Stm32f1 and stm32cubeide programming example - matrix keyboard driver

Matrix keyboard driver

1、 Matrix keyboard introduction

Keyboard is an input device widely used in various electronic and embedded projects . They are used to get input in the form of numbers and letters , And input it into the system for further processing .

The matrix keyboard consists of a set of interconnected buttons . In this example, use 4X4 Matrix keyboard , Each of the four lines has 4 Button . The button terminal shall be connected as shown in the figure below . In the first line , all 4 One terminal of each button is connected together ,4 The other terminal of the button represents 4 Each column in the column , The same goes for every line . So there is 8 Root cable to connect a microcontroller .

First , Need configuration 8 individual GPIO Pin . Four of them are input , The other four are output pins . You can then connect the column pins to the input or output pins , But for convenience , I connect them to 4 Two output pins .

Last but not least ,4 The row pins will be connected to the... Of the microcontroller 4 Two input pins . As shown in the figure below ：

How to determine which key in the keyboard is pressed ？

1） Find column position

• First , Set all rows to logical level 0, Set all columns to logical level 1.
• Whenever a key is pressed , The columns and rows corresponding to the button will be short circuited , And change the corresponding column to logic level 0. Because the column is connected （ A short circuit ） To be at logic level 0 The line of .