I would like to build a code that displays the pressed button when a button is pressed on a $4$x$4$ keypad. When you run the code below, the vertical columns will output the same value. $($Press keypad $"4"$ to display $1$; press keypad $"8"$ to display $2.)$ Please teach me what is wrong and how to correct it$.$

$/*$ Template to help create the scan function. Refer to the scanning algorithm in lecture$/$book section $15\mathrm{.}9*/$

#include

#include

#include $"$stm$32$l$476$xx$.$h$"$

#include "UART.h$"$

#include "SysClock.h$"$

#include "keypad.h$"//$ Include keypad header file

$//$ Let us make configs in one function and declare in the header file. Much better, right?

void Keypad$\_$Init$()\{$

UART$2\_$Init$()$;

System$\_$Clock$\_$Init$()$;

$//$ Port C config. Go to the header file as shown in class. Check your header file for macros.

$//$ Enable GPIO clock

RCC$->$AHB$2$ENR $|=$ RCC$\_$AHB$2$ENR$\_$GPIOCEN;

$//$ Setting PC pins $0,1,2,3$ as GPIO output

$//$ GPIO Mode: Input$(00),$ Output$(01),$ AlterFunc$(10),$ Analog$(11,$ reset$)$

GPIOC$->$MODER &$=$ ~$($GPIO$\_$MODER$\_$MODE$0|$ GPIO$\_$MODER$\_$MODE$1|$ GPIO$\_$MODER$\_$MODE$2|$ GPIO$\_$MODER$\_$MODE$3)$;

GPIOC$->$MODER $|=($GPIO$\_$MODER$\_$MODE$0\_0|$ GPIO$\_$MODER$\_$MODE$1\_0|$ GPIO$\_$MODER$\_$MODE$2\_0|$ GPIO$\_$MODER$\_$MODE$3\_0)$; $//$ Output

$//$ Setting PC pins $4,10,11,12$ as GPIO input

$//$ GPIO Mode: Input$(00),$ Output$(01),$ AlterFunc$(10),$ Analog$(11,$ reset$)$

GPIOC$->$MODER &$=$ ~$($GPIO$\_$MODER$\_$MODE$4|$ GPIO$\_$MODER$\_$MODE$10|$ GPIO$\_$MODER$\_$MODE$11|$ GPIO$\_$MODER$\_$MODE$12)$; $//$ Input

$//$ GPIO Output Type: Output push$-$pull $(0,$ reset$),$ Output open drain $(1)$

GPIOC$->$OTYPER &$=$ ~$($GPIO$\_$OTYPER$\_$OT$0|$ GPIO$\_$OTYPER$\_$OT$1|$ GPIO$\_$OTYPER$\_$OT$2|$ GPIO$\_$OTYPER$\_$OT$3)$; $//$ Push$-$pull

$\}$

unsigned char keypad$\_$scan$()\{$

unsigned char row, col;

unsigned char key;

unsigned char keymap$[4][4]=\{$

$\{\text{'}1\text{'},\text{'}2\text{'},\text{'}3\text{'},\text{'}$A$\text{'}\},$

$\{\text{'}4\text{'},\text{'}5\text{'},\text{'}6\text{'},\text{'}$B$\text{'}\},$

$\{\text{'}7\text{'},\text{'}8\text{'},\text{'}9\text{'},\text{'}$C$\text{'}\},$

$\{\text{'}*\text{'},\text{'}0\text{'},\text{'}$#$\text{'},\text{'}$D$\text{'}\}$

$\}$;

$//$ Define$/$initialize two integers, for "input" and "output" masks assignments.

uint$32\_$t input$\_$mask $=$ GPIO$\_$IDR$\_$ID$4|$ GPIO$\_$IDR$\_$ID$10|$ GPIO$\_$IDR$\_$ID$11|$ GPIO$\_$IDR$\_$ID$12$; $//$ input mask

uint$32\_$t output$\_$mask $=$ GPIO$\_$ODR$\_$OD$0|$ GPIO$\_$ODR$\_$OD$1|$ GPIO$\_$ODR$\_$OD$2|$ GPIO$\_$ODR$\_$OD$3$; $//$ output mask

$//$ Masking outputs array

uint$32\_$t outputArray$[4]=\{$ GPIO$\_$ODR$\_$OD$0,$ GPIO$\_$ODR$\_$OD$1,$ GPIO$\_$ODR$\_$OD$2,$ GPIO$\_$ODR$\_$OD$3\}$;

$//$ Masking inputs array

uint$32\_$t inputArray$[4]=\{$ GPIO$\_$IDR$\_$ID$4,$ GPIO$\_$IDR$\_$ID$10,$ GPIO$\_$IDR$\_$ID$11,$ GPIO$\_$IDR$\_$ID$12\}$;

waitms$(3)$; $//$ short delay debounce

$//$ Wait until key pressed

while $(($GPIOC$->$IDR & input$\_$mask$)==$ input$\_$mask$)$;

for $($row $=0$; row $<4$; row$++)\{//$ Row scan

$//$ Set all rows to Output

GPIOC$->$MODER &$=$ ~$($GPIO$\_$MODER$\_$MODE$0|$ GPIO$\_$MODER$\_$MODE$1|$ GPIO$\_$MODER$\_$MODE$2|$ GPIO$\_$MODER$\_$MODE$3)$;

GPIOC$->$MODER $|=($GPIO$\_$MODER$\_$MODE$0\_0|$ GPIO$\_$MODER$\_$MODE$1\_0|$ GPIO$\_$MODER$\_$MODE$2\_0|$ GPIO$\_$MODER$\_$MODE$3\_0)$; $//$ Output

$//$ Set current row to low

GPIOC$->$ODR &$=$ ~outputArray$[$row$]$;

waitms$(3)$; $//$ short delay

for $($col $=0$; col $<4$; col$++)\{//$ Column scan

if $(($GPIOC$->$IDR & inputArray$[$col$])==0)\{$

$//$ Grab the chosen key

key $=$ keymap$[$row$][$col$]$;

$//$ Wait until key released

while $(($GPIOC$->$IDR & inputArray$[$col$])==0)$;

return key; $//$ return the key pressed

$\}$

$\}$

$\}$

return $0$xFF; $//$ Nothing is going on$,$ No press of any key

$\}$

$//$ Delay function

void waitms$($unsigned int ms$)\{$

int i$,$ j;

for $($i $=0$; i $<$ ms; i$++)\{$

for $($j $=0$; j $<4000$; j$++)$;

$\}$

$\}$

int main$()\{$

Keypad$\_$Init$()$; $//$ Initialize keypad

while $(1)\{$

unsigned char key $=$ keypad$\_$scan$()$; $//$ Scan keypad for key press

if $($key $!=0$xFF$)\{$

printf$("$Pressed key: $\%$c$\backslash$r

$",$ key$)$; $//$ Print the pressed key

$\}$

$\}$

$\}$