Row/column matrix keyboard interface circuit and row/column matrix keyboard scanning method

Abstract

The invention discloses a row / column matrix keyboard interface circuit and a row / column matrix keyboard scanning method. The interface circuit comprises a microcontroller and a touch chip. M resistors as row resistors are connected between a pin X+ and a pin X- of the touch chip in series. N resistors as column resistors are connected between the pin X+ and the pin X- in series. A column line is leaded out between two adjacent column resistors. A row line is leaded out between two adjacent row resistors. A key is arranged at an intersection of each row line and each column line. A resistor network is constructed by utilization of the touch chip. A voltage gradient is formed. The matrix keyboard with any row / column number can be realized only through 3-4 I / O ports of the microcontroller according to a touch screen principle. The usage number of the I / O ports of the microcontroller is reduced. More I / O port resources are left for other external devices. Moreover, the location of the pressed key is determined by the touch screen chip through adoption of hardware scanning, so the key scanning workload of the microcontroller is greatly simplified. The interface circuit and the method have great application value in the field of the externally connected matrix keyboard of the microcontroller.

Description

technical field [0001] The invention relates to the field of circuits, in particular to a row-column matrix keyboard interface circuit and a row-column matrix keyboard scanning method. Background technique [0002] At present, there are two main types of single-chip button circuit design, one is the independent button structure, that is, one I / O port corresponds to one button; the other is the matrix keyboard structure, see figure 1 , when there are many keys in the keyboard, in order to reduce the occupation of the I / O port, the keys are usually arranged in a matrix form. In a matrix keyboard, each horizontal and vertical line is not directly connected at the intersection, but is connected by a key. In this way, one port (such as P1 port) can form 4*4=16 keys, which is twice as much as using the port line directly for the keyboard, and the more lines there are, the more obvious the difference is, for example, adding one more line Just can form the keyboard of 20 keys, and...

AI Technical Summary

Problems solved by technology

[0003] The I / O port resources of the single-chip microcomputer are very limited, and the above-mentioned independent key structure is the most wasteful of the I / O port resources, and one I / O port corresponds to a key; the general matrix keyboard structure saves more I than the independent key structure. / O port resources, but when there are 16 buttons, 8 I / O ports need to be used, which does not save I / O port resources very much.

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