CN102436309A - Keyboard circuit - Google Patents
Keyboard circuit Download PDFInfo
- Publication number
- CN102436309A CN102436309A CN2011104343168A CN201110434316A CN102436309A CN 102436309 A CN102436309 A CN 102436309A CN 2011104343168 A CN2011104343168 A CN 2011104343168A CN 201110434316 A CN201110434316 A CN 201110434316A CN 102436309 A CN102436309 A CN 102436309A
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- circuit
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- keyboard
- keyboard circuit
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- 230000011664 signaling Effects 0.000 claims description 15
- 238000000034 method Methods 0.000 abstract description 4
- 230000002093 peripheral effect Effects 0.000 abstract 1
- 230000007423 decrease Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- Input From Keyboards Or The Like (AREA)
Abstract
A keyboard circuit belongs to the peripheral field of computers. The method is characterized in that: the keyboard circuit is characterized in that an input enabling control circuit is additionally arranged on the basis of the existing keyboard circuit, the input enabling control circuit comprises two monostable triggers which can trigger and output a short-time pulse signal, the input end of one monostable trigger is connected with the output end of a key signal circuit, the input end of the other monostable trigger is connected with the chip selection signal output end of a central processing unit, and the output ends of the two monostable triggers are respectively connected to the two input ends of an OR gate output circuit. The invention controls the input enable end of the latch through the input enable control circuit and combining the key signal and the chip selection signal, so that the keyboard circuit can prevent the keyboard from losing, simplify the software algorithm and greatly save the resource system.
Description
Technical field
A kind of keyboard circuit belongs to the computer external field.
Background technology
In the embedded board design, often to use keyboard circuit, keyboard driver available query mode or external hardware interrupt mode are obtained the button situation in traditional keyboard input circuit; If driver adopts inquiry mode, because program does not know when keyboard is pressed, in order not lose push button signalling as far as possible; Must adopt regularly and interrupt; Will remove to read No. one time latch at set intervals, and according to read data judge, handle, upgrade keyboard buffer, this method may cause key information to be lost; And the waste resource, calculation of complex.
Summary of the invention
The present invention is exactly a series of problems that exist in the said process in order to solve, and a kind of keyboard circuit easily is provided, and the present invention realizes through following technical scheme:
A kind of keyboard circuit belongs to the computer external field.It is characterized in that: on the basis of existing keyboard circuit, set up input and enable control circuit; Comprising two monostalbe triggers that can trigger and export the short-time pulse signal; The input end of a monostalbe trigger links to each other with the output terminal of push button signalling circuit; The input end of another monostalbe trigger links to each other with the chip selection signal output terminal of central processing unit, and the output terminal of two monostalbe triggers is connected respectively to two input ends of or gate output circuit.
Further, a kind of keyboard circuit, wherein said keyboard circuit comprises a plurality of buttons, and each button is connected to an input end of latch, and signal circuit all can be exported a push button signalling after arbitrary button was pressed.
Further, a kind of keyboard circuit, wherein said latch inside is contained one and is posted the control device, and the hardware keyboards buffer zone as a byte is used to store current key assignments.
Further, a kind of keyboard circuit, each output terminal of wherein said latch is used to export the current key assignments that latchs, and its output enable end links to each other with the chip selection signal output terminal of central processing unit.
Further; A kind of keyboard circuit, wherein said push button signalling circuit output low level push button signalling when arbitrary button is pressed, monostalbe trigger output high pulse signal; The input Enable Pin of latch is accepted high level, and the output enable termination receives low level.
Embodiment
A kind of keyboard circuit belongs to the computer external field.It is characterized in that: on the basis of existing keyboard circuit, set up input and enable control circuit; Comprising two monostalbe triggers that can trigger and export the short-time pulse signal; The input end of a monostalbe trigger links to each other with the output terminal of push button signalling circuit; The input end of another monostalbe trigger links to each other with the chip selection signal output terminal of central processing unit, and the output terminal of two monostalbe triggers is connected respectively to two input ends of or gate output circuit.
The present invention in use presses arbitrary key, and push button signalling will become low level by high level, the decline of this signal can trigger one of steady state trigger output in short-term high pulse signal be that the input Enable Pin of latch is effective to latch.Simultaneously, latch can latch current key assignments in internal register, and when this button was released, push button signalling interrupted, and push button signalling reverts to high level, and the key assignments that latchs remains unchanged, up to pressing lower keyboard again.
The input Enable Pin is just can be touched in push button signalling decline and chip selection signal rising only, and the input Enable Pin is effective, and other situation are all invalid.
When driver reads key assignments, can export a low pulse chip selection signal, be connected to latch as the output enable signal of latch, the output terminal of latch is opened between low period, and the current key assignments that latchs is derived, and is sent on the data line.When low pulse chip selection signal rises to along point; Trigger steady state trigger and be touched high impulse chip selection signal of output; Latch latchs current key assignments once more, if button is released then is equivalent to the buffer zone automatic clear at this moment, does not discharge like button; The key assignments that then obtains once more is identical with former key assignments, is equivalent to buffer zone and keeps former key assignments.Among the present invention, to get speed very fast with emptying buffer zone to latch key assignments, and the back key assignments that pushes button can be latched in the buffer zone in a short period of time automatically, can not cause key assignments to lose.
The present invention uses two steady state triggers; Control lock storage switch when chip selection signal descends and rise respectively; These two steady state triggers are connected to two input ends of or gate output circuit simultaneously, comprise two diodes that link to each other with the steady state trigger output terminal respectively, two resistance and a traditional OR circuit in the OR circuit.The negative pole of two diodes interconnects the back resistance grounded, is connected to the input Enable Pin of latch, and the output terminal of OR circuit also is connected to the input Enable Pin of latch.The input Enable Pin of latch is not that traditional direct quilt is drawn high, and controls but receive input to enable control circuit.
The present invention improves on the basis of keypad circuit; Increase an input and enabled control circuit; And changed the method that connects of some of them circuit accordingly, and enable control circuit and combine push button signalling and input Enable Pin that chip selection signal comes the control lock storage through input, make keyboard circuit after improving can prevent that button from losing; Can simplify software algorithm greatly again, save system resource.
Claims (5)
1. keyboard circuit; Belong to the computer external field; It is characterized in that: on the basis of existing keyboard circuit, set up input and enable control circuit; Comprising two monostalbe triggers that can trigger and export the short-time pulse signal; The input end of a monostalbe trigger links to each other with the output terminal of push button signalling circuit, and the input end of another monostalbe trigger links to each other with the chip selection signal output terminal of central processing unit, and the output terminal of two monostalbe triggers is connected respectively to two input ends of or gate output circuit.
2. a kind of keyboard circuit according to claim 1 is characterized in that: described keyboard circuit comprises a plurality of buttons, and each button is connected to an input end of latch, and signal circuit all can be exported a push button signalling after arbitrary button was pressed.
3. a kind of keyboard circuit according to claim 2 is characterized in that: described latch inside is contained one and is posted the control device, and the hardware keyboards buffer zone as a byte is used to store current key assignments.
4. a kind of keyboard circuit according to claim 2 is characterized in that: each output terminal of described latch is used to export the current key assignments that latchs, and its output enable end links to each other with the chip selection signal output terminal of central processing unit.
5. a kind of keyboard circuit according to claim 2; It is characterized in that: described push button signalling circuit output low level push button signalling when arbitrary button is pressed; Monostalbe trigger output high pulse signal, the input Enable Pin of latch is accepted high level, and the output enable termination receives low level.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011104343168A CN102436309A (en) | 2011-12-22 | 2011-12-22 | Keyboard circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011104343168A CN102436309A (en) | 2011-12-22 | 2011-12-22 | Keyboard circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN102436309A true CN102436309A (en) | 2012-05-02 |
Family
ID=45984405
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011104343168A Pending CN102436309A (en) | 2011-12-22 | 2011-12-22 | Keyboard circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN102436309A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107340874A (en) * | 2016-04-29 | 2017-11-10 | 姚秉洋 | Touch control type keyboard |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1815416A (en) * | 2005-02-01 | 2006-08-09 | 艾默生网络能源系统有限公司 | Keyboard circuit |
| CN101853075A (en) * | 2010-04-27 | 2010-10-06 | 上海坤联电子科技有限公司 | Multiplexed-output multifunctional keyboard |
-
2011
- 2011-12-22 CN CN2011104343168A patent/CN102436309A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1815416A (en) * | 2005-02-01 | 2006-08-09 | 艾默生网络能源系统有限公司 | Keyboard circuit |
| CN101853075A (en) * | 2010-04-27 | 2010-10-06 | 上海坤联电子科技有限公司 | Multiplexed-output multifunctional keyboard |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107340874A (en) * | 2016-04-29 | 2017-11-10 | 姚秉洋 | Touch control type keyboard |
| CN107340874B (en) * | 2016-04-29 | 2021-04-06 | 姚秉洋 | Touch control type keyboard |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C02 | Deemed withdrawal of patent application after publication (patent law 2001) | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20120502 |