Keyboard scanning circuit and scanning method thereof

Abstract

The invention relates to a keyboard scanning circuit and a scanning method thereof, wherein the keyboard scanning circuit comprises a processor with N I / O (input / output) ports, N row lines and N column lines; keys are arranged on the intersections of the row lines and column lines; and one end of each key is connected with a row line, and the other end of the key is connected with a column line. Each I / O port of the processor is a bidirectional I / O port with a pull-up resistor; each row line is connected with a load resistor and then grounded; one end of each column line is connected with an I / O port of the processor; one row line is in pair-wise combination with one column line; a voltage division resistor is arranged between the row line and column line in the pair-wise combination; andthe pull-up resistor, the voltage division resistor and the load resistor in each combination form a tandem passage. The keyboard scanning circuit is only required a processor with 2N resistor elements and N I / O ports to finish scanning of N*N keys, has the advantages of strong stability in circuit structure and the like, occupies the fewer I / O ports of the processor, and is low in the manufacturing cost.

Description

technical field [0001] The invention relates to a matrix keyboard scanning circuit and a scanning method of the matrix keyboard scanning circuit. Background technique [0002] A keyboard is an important human-computer interaction component in an electronic device, and most keyboards use a processor I / O port to scan the keyboard. Existing keyboard circuits such as figure 1 The 4×4 matrix keyboard is shown as an example, including 16 keys arranged in 4 rows and 4 columns. Each row line and each column line need to be connected to an I / O port. This keyboard requires 8 I / O ports. By analogy, an N×N matrix keyboard circuit requires 2N I / O ports. The scanning of the keyboard adopts the row and column scanning method to determine the row and column position of the pressed button. [0003] The row-column scanning method refers to: setting the I / O port corresponding to the row line of the button as an output port, and setting the I / O port corresponding to the column line as an inp...

AI Technical Summary

Problems solved by technology

Using this kind of keyboard circuit, if the number of keys is N×N, the processor needs to have 2N I / O ports, and the keyboard occupies more I / O ports. For processors with tight I / O ports It is undoubtedly a large waste of resources

[0004] In order to solve the above-mentioned problem that the matrix keyboard occupies a large number of I / O ports, some electronic devices add a large number of components such as diodes and parallel-to-serial chips to the matrix keyboard circuit, and these components are easy to cause damage during use. As a result, the stability of the matrix keyboard is reduced, and the cost of the matrix keyboard will also be greatly increased. It is not as stable and reliable as the circuit of the matrix keyboard composed of buttons plus resistors, and the cost is low.

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