How to connect KEYPAD-SMALLCALC and LCD - c

Question

I'm working on calculator project using LM3S316 microcontroller & Keil software
I have some confusion about how can I work with KEYPAD-SMALLCALC
So, my question is :
how can I use this keypad and initialize it
also, how can I represent values and use it
finally, how to connect it with LCD
Thank You

Answer 1

The KEYPAD-SMALL-CALC is a matrix keypad, meaning you should configure some pins as input and some pins as output.
This is a decent library that i personally have used for a project of mine using a matrix keypad - https://github.com/nimaltd/KeyPad
You should be able to integrate it in your code without too much issues.
In short you have cols and rows. In the example provided the rows are input pins and the cols are output pins. There is a for cycle that is checking for a button press. By default rows are high, once a button is pressed the library checks for a combination between row and col that determinate which button has been pressed.
For configuration pins the easiest way would probably to use software such as "STM32CubeMX" which generates c code with your MCU configuration, you can easily configurate there the matrix keypad rows, cols and decide which pins you should use for the LCD.
Edit : Here is a modified version of the github library i have personally used in a project
source keyboard.c
#include "keyboard.h"
//#define _KEYPAD_DELAY(x) HAL_Delay(x)
const GPIO_TypeDef* _KEYPAD_COLUMN_GPIO_PORT[] =
{
COL_1_GPIO_Port,
COL_2_GPIO_Port,
COL_3_GPIO_Port,
COL_4_GPIO_Port,
COL_5_GPIO_Port,
COL_6_GPIO_Port,
COL_7_GPIO_Port,
COL_8_GPIO_Port
};
const uint16_t _KEYPAD_COLUMN_GPIO_PIN[] =
{
COL_1_Pin,
COL_2_Pin,
COL_3_Pin,
COL_4_Pin,
COL_5_Pin,
COL_6_Pin,
COL_7_Pin,
COL_8_Pin
};
const GPIO_TypeDef* _KEYPAD_ROW_GPIO_PORT[] =
{
ROW_1_GPIO_Port,
ROW_2_GPIO_Port,
ROW_3_GPIO_Port,
ROW_4_GPIO_Port
};
const uint16_t _KEYPAD_ROW_GPIO_PIN[] =
{
ROW_1_Pin,
ROW_2_Pin,
ROW_3_Pin,
ROW_4_Pin
};
KeyPad_t KeyPad;
//#############################################################################################
void KeyPad_Init(void)
{
KeyPad.ColumnSize = sizeof(_KEYPAD_COLUMN_GPIO_PIN)/2;
KeyPad.RowSize = sizeof(_KEYPAD_ROW_GPIO_PIN)/2;
}
//#############################################################################################
uint16_t KeyPad_Scan(void)
{
uint16_t key = 0;
uint8_t hold_key = 0;
int int_btn_cnt = 0;
int int_button_state_change = 0;
GPIO_PinState int_button_current_state = GPIO_PIN_SET;
GPIO_PinState int_button_last_state = GPIO_PIN_SET;
for(uint8_t c=0 ; c<KeyPad.ColumnSize ; c++)
{
for(uint8_t i=0 ; i<KeyPad.ColumnSize ; i++)
HAL_GPIO_WritePin((GPIO_TypeDef*)_KEYPAD_COLUMN_GPIO_PORT[i],_KEYPAD_COLUMN_GPIO_PIN[i],GPIO_PIN_SET);
HAL_GPIO_WritePin((GPIO_TypeDef*)_KEYPAD_COLUMN_GPIO_PORT[c],_KEYPAD_COLUMN_GPIO_PIN[c],GPIO_PIN_RESET);
for(uint8_t r=0 ; r<KeyPad.RowSize ; r++){
while(HAL_GPIO_ReadPin((GPIO_TypeDef*)_KEYPAD_ROW_GPIO_PORT[r],_KEYPAD_ROW_GPIO_PIN[r])==GPIO_PIN_RESET){
int_btn_cnt++;
if(int_btn_cnt == _KEYPAD_DEBOUNCE_TIME_MS){
key |= 1<<c;
key |= 1<<(r+8);
return key;
}
}
int_btn_cnt = 0;
}
}
return key;
}
//#############################################################################################
uint16_t KeyPad_WaitForKey(uint32_t Timeout_ms)
{
volatile uint16_t keyRead;
while(Timeout_ms==0)
{
keyRead = KeyPad_Scan();
if(keyRead!=0)
{
KeyPad.LastKey = keyRead;
return keyRead;
}
}
uint32_t StartTime = HAL_GetTick();
while(HAL_GetTick()-StartTime < Timeout_ms)
{
keyRead = KeyPad_Scan();
if(keyRead!=0){
KeyPad.LastKey = keyRead;
return keyRead;
}
}
return 0;
}
//#############################################################################################
char KeyPad_WaitForKeyGetChar(uint32_t Timeout_ms)
{
char result = 0;
switch(KeyPad_WaitForKey(Timeout_ms))
{
case 0x802: // ^
result = '^';
break;
case 0x804: // 7
result = '7';
break;
case 0x808: // 7
result = '8';
break;
case 0x810: // 9
result = '9';
break;
case 0x820: // 04
result = 0xFF;
break;
case 0x840: // D+
result = 0xFE;
break;
case 0x880: // M
result = 'M';
break;
case 0x401: // -%
result = '-';
break;
case 0x402: // +%
result = '+';
break;
case 0x404: // 4
result = '4';
break;
case 0x408: // 6
result = '5';
break;
case 0x410: // 6
result = '6';
break;
case 0x420: // 03
result = 0xFD;
break;
case 0x440: // PRUREP
result = 0xFC;
break;
case 0x480: // STL
result = 0xFB;
break;
case 0x201: // ALT
result = 0xFA;
break;
case 0x202: // CLK
result = 0xF9;
break;
case 0x204: // 1
result = '1';
break;
case 0x208: // 3
result = '2';
break;
case 0x210: // 3
result = '3';
break;
case 0x220: // 02
result = 0xF8;
break;
case 0x240: // PY1 RA
result = 0xF7;
break;
case 0x101: // C
result = 'C';
break;
case 0x102: // VD
result = 0xF6;
break;
case 0x104: // 0
result = '0';
break;
case 0x108: // .
result = '.';
break;
case 0x110: // QTY
result = 0xF5;
break;
case 0x120: // 01
result = 0xF4;
break;
case 0x140: // PY2PO
result = 0xF3;
break;
case 0x180: // TL
result = 0xF2;
break;
}
return result;
}
and the header file keyboard.h
#ifndef __KEYBOARD_H__
#define __KEYBOARD_H__
#include <stdint.h>
#include <stdbool.h>
typedef struct
{
uint8_t ColumnSize;
uint8_t RowSize;
uint16_t LastKey;
}KeyPad_t;
void KeyPad_Init(void);
uint16_t KeyPad_WaitForKey(uint32_t Timeout_ms);
char KeyPad_WaitForKeyGetChar(uint32_t Timeout_ms);
#define _KEYPAD_DEBOUNCE_TIME_MS 5
#endif /* __KEYBOARD_H__ */
You should only configure the const arrays with the ports and pins you are planning to use and use the library like this :
init keyboard at the start of your program:
KeyPad_Init();
and use it like this
uint8_t key = KeyPad_WaitForKeyGetChar(1); // wait 1 ms
key is the value of the pressed key, if you use KeyPad_WaitForKeyGetChar(0) the code will stay here and wait for a key press.
Hope it helps!