HM Yoong / keypad

An interrupt-driven interface to 4x4 keypad.

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Keypad Class Reference
Public Member Functions

Keypad Class Reference

An interrupt-based interface to 4x4 keypad. More...

#include <Keypad.h>

Public Member Functions

 Keypad (PinName r0, PinName r1, PinName r2, PinName r3, PinName c0, PinName c1, PinName c2, PinName c3, int debounce_ms=20)
 Create a 4x4 (row, col) or 4x3 keypad interface:
 ~Keypad ()
 Destructor.
void start (void)
 Start the keypad interrupt routines.
void stop (void)
 Stop the keypad interrupt routines.
void attach (uint32_t(*fptr)(uint32_t))
 User-defined function that to be called when a key is pressed.

Detailed Description

An interrupt-based interface to 4x4 keypad.

On each key pressed on a keypad, the index of the key is passed to a user-defined function. User is free to define what to be done with the input.

Example: 

 #include "mbed.h"
 #include "Keypad.h"

 // Define your own keypad values
 char Keytable[] = { '1', '2', '3', 'A',   // r0
                     '4', '5', '6', 'B',   // r1
                     '7', '8', '9', 'C',   // r2
                     '*', '0', '#', 'D'    // r3
                   };
                  // c0   c1   c2   c3

 uint32_t Index;

 uint32_t cbAfterInput(uint32_t index) {
     Index = index;
     return 0;
 }

 int main() {
                 // r0   r1   r2   r3   c0   c1   c2   c3
     Keypad keypad(p21, p22, p23, p24, p25, p26, p27, p28);
     keypad.attach(&cbAfterInput);
     keypad.start();  // energize the keypad via c0-c3

     while (1) {
         __wfi();
         printf("Interrupted\r\n");
         printf("Index:%d => Key:%c\r\n", Index, Keytable[Index]);
     }
 }

Definition at line 72 of file Keypad.h.

Constructor & Destructor Documentation

Keypad ( PinName  r0,
PinName  r1,
PinName  r2,
PinName  r3,
PinName  c0,
PinName  c1,
PinName  c2,
PinName  c3,
int  debounce_ms = 20 
)

Create a 4x4 (row, col) or 4x3 keypad interface:

| Col0 | Col1 | Col2 | Col3 -------+------+------+------+----- Row 0 | x | x | x | x Row 1 | x | x | x | x Row 2 | x | x | x | x Row 3 | x | x | x | x

Parameters:
row<0..3>Row data lines
col<0..3>Column data lines
debounce_msDebounce in ms (Default to 20ms)

Definition at line 49 of file Keypad.cpp.

~Keypad (  )

Destructor.

Definition at line 91 of file Keypad.cpp.

Member Function Documentation

void attach ( uint32_t(*)(uint32_t)  fptr )

User-defined function that to be called when a key is pressed.

Parameters:
fptrA function pointer takes a uint32_t and returns uint32_t
void start ( void   )

Start the keypad interrupt routines.

Definition at line 106 of file Keypad.cpp.

void stop ( void   )

Stop the keypad interrupt routines.

Definition at line 115 of file Keypad.cpp.

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