stmSTM32L476 4x4 Matrix keyboard

Please help
The following is stmSTM32L476 4x4 matrix keyboard working principle

4x3 keyboard starts with no key C1 2 3 connects to 3.3v so it is 1 and output is set to 0

< div class = "aw - list - img > stmSTM32L476 4x4矩阵键盘

< br / > press the 0 key, switch closure

< div class = "aw - list - img > stmSTM32L476 4x4矩阵键盘

< br / > C2 will become 0, judge button in columns C2 above

Set all output to 1 and then 0 from R1

< div class = "aw - list - img > stmSTM32L476 4x4矩阵键盘

< br / > set R2 to 0

< div class = "aw - list - img > stmSTM32L476 4x4矩阵键盘

< br / > Settings R3 is 0

Set R4 to 0 and C2 will change from 1 to 0, judging that the key is on horizontal R4

Below is my code, please help(happy New Year to everyone)


```c

#include "stm32l476xx.h"

#include "keypad.h"

void Keypad_Init() {

    //激活GPIOC 时钟
    RCC->AHB2ENR |= RCC_AHB2ENR_GPIOCEN;

    // Output
    GPIOC->MODER &= ~(GPIO_MODER_MODE0 | GPIO_MODER_MODE1 | GPIO_MODER_MODE2 | GPIO_MODER_MODE3);                        // 设置00 到 PC 0,1,2,3
    GPIOC->MODER |= (GPIO_MODER_MODE0_0 | GPIO_MODER_MODE1_0 | GPIO_MODER_MODE2_0 | GPIO_MODER_MODE3_0);            // 设置01 到 PC 0,1,2,3

    // Input
    GPIOC->MODER &= ~(GPIO_MODER_MODE4 | GPIO_MODER_MODE10 | GPIO_MODER_MODE11 | GPIO_MODER_MODE12);                // 设置00到 PC 4,10,11,12

    // GPIO Output Type: Output push-pull (0, reset), Output open drain (1)
    // Open-drain (need high impendance to avoid the short circuit)
    GPIOC->OTYPER |= (GPIO_IDR_ID0 | GPIO_IDR_ID1 | GPIO_IDR_ID2 | GPIO_IDR_ID3);      //设置1 到PC 0,1,2,3 选择 open train 模式
}

unsigned char keypad_scan() {
    unsigned char row, col;
    unsigned char key;

    unsigned char keymap[4][4] = {
        {'1','2','3','A'},
        {'4','5','6','B'},
        {'7','8','9','C'},
        {'*','0','#','D'}
    };
    /* 这里我做的是 4x4 键盘
    R1          1    2    3   A
    R2          4    5    6   B
    R3          7    8    9   C
    R4          *    0    #   D
                  C1  C2  C3  C4
    */


    // 设置 outputmask 为 1111
    uint32_t  outputMask = GPIO_ODR_OD0 | GPIO_ODR_OD1 | GPIO_ODR_OD2 | GPIO_ODR_OD3;
    // 设置 intputmask 为 1111 
    uint32_t  inputMask = GPIO_IDR_ID4 | GPIO_IDR_ID10 | GPIO_IDR_ID11 | GPIO_IDR_ID12;


    // output 数组
    uint32_t  outputArray[4] = { GPIO_ODR_OD0 , GPIO_ODR_OD1 , GPIO_ODR_OD2 , GPIO_ODR_OD3 };
    // intput 数组
    uint32_t inputArray[4] = { GPIO_IDR_ID4 , GPIO_IDR_ID10 , GPIO_IDR_ID11 , GPIO_IDR_ID12 };

    
    waitms(3);    // 延迟

    while( (GPIOC->IDR & inputMask) == inputMask) {;} // 等待按键 不确定这样对不对

    for(col = 0; col < 4; col++) { // 检测纵列
        
    

        waitms(3); // 延迟

        for(row = 0; row < 4; rol++) { // 检测横排
           
           
            }
        }
    }
    return 0xFF; //如果没有按键 返回0xFF
}

//  延迟fuction 
void waitms(unsigned int ms) {
    int i, j;
    for(i = 0; i < ms; i++) {
        for(j=0; j < 4000; j++);
    }
}