File content as of revision 0:9fd3dad2dc25:

#include "mbed.h"
#include "USBKeyboard.h"
#include "hid_keys.h"

#define MAX_ROWS 5
#define MAX_COLS 14
#define REPORT_LEN 9
#define REPORT_ID_KEYBOARD 1

const uint8_t hid_keys[MAX_ROWS * MAX_COLS] = 
{
    KEY_PERIOD,     KEY_L,          KEY_O,      KEY_9,      KEY_BACKSPACE,
    KEY_SLASH,      KEY_SEMICOLON,  KEY_P,      KEY_0,      KEY_NONE,
    KEY_NONE,       KEY_EQUALS,     KEY_UP_ARROW,   KEY_MINUS, KEY_NONE,
    KEY_DELETE,     KEY_ENTER,      KEY_DOWN_ARROW, KEY_LEFT_ARROW, KEY_NONE,
    KEY_SPACE,      KEY_NONE,       KEY_OPEN_SQUARE, KEY_RIGHT_ARROW, KEY_NONE,
    KEY_COMMA,      KEY_K,          KEY_I,      KEY_8,      KEY_NONE,
    KEY_M,          KEY_J,          KEY_U,      KEY_7,      KEY_NONE,
    KEY_N,          KEY_H,          KEY_Y,      KEY_6,      KEY_NONE,
    KEY_B,          KEY_G,          KEY_T,      KEY_5,      KEY_NONE,
    KEY_V,          KEY_F,          KEY_R,      KEY_4,      KEY_NONE,
    KEY_C,          KEY_D,          KEY_E,      KEY_3,      KEY_NONE,
    KEY_X,          KEY_S,          KEY_W,      KEY_2,      KEY_NONE,
    KEY_Z,          KEY_A,          KEY_Q,      KEY_1,      KEY_NONE,
    KEY_LEFT_SHIFT, KEY_LEFT_CTRL,  KEY_TAB,    KEY_ESC,    KEY_NONE,
};


BusOut leds(LED1, LED2, LED3);

BusOut scanCols(
    PTC10,PTC8, 
    PTC6, PTA5,   
    PTC5, PTA4,  
    PTC4, PTA12,
    PTC3, PTD4,   
    PTC0, PTA2,  
    PTC7, PTA1  
    );

BusIn inRows(
    PTB10,
    PTB11,
    PTE2,
    PTE3,
    PTE5 );

DigitalOut extLed(PTE4);

USBKeyboard kbd;

static int scanColumn(int col)
{
    int rowBits;
    // Drive output low to scan
    scanCols.write(0x3FFF ^ (1 << col));
    leds.write(col >> 1);
    wait(0.01);
    rowBits = inRows.read();
    scanCols.write(0x3FFF);
    // Inputs also active-low
    return rowBits ^ 0x1F;
}
    
int main()
{
    // Setup
    inRows.mode(PullUp);
    extLed = 1;

    // Run loop
    while(1)
    {
        int col, ocount;
        HID_REPORT report;
        
        report.data[0] = REPORT_ID_KEYBOARD;
        report.data[1] = 0; // modifiers
        report.data[2] = 0;
        ocount = 3;
        
        for (col=0; col < MAX_COLS; col++)
        {
            int row;
            int rowBits = scanColumn(col);
            if ( !rowBits )
              continue;
            
            for (row=0; row < MAX_ROWS; row++)
            {
              if ( rowBits & (1 << row) )
              {
                uint8_t key = hid_keys[col * MAX_ROWS + row];
                if ( IS_MODIFIER(key) )
                  report.data[1] |= MODIFIER_BIT(key);
                else if ( key != KEY_NONE )
                {
                  if ( ocount < REPORT_LEN )
                    report.data[ocount++] = key;
                }
                //kbd.printf("c%dr%d ", col, row);
              }
            }
        }

        while( ocount < REPORT_LEN )
          report.data[ocount++] = KEY_NONE;
            
        report.length = REPORT_LEN;  
        kbd.send(&report);
    }
}