generating means has more time slots than the number of digits of the external display device, and in the time slots corresponding to each digit, segment signals are used to prevent flickering of the external display device. In the remaining time slots, key scanning is performed using segment signals, internal interrupt signals are generated, and data input by keys is determined by software.

(Problems to be Solved by the Invention) In the above-mentioned prior invention of the present applicant, an interrupt signal was generated at a specific time slot and the input data was determined by software. When an interrupt with a higher priority than an interrupt for determination occurs, the input data is determined after the processing based on the interrupt is completed, and at the time of the determination,
If the key scanning period using the segment signal has already ended, there is a problem in that accurate determination cannot be expected.

(Means for Solving the Problems and Their Effects) In view of the above-mentioned difficulties of the prior art and the problems of the prior invention, the present invention generates time slots in the first output means that are larger in number than the number of digits of the external display means. , generating an interrupt in at least one of the time slots, setting a flag means for the duration of the time slot, and a data determining means determining input data based on the presence or absence of a key used for data input. Before doing so, the flag determining means first determines whether or not the flag means is set. If the result of such determination is affirmative, the data determining means determines the input data. On the other hand, if processing is performed based on another interrupt that has priority over the interrupt, the flag determining means sets the flag anew. If the result of the determination is positive, the process immediately proceeds to determine the input data; however, if the result of the determination is negative, the data determination means does not determine the input data. The gist is:

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention. First, the configuration will be explained. Reference numeral 1 indicates a microcomputer, and the microcomputer 1 is composed of arithmetic and logic means (not shown). A digit signal generation circuit 3 that decodes the supplied digit information I ₁ and outputs a digit signal S ₁ to the display 2, and a digit signal generation circuit 3 that decodes the segment information I ₂ also supplied from the arithmetic logic means and outputs a segment signal S ₂ . The segment signal generating circuit 4 has a segment signal generating circuit 4 for generating a segment signal.

The display 2 can display m-digit numbers with a decimal point, each digit consisting of 8 segments, and each segment is composed of a light emitting diode.

The segment signal generation circuit 4 is also connected to a display 5 consisting of a group of eight keys, and since the digit signal generation circuit 3 generates m+1 time slots in one frame, at the m+1th time slot, , segment signal _S2 is applied to the display 5 as a key scanning signal _S3 .
This display 5 applies a key detection signal S ₄ to the input port 6 of the microcomputer 1 when there is a key pressed for data input in the scanned key group. The key detection signal S ₄ applied to the input port 6 is combined with the key scanning signal S ₃ and discriminated by software serving as data discrimination means to identify which key has been pressed.

The aforementioned microcomputer 1 includes an interrupt control circuit 7 serving as an interrupt means for outputting an interrupt signal _S5 at the m+1th time slot, and a flag set signal _S6 which is set during the duration of the m+1th time slot. It has a flag circuit 8 as a flag means for outputting the flag set signal _S6 .
is determined by software as a flag determining means.

Next, the operation of the above embodiment will be explained with reference to the time chart of FIG. 2 as follows. First, when the display data to be displayed in each digit of the display 2 is determined as a result of calculation by the arithmetic logic circuit, digit information I ₁ and segment information I ₂ are transferred to the digit signal generation circuit 3 and the segment signal generation circuit for each digit. 4 and 4 are sequentially supplied. As a result, the digit signal generation circuit 3
are time slots T ₁ , T ₂ , which specify each digit sequentially.
..., T _n+1 is generated, and the segment signal generation circuit 4
outputs a segment signal _S2 in synchronization with time slots T1 to _T1 . Therefore, display 2
For each digit, the segment specified by the segment signal _S2 lights up, and the display data becomes visible.

Next, the digit signal generation circuit 3 generates the time slot.
When T _n+1 is generated, the segment signal generation circuit 4 applies the segment signal S ₂ outputted based on the segment information I ₂ to the keyboard 5 as a key scanning signal S ₃ . At the same time, the interrupt control circuit 7 outputs an interrupt signal _S5 , and the flag circuit 6 is set to output a flag set signal _S6 . Therefore, an interrupt occurs based on the interrupt signal _S5 , and the software first determines whether the flag set signal _S6 is present or not, and if the determination result is positive, then input data is determined. On the other hand, if another interrupt with a higher priority occurs before or after the interrupt occurs based on the interrupt signal _S5 , processing based on the other interrupt is performed first, and then the interrupt signal _S5 is generated. Basic processing is performed. That is, after the processing based on other interrupts is completed, the presence or absence of the flag set signal _S6 is first determined, and if the determination result is affirmative, the process proceeds to input data determination; however, if the determination result is negative, input data determination is not performed. The input data is determined in the next and subsequent frames.

(Effects) As explained above, according to the present invention,
A flag means is set only during the duration of the time slot assigned to the scanning of the key group, and it is determined whether or not the flag means is set, and a data determination means is input only when the flag means is set. Even if an interrupt with a higher priority than the input data determination occurs before or after the key group scan starts, the input data is determined only while the key group is being scanned. It is possible to obtain the effect that data is accurately discriminated.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a time chart of FIG. 1. 2... External display means (display), 3...
First output means (digit signal generation circuit), 4... Second output means (segment signal generation circuit), 5... External data input means (keyboard), 7... Interrupt means (interrupt control circuit), 8 ...Flag means (flag circuit), _T1 to _Tn+1 ...Time slot, _S1 ...Digit signal, _S2 ...Segment signal, _S3 ...Key scanning signal.

Claims (1)

[Claims] 1. A first output means for outputting a digit signal that enables sequential data display of each of the plurality of digits on a multi-digit external display means each consisting of a plurality of segments, and a digit whose data can be displayed by the digit signal. Outputs a segment signal for specifying a segment to be used for data display among the segments, and uses the segment signal as a key scanning signal to sequentially select each key group of the external data input means, which consists of key groups equal to or less than the number of segments constituting each digit. A display controller built-in microcomputer includes a second output means for scanning to detect the presence or absence of a key used for data input, and a data discrimination means for discriminating input data based on the presence or absence of a key used for data input. In the computer, interrupt means generates a number of time slots in the first output means that are larger in number than the number of digits of the external display means, and generates an interrupt in at least one of the time slots, and a time slot in which the interrupt occurs. a flag means that is set only during the duration of the interruption; and a flag means that determines whether or not the flag means is set due to the occurrence of the interrupt, and determines the data input to the data determination means only when the flag means is set. A microcomputer with a built-in display controller, further comprising a flag discrimination means that allows the above.