STM32-HAL-Keypad

Overview

This is a simple library for STM32 32-bit Arm Cortex MCUs to work with a 4x4 Matrix Keypad.

To develop this library it was used STM32CubeIDE and HAL APIs to interact with peripherals and low-level resources.

In this repository you will find the keypad library, ready to attach to your new project and a project example, tested with the STM32F4DISCOVERY board.

Examples

SMT32F4DISCOVERY

Brief description of the example attached

Keypad_HandleTypeDef keypad_init(void);

uint8_t key = 0;

int main(){
    Keypad_HandleTypeDef keypad = keypad_init();
    while(1){
        while(!key_selected(&keypad, &key));
    }
}

Keypad_HandleTypeDef keypad_init(void){

    Keypad_HandleTypeDef keypad;
    
    Keypad_PinDef pin_columns[4] = {COLUMN_1_Pin, COLUMN_2_Pin, COLUMN_3_Pin, COLUMN_4_Pin};
    Keypad_PortDef port_columns[4] = { COLUMN_1_GPIO_Port, COLUMN_2_GPIO_Port, COLUMN_3_GPIO_Port, COLUMN_4_GPIO_Port };
    
    Keypad_PinDef pin_rows[4] = {ROW_1_Pin, ROW_2_Pin, ROW_3_Pin, ROW_4_Pin};
    Keypad_PortDef port_rows[4] = { ROW_1_GPIO_Port, ROW_2_GPIO_Port, ROW_3_GPIO_Port, ROW_4_GPIO_Port };
    
    keypad = keypad_create(pin_rows, port_rows, pin_columns, port_columns);
    
    return keypad;
}

In this example, the process will stop running until you press a button. Adding the key variable to the Live Expression tab, while debugging, will show you the pressed key.

Documentation

A brief documentation of the structures and functions provided by the library are shown below. For detailed instructions, refer to the doxygen compliant documentation within the keypad.c file.

Macro definitions

List of macro definitions with a brief description is shown below.

Name	Description
Keypad_PinDef	Macro specific to define GPIO pins data type i.e. uint16_t
Keypad_PortDef	Macro specific to define GPIO ports data type i.e. GPIO_TypeDef*

Structure

List of structures provided with the library with a brief description is shown below.

Name	Description
Keypad_HandleTypeDef	Struct to handle the GPIO pins and ports for columns and rows

Functions

List of functions provided with the library with a brief description is shown below.

Name	Description
keypad_create	Store GPIO pins and ports and returns a Keypad_HandleTypeDef handler
key_selected	Iterate over GPIO pins used as columns and GPIO pins used as rows until the user press a key. Once this is done the function returns 1 and overwrite the current key value with the new character pressed