Keypad Library

The mikroC PRO for ARM provides a library for working with 4x4 keypad. The library routines can also be used with 4x1, 4x2, or 4x3 keypad. For connections explanation see schematic at the bottom of this page.

External dependencies of Keypad Library

Stellaris

The following variable must be defined in all projects using Keypad Library:	Description :	Example :
`extern sfr unsigned long keypadPort;`	Keypad Port.	`unsigned long keypadPort at GPIO_PORTH_DATA;`
`extern sfr unsigned long keypadPort_Direction;`	Keypad Port direction.	`unsigned long keypadPort_Direction at GPIO_PORTH_DIR;`

STM32

The following variable must be defined in all projects using Keypad Library:	Description :	Example :
`extern sfr unsigned long keypadPort_Input;`	Keypad Input Port.	`unsigned long keypadPort_Input at GPIOD_IDR;`
`extern sfr unsigned long keypadPort_Output;`	Keypad Output Port.	`unsigned long keypadPort_Output at GPIOD_ODR;`

Keypad_Init

Prototype	void Keypad_Init();
Description	Initializes given port for working with keypad.
Parameters	None.
Returns	Nothing.
Requires	External dependencies of the library from the top of the page must be defined before using this function.
Example	Stellaris // Keypad module connections unsigned long keypadPort at GPIO_PORTH_DATA; unsigned long keypadPort_Direction at GPIO_PORTH_DIR; // End Keypad module connections ... Keypad_Init(); STM32 // Keypad module connections unsigned long keypadPort_Input at GPIOD_IDR; unsigned long keypadPort_Output at GPIOD_ODR; // End Keypad module connections ... Keypad_Init();
Notes	The Keypad library uses lower byte (bits <7..0>) of `keypadPort`.

Keypad_Key_Press

Prototype	unsigned Keypad_Key_Press();
Description	Reads the key from keypad when key gets pressed.
Parameters	None.
Returns	The code of a pressed key (1..16). If no key is pressed, returns 0.
Requires	Port needs to be initialized for working with the Keypad library, see Keypad_Init.
Example	unsigned kp; ... kp = Keypad_Key_Press();
Notes	None.

Keypad_Key_Click

Prototype	unsigned Keypad_Key_Click();
Description	Call to `Keypad_Key_Click` is a blocking call: the function waits until some key is pressed and released. When released, the function returns 1 to 16, depending on the key. If more than one key is pressed simultaneously the function will wait until all pressed keys are released. After that the function will return the code of the first pressed key.
Parameters	None.
Returns	The code of a clicked key (1..16). If no key is clicked, returns 0.
Requires	Port needs to be initialized for working with the Keypad library, see Keypad_Init.
Example	kp = Keypad_Key_Click();
Notes	None.

Library Example

The following code can be used for testing the keypad. It is written for keypad_4x3 or 4x4. The code returned by the keypad functions (1..16) is transformed into ASCII codes [0..9,A..F], and then displayed on Lcd.

Stellaris

Copy Code To Clipboard

unsigned short kp, cnt, oldstate = 0;
char txt[6];

// Keypad module connections
unsigned long keypadPort at GPIO_PORTH_DATA;
unsigned long keypadPort_Direction at GPIO_PORTH_DIR;
// End Keypad module connections

// LCD module connections
sbit LCD_RS at GPIO_PORTD_DATA.B2;
sbit LCD_EN at GPIO_PORTD_DATA.B3;
sbit LCD_D4 at GPIO_PORTD_DATA.B4;
sbit LCD_D5 at GPIO_PORTD_DATA.B5;
sbit LCD_D6 at GPIO_PORTD_DATA.B6;
sbit LCD_D7 at GPIO_PORTD_DATA.B7;

sbit LCD_RS_Direction at GPIO_PORTD_DIR.B2;
sbit LCD_EN_Direction at GPIO_PORTD_DIR.B3;
sbit LCD_D4_Direction at GPIO_PORTD_DIR.B4;
sbit LCD_D5_Direction at GPIO_PORTD_DIR.B5;
sbit LCD_D6_Direction at GPIO_PORTD_DIR.B6;
sbit LCD_D7_Direction at GPIO_PORTD_DIR.B7;
// End LCD module connections

void main() {

  cnt = 0;                                 // Reset counter
  Keypad_Init();                           // Initialize Keypad
  Lcd_Init();                              // Initialize LCD
  Lcd_Cmd(_LCD_CLEAR);                     // Clear display
  Lcd_Cmd(_LCD_CURSOR_OFF);                // Cursor off
  Lcd_Out(1, 1, "1");
  Lcd_Out(1, 1, "Key  :");                 // Write message text on LCD
  Lcd_Out(2, 1, "Times:");

  do {
    kp = 0;                                // Reset key code variable
    // Wait for key to be pressed and released
    do
      // kp = Keypad_Key_Press();          // Store key code in kp variable
      kp = Keypad_Key_Click();             // Store key code in kp variable
    while (!kp);
   // Prepare value for output, transform key to it's ASCII value
    switch (kp) {
      //case 10: kp = 42; break;  // '*'   // Uncomment this block for keypad4x3
      //case 11: kp = 48; break;  // '0'
      //case 12: kp = 35; break;  // '#'
      //default: kp += 48;

      case  1: kp = 49; break; // 1        // Uncomment this block for keypad4x4
      case  2: kp = 50; break; // 2
      case  3: kp = 51; break; // 3
      case  4: kp = 65; break; // A
      case  5: kp = 52; break; // 4
      case  6: kp = 53; break; // 5
      case  7: kp = 54; break; // 6
      case  8: kp = 66; break; // B
      case  9: kp = 55; break; // 7
      case 10: kp = 56; break; // 8
      case 11: kp = 57; break; // 9
      case 12: kp = 67; break; // C
      case 13: kp = 42; break; // *
      case 14: kp = 48; break; // 0
      case 15: kp = 35; break; // #
      case 16: kp = 68; break; // D

    }

    if (kp != oldstate) {                  // Pressed key differs from previous
      cnt = 1;
      oldstate = kp;
      }
    else {                                 // Pressed key is same as previous
      cnt++;
      }

    Lcd_Chr(1, 10, kp);                    // Print key ASCII value on LCD

    if (cnt == 255) {                      // If counter varialble overflow
      cnt = 0;
      Lcd_Out(2, 8, "   ");
      }

    ByteToStr(cnt, txt);                   // Transform counter value to string
    Lcd_Out(2, 8, txt);                   // Display counter value on LCD
  } while (1);
}

STM32

Copy Code To Clipboard

unsigned short kp, cnt, oldstate = 0;
char txt[6];

// Keypad module connections
unsigned long keypadPort_Input  at GPIOD_IDR;
unsigned long keypadPort_Output at GPIOD_ODR;
// End Keypad module connections

// LCD module connections
sbit LCD_RS at GPIOD_ODR.B10;
sbit LCD_EN at GPIOD_ODR.B11;
sbit LCD_D4 at GPIOD_ODR.B12;
sbit LCD_D5 at GPIOD_ODR.B13;
sbit LCD_D6 at GPIOD_ODR.B14;
sbit LCD_D7 at GPIOD_ODR.B15;
// End LCD module connections

void main() {

  cnt = 0;                                 // Reset counter
  Keypad_Init();                           // Initialize Keypad
  Lcd_Init();                              // Initialize LCD
  Lcd_Cmd(_LCD_CLEAR);                     // Clear display
  Lcd_Cmd(_LCD_CURSOR_OFF);                // Cursor off
  Lcd_Out(1, 1, "1");
  Lcd_Out(1, 1, "Key  :");                 // Write message text on LCD
  Lcd_Out(2, 1, "Times:");

  do {
    kp = 0;                                // Reset key code variable
    // Wait for key to be pressed and released
    do
      // kp = Keypad_Key_Press();          // Store key code in kp variable
      kp = Keypad_Key_Click();             // Store key code in kp variable
    while (!kp);
    
    // Prepare value for output, transform key to it's ASCII value
    switch (kp) {
      //case 10: kp = 42; break;  // '*'   // Uncomment this block for keypad4x3
      //case 11: kp = 48; break;  // '0'
      //case 12: kp = 35; break;  // '#'
      //default: kp += 48;

      case  1: kp = 49; break; // 1        // Uncomment this block for keypad4x4
      case  2: kp = 50; break; // 2
      case  3: kp = 51; break; // 3
      case  4: kp = 65; break; // A
      case  5: kp = 52; break; // 4
      case  6: kp = 53; break; // 5
      case  7: kp = 54; break; // 6
      case  8: kp = 66; break; // B
      case  9: kp = 55; break; // 7
      case 10: kp = 56; break; // 8
      case 11: kp = 57; break; // 9
      case 12: kp = 67; break; // C
      case 13: kp = 42; break; // *
      case 14: kp = 48; break; // 0
      case 15: kp = 35; break; // #
      case 16: kp = 68; break; // D

    }

    if (kp != oldstate) {                  // Pressed key differs from previous
      cnt = 1;
      oldstate = kp;
    }
    else {                                 // Pressed key is same as previous
      cnt++;
    }

    Lcd_Chr(1, 10, kp);                    // Print key ASCII value on LCD

    if (cnt == 255) {                      // If counter varialble overflow
      cnt = 0;
      Lcd_Out(2, 8, "   ");
    }

    ByteToStr(cnt, txt);                   // Transform counter value to string
    Lcd_Out(2, 8, txt);                    // Display counter value on LCD
  } while (1);
}

Copy Code To Clipboard

Want more examples and libraries?
Find them on