Full-keyboard extended circuit for mobile phone and key scanning method of expanded circuit

Abstract

The invention discloses a full-keyboard extended circuit for a mobile phone and a key scanning method of the expanded circuit. 0-group pins of an I / O port of an I / O extended chip are connected with a plurality of keyboard column input lines; 1-group pins of the I / O port are connected with a plurality of keyboard row output lines; and the plurality of keyboard input lines and the plurality of keyboard output lines form a keyboard matrix. When keys are determined to be pressed, the rows to be scanned are configured to be output I / O ports, and the rest rows are set to be input I / O ports, wherein when the I / O port is set to be the input port, the I / O port is in a high-resistance state and two internal MOS (metal oxide semiconductor) transistors are closed. After the scanning completes, the rows configured to be the output I / O ports are re-set to the input port immediately. When two or more keys on the same column but different rows are pressed, the key rows under scanning are the output port, and the reset rows are input ports and in the high-resistance state, so as to prevent the occurrence of electric leakage and obviate hidden dangers.

Description

technical field [0001] The invention relates to the field of mobile terminal equipment, in particular to a full-keyboard expansion circuit for a mobile phone and a key scanning method thereof. Background technique [0002] In order to meet the requirements of the full keyboard of the mobile phone, it is usually required that the mobile phone platform chip has enough key interfaces. But for many low-end platforms, the number of button interfaces is limited, but there is often a need to design a full keyboard. Therefore, the key interface can be expanded through the I / O expansion chip, but for the mobile phone keys, the I / O expansion chip has some defects. The use of ordinary circuits and scanning methods will affect the performance and even safety of the mobile phone, such as leakage and other safety hazards. Hidden danger. [0003] Therefore, the prior art still needs to be improved and developed. Contents of the invention [0004] The technical problem to be solved by ...

AI Technical Summary

Problems solved by technology

But for many low-end platforms, the number of key interfaces is limited, but there is often a need to design a full keyboard

Therefore, the key interface can be expanded through the I / O expansion chip, but for the mobile phone keys, the I / O expansion chip has some defects. The use of ordinary circuits and scanning methods will affect the performance and even safety of the mobile phone, such as leakage and other safety hazards. Hidden danger

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