Keypad Library
The mikroC PRO for PIC32 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 atomic unsigned long keypadPort; |
Keypad Port. | unsigned keypadPort at PORTB; |
extern sfr atomic unsigned long keypadPort_Direction; |
Keypad Port direction. | unsigned keypadPort_Direction at TRISB; |
Library Routines
Keypad_Init
Prototype |
void Keypad_Init(); |
---|---|
Description |
Initializes given port for working with keypad. |
Parameters |
None. |
Returns |
Nothing. |
Requires |
Global variable :
|
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 |
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 |
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.
unsigned short kp, oldstate = 0;
char txt[6];
// Keypad module connections
unsigned long keypadPort at PORTD;
unsigned long keypadPort_Direction at TRISD;
// End Keypad module connections
void main() {
AD1PCFG = 0xFFFF;
CHECON = 0x32;
UART1_Init(19200); // Initialize UART module at 9600 bps
Delay_ms(10);
Keypad_Init(); // Initialize Keypad
UART1_Write_Text("Press any key on your keypad...");
UART1_Write(10);
UART1_Write(13);
LATD = 0;
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_Text("Key pressed: ");
UART1_Write(kp); // Send value of pressed button to UART
UART1_Write(10);
UART1_Write(13);
} while (1);
}
HW Connection
4x4 Keypad connection scheme
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