CN101013896A

CN101013896A - Keyboard scanning circuit and scanning method thereof

Info

Publication number: CN101013896A
Application number: CN 200610063432
Authority: CN
Inventors: 金红志
Original assignee: SHENZHEN CHINALC SEMICONDUCTOR CO Ltd
Current assignee: SHENZHEN CHINALC SEMICONDUCTOR CO Ltd
Priority date: 2006-11-01
Filing date: 2006-11-01
Publication date: 2007-08-08
Anticipated expiration: 2026-11-01
Also published as: CN100546202C

Abstract

The invention discloses one key scanning circuit and its circuit scanning method, wherein, the scanning circuit comprises I/O cross array, key output unit and key scanning circuit; each key scanning line output is as I/O cross array input wire and output wires. The scanning method is to judge effective key operation when the key output line unit has two level jumps. The invention forms NX(N-1)/2 keys for the N pieces of IO scanning holes.

Description

Keyboard scanning circuit and scan method thereof

Technical field

The present invention relates to the scanning circuit and the scan method of a kind of keyboard scanning circuit and scan method, particularly a kind of matrix type structure.

Background technology

Existing keyboard scanning circuit adopts the matrix structure form more, every input, output line use an IO scanning mouth, scan matrix for X*Y, be X scanning output line, Y scanning incoming line, the output scanning signal is to Y different scanning incoming lines in order for X scanning output line, and the internal judgment circuit sends different sign indicating numbers according to the different output lines and the combination of incoming line.As chip 3010,64 keys need 16 IO scanning mouths, 8 are used for incoming line, other 8 are used for output line, and 7461,32 keys of chip need 12 IO mouths, 8 are used for incoming line, other 4 are used for output line etc., and this scan mode is faced with very big cost pressure in the so fierce market of this competition today, therefore need go to seek a kind of more cheap scan mode.Along with development of science and technology, the application of the progress in epoch, particularly remote controller more and more widely, the bond number of pressing on the remote controller also gets more and more, but the quality requirement to remote controller is more and more higher, and cost pressure is also increasing, so traditional scan mode can not satisfy requirement cheaply.

Summary of the invention

Number of keys needs a large amount of technical problems that scan mouth for a long time in the prior art in order to solve in the present invention, has proposed a kind of keyboard scanning circuit and scan method thereof of the IO of saving scanning mouth.

The keyboard scanning circuit that the present invention proposes comprises: input and output cross matrix, button output line unit, also comprise the key scan line circuit, every key scan line in this key scan line circuit all comprises the reverser of two serial connections, and each sweep signal DO exports KIO through two corresponding reverser outputs as each key scan line; The output KIO while of each key scan line is as the incoming line and the output line of input and output cross matrix.

Preferably, every button output line in the described button output line unit comprises the NAND gate of a reverser and one two input, together as the input of NAND gate, the output EI of described NAND gate is as the judgement signal of actuation of keys through reverser and corresponding sweep signal DO for each key scan line output KIO.

Preferably, the reverser away from sweep signal DO is to be made of a undersized PMOS pipe and a large-sized NMOS pipe in described each key scan line.

The key scan method that the present invention proposes may further comprise the steps:

1) sweep signal of output low level pulse;

2) monitor the output level saltus step situation of each button output line unit, when having and only having two outputs to produce the level saltus steps on the EI, be judged as effective actuation of keys and take place.

Preferably, two adjacent low level pulses in the step 1) have a time interval.

Preferably, step 2) when having monitored two outputs when producing the level saltus steps, be judged as an actuation of keys and taken place in, button be input, the output line corresponding key of these two output connections.

Technique effect of the present invention is: because each key scan line is simultaneously as incoming line and output line, it is bidirectional interface, different key scan lines can constitute the button point in twos, and the key scan line can only be as incoming line or output line in the prior art, and incoming line corresponding key scan line can only constitute the button point with output line corresponding key scan line combination.Number of keys of the present invention can constitute N * (N 1)/2 buttons for N IO scanning mouth, has increased the quantity of button greatly, has reduced production cost.

Description of drawings

Fig. 1 is key scan line of the present invention and output line circuit diagram thereof;

Fig. 2 is a sweep signal output waveform figure of the present invention;

Fig. 3 is the keyboard scanning circuit figure of 4 IO mouths in the preferred embodiment of the present invention.

Embodiment

Further specify technical scheme of the present invention below in conjunction with accompanying drawing and by specific embodiment.As shown in Figure 1, sweep signal DO (0) is through twice anti-phase back output KIO (0) of two reversers.Output KIO (0) while of key scan line is as the incoming line and the output line of button cross matrix.The output KIO (0) of key scan line imports a NAND gate through behind the reverser with sweep signal DO (0), and its output EI (0) is as the judgement signal of actuation of keys.That reverser away from sweep signal DO in each key scan line is to be made of a undersized PMOS pipe and a large-sized NMOS pipe, and the output of this reverser constitutes output KIO.

As shown in Figure 2, sweep signal DO is the signal that internal circuit produces, and is low level pulse, exports square wave in order.And the output low level pulse of two adjacent sweep signals has certain time interval, handles can for like this sequence circuit of back and bringing great convenience, and can avoid the generation of race hazard.Obtain after oppositely through twice because the output KIO of key scan line is sweep signal DO, so its waveform is identical with the waveform of sweep signal DO.

When the output KIO (0) of key scan line does not link to each other with the output of other key scan line, by the circuit of Fig. 1 as can be known its output EI (0) keep high level always, can the output low level pulse.

As shown in Figure 3, the keyboard scanning circuit with 4 IO mouths is that example specifies scanning circuit of the present invention and method.4 tunnel sweep signal DO (0)-DO (3) is respectively through exporting KIO (0)-KIO (3) in the key scan line circuit 10 behind two reversers.Output KIO (0)-KIO (3) constitutes cross matrix as incoming line and output line simultaneously, and has formed 6 buttons of 1 to 6 on input and output cross matrix 11.Output KIO (0) is through importing a NAND gate with sweep signal DO (0) behind the reverser, and its output EI (0) is as the judgement signal of actuation of keys, and 4 IO scanning mouths have just constituted output EI (0)-EI (3).EI when button is not pressed (0)-EI (3) output keeps high level.

Be pressed to be the concrete scanning process of example explanation with button 1 below.When button 1 is pressed, KIO (0) links to each other with KIO (1), because the pulse of low level pulse ratio DO (1) output low level of DO (0) output early, the pulse of output KIO (1) output low level of the time ratio key scan line of output KIO (0) the output low level pulse of key scan line also early behind the process reverser.When the output KIO (0) of key scan line output low level pulse, this moment, the output KIO (1) of key scan line exported high level, because KIO (0) output low level is drop-down by big NMOS pipe, and KIO (1) exports high level by drawing on the little PMOS pipe, and pull-down capability is better than the ability of drawing, and finally they are drawn as near low level, through after once anti-phase, become high level, and DO this moment (1) is output as high level, so EI (1) is output as low level.Then when DO (1) output low level, same principle, EI (0) exports a low level.The internal logic decision circuitry just knows have key to press according to these two low level signals, and knows when have key to press, and the inner lock storage circuit will latch one group of code.Learning on EI (1) and EI (0) corresponding scanning line KIO (1) and the KIO (0) has button to press, and promptly button 1 is pressed.

Use 4 IO scanning mouths can only constitute 4 buttons for prior art, and the present invention can constitute 6 buttons.If 12 IO scanning mouthful, 36 buttons of multipotency structure of prior art adopt the present invention can construct 66 buttons, and number of keys increases greatly.

What deserves to be explained is, the replacement scheme of a lot of modification to be arranged, for example: export anti-phasely, increase the key scan number of pin, use some equivalent Symbol instead and replace, all belong to equivalent of the present invention based on principle of the present invention.Every key scan pin is two-way; promptly do output usefulness, do input usefulness again, each key scan pin all has sweep signal output; meet top computing formula by bond number and key scan pin, all should be considered as content disclosed in this invention and protection scope of the present invention.

Claims

1. keyboard scanning circuit, comprise: input and output cross matrix (11), button output line unit (12), it is characterized in that, also comprise key scan line circuit (10), every key scan line in this key scan line circuit (10) all comprises the reverser of two serial connections, and each sweep signal D0 exports KIO through two corresponding reverser outputs as each key scan line; The output KIO while of each key scan line is as the incoming line and the output line of input and output cross matrix (11).

2. keyboard scanning circuit according to claim 1, it is characterized in that, every button output line in the described button output line unit (12) comprises the NAND gate of a reverser and one two input, together as the input of NAND gate, the output EI of described NAND gate is as the judgement signal of actuation of keys through reverser and corresponding sweep signal D0 for each key scan line output KIO.

3. keyboard scanning circuit according to claim 1 and 2 is characterized in that, the reverser away from sweep signal D0 in described each key scan line is to be made of a undersized PMOS pipe and a large-sized NMOS pipe.

4. a key scan method is characterized in that, said method comprising the steps of:

1) sweep signal of output low level pulse;

2) the output level saltus step situation of monitoring button output line unit, as and when only having two outputs to produce the level saltus steps, be judged as effective actuation of keys and take place.

5. key scan method according to claim 4 is characterized in that, two adjacent low level pulses in the described step 1) have a time interval.

6. according to claim 4 or 5 described key scan methods, it is characterized in that, described step 2) two outputs have been monitored when producing the level saltus steps when button output line circuit (12) in, be judged as an actuation of keys and taken place, button is these two input, output line corresponding key that output connects.