Method and circuit for detecting press key

Abstract

The invention discloses a method for detecting a press key. The method comprises the following steps: setting a circuit for detecting the press key; detecting whether the press key is pressed down; carrying out voltage A / D conversion; judging which press key is pressed down concretely; and waiting for the press keys to be pressed down next time. The invention also discloses the circuit for detecting the press key, which comprises a plurality of divider resistances with different resistance values and a singlechip, wherein one end of each divider resistance is respectively and correspondingly connected with one end of each press key; the other ends of a plurality of press keys are earthed; the other ends of a plurality of divider resistances are connected together to form a voltage signal detecting end; the voltage signal detecting end is connected to a power supply after passing through another resistance; and a multiplexed IO port of the singlechip, which serves as both an interrupt input IO port and an A / D conversion input port, is connected to the voltage signal detecting end. The method and the circuit for detecting the press key are characterized by capability of realizing scanning dozens of press keys only by utilizing one or two IO ports of the singlechip and have the advantages of few occupied IO ports of the singlechip, low cost of the singlechip and the like.

Description

[Technical Field] [0001] The invention relates to a button detection method and a button detection circuit. [Background technique] [0002] There are many home appliances on the market with key input, most of which are controlled by a single-chip microcomputer. The common keyboard scanning method generally uses matrix scanning, which requires multiple IO ports of the single-chip microcomputer, such as a 12-key keyboard. Button recognition needs to use 7 IO ports (3 rows and 4 columns or 3 columns and 4 rows) to complete. This button detection occupies more MCU IO port resources. When the MCU has more IO ports, the required MCU cost It will be higher. [Summary of the Invention] [0003] The present invention overcomes the shortcomings of the above-mentioned technology and provides a button detection method, by which dozens of buttons can be scanned by using only a few IO ports of the single-chip microcomputer, so that the circuit structure is very simple, and the reliability is hi...

AI Technical Summary

Problems solved by technology

[0002] There are many home appliances on the market with button input, most of which are controlled by single-chip microcomputers. Common keyboard scanning methods generally use matrix scanning, which needs to use multiple IO ports of single-chip microcomputers, such as keyboards with 12 keys. Button recognition requires 7 IO ports (3 rows and 4 columns or 3 columns and 4 rows) to complete. This kind of button detection takes up more IO port resources of the single-chip microcomputer. When there are more IO ports of the single-chip microcomputer, the cost of the single-chip microcomputer will be higher

Images