Keypad Library

The mikroC PRO for dsPIC30/33 and PIC24 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

The following variable must be defined in all projects using Keypad Library:	Description :	Example :
`extern sfr unsigned int keypadPort;`	Keypad Port.	`unsigned keypadPort at PORTB;`

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	// Keypad module connections char unsigned at PORTB; // End of 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 sent via UART1.

Copy Code To Clipboard

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

// Keypad module connections
unsigned keypadPort at PORTB;
unsigned keypadPort_Direction at TRISB;
// End Keypad module connections

void main() {
  ADPCFG = 0xFFFF;
  UART1_Init(9600);
  Delay_ms(100);
  Keypad_Init();                           // Initialize Keypad

  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

    }
    UART1_Write(kp);                       // Send value of pressed button to UART
  } while (1);
}

HW Connection

4x4 Keypad connection scheme

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