JPS6461813A - Key matrix switching circuit - Google Patents
Key matrix switching circuitInfo
- Publication number
- JPS6461813A JPS6461813A JP62219405A JP21940587A JPS6461813A JP S6461813 A JPS6461813 A JP S6461813A JP 62219405 A JP62219405 A JP 62219405A JP 21940587 A JP21940587 A JP 21940587A JP S6461813 A JPS6461813 A JP S6461813A
- Authority
- JP
- Japan
- Prior art keywords
- key
- interruption
- inputs
- input
- sources
- Prior art date
- 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.)
- Pending
Links
Abstract
PURPOSE:To eliminate the key scanning actions in a key input holding state by producing an interruption request when a key input signal has a change and inhibiting the change of the key scanning signal when all key matrix switches are kept turned off. CONSTITUTION:The key sources 3-6 are kept at high levels in a key input holding state. When all key switches are key turned off, the key inputs 31-34 are set at low levels by the pull-down resistances 27-30 with the key sources and the key inputs kept static. At the same time, a key input latch 36 and its input are also static so that no interruption is produced. When one of key switches is turned on, one of inputs 31-34 is set at a high level. Then an interruption generating circuit 35 activates an interruption request signal line 37 and applies an interruption to a CPU. The CPU judges the priority degrees and sets successively the sources 3-6 at high levels when the due conditions are satisfied to latch the states of inputs 31-34 via a latch circuit 36. These latches states are read via an input data bus 38. Thus the key scanning actions can be eliminated in a key input holding state.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62219405A JPS6461813A (en) | 1987-09-01 | 1987-09-01 | Key matrix switching circuit |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62219405A JPS6461813A (en) | 1987-09-01 | 1987-09-01 | Key matrix switching circuit |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS6461813A true JPS6461813A (en) | 1989-03-08 |
Family
ID=16734892
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP62219405A Pending JPS6461813A (en) | 1987-09-01 | 1987-09-01 | Key matrix switching circuit |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6461813A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0421019A (en) * | 1990-05-14 | 1992-01-24 | Tamura Electric Works Ltd | Key detecting method |
JPH0540928U (en) * | 1991-10-25 | 1993-06-01 | 株式会社東芝 | Key input detection device |
JP2011164728A (en) * | 2010-02-05 | 2011-08-25 | Yokogawa Electric Corp | Touch panel device |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5250628A (en) * | 1975-10-22 | 1977-04-22 | Fujitsu Ltd | Key input reading system |
-
1987
- 1987-09-01 JP JP62219405A patent/JPS6461813A/en active Pending
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5250628A (en) * | 1975-10-22 | 1977-04-22 | Fujitsu Ltd | Key input reading system |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0421019A (en) * | 1990-05-14 | 1992-01-24 | Tamura Electric Works Ltd | Key detecting method |
JPH0540928U (en) * | 1991-10-25 | 1993-06-01 | 株式会社東芝 | Key input detection device |
JP2011164728A (en) * | 2010-02-05 | 2011-08-25 | Yokogawa Electric Corp | Touch panel device |
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