CN204481799U - A kind of keyboard scanning circuit - Google Patents
A kind of keyboard scanning circuit Download PDFInfo
- Publication number
- CN204481799U CN204481799U CN201520166258.9U CN201520166258U CN204481799U CN 204481799 U CN204481799 U CN 204481799U CN 201520166258 U CN201520166258 U CN 201520166258U CN 204481799 U CN204481799 U CN 204481799U
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- Prior art keywords
- keyboard
- button
- circuit
- scan
- chip
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Abstract
The utility model relates to a kind of keyboard scanning circuit, the push-button array comprising key scan chip and be made up of the button be electrically connected between every two the keyboard scan I/O ports of described key scan chip or push-button array subset, it is characterized in that, also comprise the positive source/negative pole of described key scan chip and the button be electrically connected between any one keyboard scan IO.The keyboard I/O pin number that this circuit utilizes chip limited, realizes the circuit of more buttons, greatly reduces circuit cost, improves benefit in conjunction with positive source/negative pole.
Description
Technical field
The utility model relates to integrated circuit (IC) chip, is specifically related to a kind of keyboard scanning circuit of extended keyboard quantity.
Background technology
Keyboard I/O port in a limiting case, low cost can realize more external key board, because reduce keyboard I/O port just mean the cost that can reduce chip and encapsulation.The circuit design of the multiple button of existing band is usually as remote controller scheme, and wherein in integrated circuit (IC) chip, keyboard I/O port has 6, but usually can realize at most 21 buttons; Accordingly, if will how external button again, more keyboard I/O port need be designed;
Closest to scheme of the present utility model as Fig. 1, the program make use of 6 keyboard I/O ports and realizes 21 external buttons; When needs more external connection keyboard time, the I/O port quantity of keyboard must be improved;
The design of common keyboard I/O port, be all design the pull-up circuit of small area analysis and the drop-down output of big current to realize common keyboard scanning circuit, and in this process, if utilize this circuit design to go to drive keyboard I/O port to connect the button of positive source, then the positive source of circuit can be caused to be connected with the short circuit of keyboard I/O port due to button, and when the I/O port output big current of keyboard is drop-down time, electric current can be caused excessive, cause the exception of whole circuit, if such as with battery pas power source, then may export 0V due to positive source and I/O port thus form short circuit current, the decline of powered battery not enough supply voltage is caused to cause other circuit also to work abnormal, so common keyboard I/O port circuit cannot support that keyboard I/O port is connected to form button by the positive source of external button and circuit.
Utility model content
The utility model technical issues that need to address how to provide a kind of keyboard scanning circuit, and keyboard I/O port in a limiting case, low cost can realize more external key board.
Above-mentioned technical problem of the present utility model solves like this: build a kind of keyboard scanning circuit, the push-button array comprising key scan chip and be made up of the button be electrically connected between every two the keyboard scan I/O ports of described key scan chip or push-button array subset, it is characterized in that, also comprise the positive source of described key scan chip and the corresponding button be electrically connected between each keyboard scan IO or corresponding sub-set of keys.
According to the keyboard scanning circuit that the utility model provides, also comprise the power cathode of described key scan chip and the corresponding button be electrically connected between each keyboard scan I/O port or corresponding sub-set of keys.
According to the keyboard scanning circuit that the utility model provides, described keyboard scan I/O port comprises small area analysis pull-up unit and the big current drop-down unit of coupling positive source.
The keyboard scanning circuit that the utility model provides, be particularly useful for the remote controller chip being with extended keyboard, adopt full embedding structure, comparatively prior art has the following advantages: only need 6 keyboard I/O ports, then can realize 27 buttons; If same increases keyboard I/O port, then can realize more button, if such as 7 keyboard I/O ports, then can realize 35 buttons; The rest may be inferred.
Accompanying drawing explanation
Further the utility model is described in detail below in conjunction with the drawings and specific embodiments.
Fig. 1 is traditional remote controller application circuit schematic diagram;
Fig. 2 is the remote control circuitry schematic diagram of the utility model circuit;
Fig. 3 is keyboard scan chip I/O port electrical block diagram in Fig. 2.
Embodiment
As shown in Figure 2, the utility model scheme make use of 6 keyboard I/O ports and realizes 27 external buttons; Wherein port one is power cathode, and port 2-6 is keyboard I/O port, and port 8 is positive sources.
As shown in Figure 3, the utility model keyboard I/O port connection positive source and power cathode are to produce effective button; When design the utility model keyboard I/O port circuit, design the pull-up circuit of more small area analysis, simultaneously design big current drop-down in, by the size of design con-trol electric current, the pull-down circuit of about about the 10 times pull-up currents of usual design, thus making when keyboard connects power supply, electric current is also within the scope that can bear; The PMOS of concrete circuit design pull-up circuit approximately the electric current of pull-up can be about 10 ~ 60uA; Big current pull-down circuit then designs 100 ~ 600uA; In this current range, then can realize normally expanding keypress function
The foregoing is only preferred embodiment of the present utility model, all equalizations done according to the utility model right change and modify, and all should belong to the covering scope of the utility model claim.
Claims (3)
1. a keyboard scanning circuit, the push-button array comprising key scan chip and be made up of the button be electrically connected between every two the keyboard scan I/O ports of described key scan chip or push-button array subset, it is characterized in that, also comprise the positive source of described key scan chip and the corresponding button be electrically connected between each keyboard scan IO or corresponding sub-set of keys.
2. keyboard scanning circuit according to claim 1, is characterized in that, also comprise the power cathode of described key scan chip and the corresponding button be electrically connected between each keyboard scan I/O port or corresponding sub-set of keys.
3. keyboard scanning circuit according to any one of claim 1-2, is characterized in that, described keyboard scan I/O port comprises small area analysis pull-up unit and the big current drop-down unit of coupling positive source.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520166258.9U CN204481799U (en) | 2015-03-24 | 2015-03-24 | A kind of keyboard scanning circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520166258.9U CN204481799U (en) | 2015-03-24 | 2015-03-24 | A kind of keyboard scanning circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204481799U true CN204481799U (en) | 2015-07-15 |
Family
ID=53637570
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201520166258.9U Expired - Fee Related CN204481799U (en) | 2015-03-24 | 2015-03-24 | A kind of keyboard scanning circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN204481799U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108768406A (en) * | 2018-07-03 | 2018-11-06 | 珠海进田电子科技有限公司 | A kind of New Type of Chip Microcomputer key scanning circuit |
-
2015
- 2015-03-24 CN CN201520166258.9U patent/CN204481799U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108768406A (en) * | 2018-07-03 | 2018-11-06 | 珠海进田电子科技有限公司 | A kind of New Type of Chip Microcomputer key scanning circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20180612 Address after: 518000 room 213, 11 Zhongxing Industrial Town, Chuang Road, Nanshan District, Shenzhen, Guangdong Patentee after: Shenzhen Tianyi Xin Technology Co., Ltd. Address before: 518065 10E, 45 Jiali building, Shekou Road, Shekou, Nanshan District, Shenzhen, Guangdong Patentee before: Ming Xin Microtronics A/S of Shenzhen |
|
| TR01 | Transfer of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150715 Termination date: 20200324 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |