GB2169118A

GB2169118A - Digit strobe designation

Info

Publication number: GB2169118A
Application number: GB08531675A
Authority: GB
Inventors: Shigeru Shindoh
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 1984-12-28
Filing date: 1985-12-23
Publication date: 1986-07-02
Also published as: DE3545374A1; JPS61156422A; GB8531675D0

Abstract

A digit strobe designation method comprises the steps of dividing strobe lines into a plurality of groups G1,G2,G3 of strobe lines, supplying simultaneously a group strobe signal to all the strobe lines in at least one of the groups of the strobe lines, and supplying individual strobe signals at different timings to the strobe lines in a specific group selected by supplying the group strobe signal. <IMAGE>

Description

SPECIFICATION Digit strobe designation method Background of the Invention The present invention relates to an improved method of designating digit strobes for use in key input devices.

Fig. 4 is the wiring diagram of a key input device employing a related digit strobe designation method of the related art. Fig. 5 is the flow chart of a control program for the key input device in Fig. 4.

In Fig. 4, (11) is a key matrix of the key input device and (12) is a buffer for designating digit strobes of the key matrix (11). The buffer (12) has an OR gate (13) for each digit.

A simultaneous designation signal C is input to each OR gate (13), (13). . Signals from address registers BL are also input for each digit into each OR gate (13), (13). . In the related art, as shown in Fig. 4, key search is conducted by strobe signals D,~D7 and input signals KL1KL4.

Digit strobes are designated in the procedure shown in Fig. 5. In the beginning, all digit strobes are designated by Ccl. If KL=0, it is judged that no key has been depressed.

If KL+0 it is judged that a certain key has been depressed. Address registers BL0~BL6 are then designated in turn. BL and KL values for KLfO are stored and key search operation ends.

In the related art, as mentioned above, key search operation is started by turning all strobe signals ON. When a key input is detected, strobes are sequentially designated until the operated key is identified. According to the example shown, strobe designation is required two--eight times depending upon the position of an operated key. Accordingly, the key-judging period, from the time a key is depressed to the time the key data is stored, or namely when the key input is actually accepted, varies greatly depending key position.

The average key-judging period is, therefore, long.

Summary of the Invention In view of the foregoing, it is the object of the present invention to provide an improved digit strobe designation method to minimize variations in key-judging or the like processing times as well as shorten average processing time.

Other objects and the further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

To achieve the above objects, according to an embodiment of the present invention, a digit strobe designation circuit comprises a plurality of groups of strobe lines, group strobe signal supply means for simultanesously supplying a group strobe signal to all the stobe lines in at least one of the groups of the strobe lines, and single line strobe signal supply means for supplying individual strobe signals at different timings to the strobe lines in a specific group selected by the group strobe signal supply means.

To achieve the above objects, according to another embodiment of the present invention, a digit strobe designation method comprises the steps of dividing strobe lines into a plurality of groups of strobe lines, supplying for simultaneously a group strobe signal to all the stobe lines in at least one of the groups of the strobe lines, and supplying individual strobe signals at different timings to the strobe lines in a specific group selected by supplying the group strobe signal.

According to the present invention, key search operation is conducted simultaneously for a plurality of strobe lines in a group. Time required for strobe line processing is therefore reduced, variation in the processing time among different strobe lines minimized, and average time required for key-judging shortened.

Brief Description of the Drawings The present invention will better understood from the detailed description and accompanying drawings given hereinafter, which are given by way of illustration only and thus are not limitative of the present invention in which: Figure 1 is the wiring diagram of the essential part of a key input device to which the present invention is applied, Figure 2 is the operation flow chart of the key input device of Fig. 1, Figure 3 is the block diagram of an example of LSI, Figure 4 is the wiring diagram of the essential part of the conventional key input device, and Figure 5 is the operation flow chart of the conventional key input device in Fig. 4.

Detailed Description of the Invention An example of the present invention will be described below with reference to the accompanying drawings.

In this example, the invention is applied to a method of key search via digit strobe designation signals output to outside an LSI. Fig. 1 shows the relationship between buffer and key matrix, Fig. 2 is the flow chart, and Fig. 3 is the block diagram of an LSI example.

The present invention may be applied to methods other than the key search method.

In Fig. 3, ROM is a read-only-memory for storing program instructions, Inst. Decoder is an instruction decorder, and PU and PL are program counters for ROM. SU, SL, RU and RL are stack registers for sub-routine operation, RAM is a random-access-memory, BM and BL are address registers for RAM, DEC is a decoder for decoding address register content and, BUF is an output buffer through which strobe signal is output according to address register value. Acc is an accumulator. A carry flag for a buffer, through which strobe signal is output, is set according to arithmetic operation for the accumulator or according to carry-set instruction in the program. KH and KL are input buffers. The KL buffer is used as an input terminal for key data.

In Fig. 1, (1) is a key matrix for an input device and (2) is the output buffer BUF of Fig.

3 through which strobe signals Do~Dt2 are output. The strobe lines in buffer (2) are divided into three groups: the first group G1 corresponds to the RAM address signal BL=13, the second group G2 corresponds to BL=14, and the third group G3 corresponds to BL=15. As group strobe signals, signal BL=13 is given through OR gates (3) to the strobe lines in group G1, signal BL=14 to the strobe lines in group G2, and signal BL=15 to the strobe lines in group G3. Further, signals BL--0BL= 11 are given to each strobe line as individual strobe signals.

Operation of the present invention will be described with reference to the flow chart in Fig. 2, on the assumption that a key at the intersection of D5 and KL1, as indicated by a circle on the key matrix (1), is depressed.

In the beginning, strobe lines of the first group G1 are simultaneously designated by By 13 so that strobe signals D1~D3 are supplied to the key matrix. Since KL=0 and BL+15, BL gains "1" ' (BL~BL+1) to become "14" (BL= 14). Thus, after the three strobe lines of group G1 are simultaneously processed, strobe lines D4~D6 are simultaneously designated next. Since KL0, the program proceeds to the right in Fig. 2 and judges whether BL=13.Since the result is "NO", the program judges whether BL=14. This time the result is "YES", and the program proceeds to the right in Fig. 2 and designates the strobe lines in the second group G2 from BL=3 in turn. In this example, KL0 when BL=4. The values for BL and KL for KL0 are stored and key search operation ends.

In this example, the key search operation is conducted using the same number of strobe signals (D1~D7) and input signals (KL1~KL4) as in the related art shown in Fig. 4. In the present example, seven strobe lines are divided into two groups of three with the seventh strobe line belonging to the third group. Accordingly, the present invention involves from two to five designations of strobes whereas the related art involves from two to eight strobe designations. That is, the difference between the maximum and minimum number of designations is reduced from six in the related art to three in the present invention. As a result, variation in the time required for key search is minimized, and the average number of designations decreases from 5 to 3.57.

The average time required for key search is accordingly reduced.

According to the present invention, as evident from the above description, strobe lines are divided into a plurality of groups, and group strobe signals are simultaneously given to all the strobe lines in the first group, then to all in the second and third groups in turn.

Individual strobe signals are then given sequentially to the strobe lines in a particular group. Compared with the related art, in which strobe signals are supplied sequentially to all strobe lines, variations in processing time are smaller, average processing time is shorter, operability of equipment to which the present invention is applied is higher, and processing speed is faster.

As described above, a digit strobe designation method comprises the steps of dividing strobe lines into plurality groups of strobe lines, supplying for simultaneously a group strobe signal to all the stobe lines in at least one of the groups of the strobe lines, and supplying individual strobe signals at different timings to the strobe lines in a specific group selected by supplying the group strobe signal.

Although the number of the groups of the strobe lines is three in the embodiment, the number of the groups may be changed or increased.

While only certain embodiments of the present invention have been described, it will be apparent to those skilied in the art that various changes and modifications may be made therein without departing from the spirit and scope of the present invention as claimed.

Claims

1. A digit strobe designation circuit comprising: a plurality of groups of strobe lines; group strobe signal supply means for simultaneously supplying a group strobe signal to all the stobe lines in at least one of the groups of the strobe lines; and single line strobe signal supply means for supplying individual strobe signals at different timings to the strobe lines in a specific group selected by the group strobe signal supply means.

2. A digit strobe designation method comprising the steps of: dividing strobe lines into a plurality of groups of strobe lines; supplying for simultaneously a group strobe signal to all the stobe lines in at least one of the groups of the strobe lines; and supplying individual strobe signals at differ ent timings to the strobe lines in a specific group selected by supplying the group strobe signal.

3. A strobe circuit having a plurality of strobe lines to which strobe signals can be applied to test the state of devices connected to the strobe lines, the circuit having means to apply simultaneously a strobe signal to a plurality but not all of the said strobe lines, and means to supply a strobe signal to the strobe lines of the said plurality of different times from each other.

4. A strobe circuit substantially as herein described with reference to Figs. 1 to 3 of the accompanying drawings.