main.cpp

00001 #include "mbed.h"
00002 
00003 BusInOut colBus( p26, p25, p24);
00004 const PinName rowPins[] = { p30, p29, p28, p27 };
00005 
00006 volatile bool irqFinished = false;
00007 
00008 inline char toChar( unsigned char r, unsigned char c) {
00009     static const char keytable[] = { '1', '2', '3', 'A',
00010                                      '4', '5', '6', 'B',
00011                                      '7', '8', '9', 'C',
00012                                      '*', '0', '#', 'D'
00013                                    };
00014     return keytable[r*4+c];
00015 }
00016 
00017 inline char toBinary( unsigned char r, unsigned char c) {
00018     static const char keytable[] = { 0x1, 0x2, 0x3, 0xC,
00019                                      0x4, 0x5, 0x6, 0xD,
00020                                      0x7, 0x8, 0x9, 0xE,
00021                                      0xA, 0x0, 0xB, 0xF
00022                                    };
00023     return keytable[r*4+c];
00024 }
00025 
00026 inline void start() {
00027     colBus.output();
00028     colBus = 0xF;
00029 }
00030 
00031 // simple log2, only 4bits needed
00032 inline unsigned char _lg2( unsigned char c) {
00033     return c&1 ? 0 : c&2 ? 1 : c&4 ? 2 : 3;
00034 }
00035 
00036 inline char pin2Row(PinName pin) {
00037     return rowPins[0] == pin ? 0 : rowPins[1] == pin ? 1 : rowPins[2] == pin ? 2 : 3;
00038 }
00039 
00040 BusOut code(LED4, LED3, LED2, LED1); //show binary code of key
00041 
00042 void checkColumn(PinName pinPressed) {
00043     {   //debounce
00044         DigitalIn in(pinPressed);
00045         for (char c=0; c<100; ++c) {
00046             if ( !in.read()) {
00047                 irqFinished=true;
00048                 return;  // key not long enough pressed
00049             }
00050             wait_us(100);
00051         }
00052     }
00053     // check column
00054     DigitalOut p(pinPressed);
00055     p = 0x1;
00056     colBus.input();
00057     unsigned char col = colBus.read();
00058     if (col) {
00059         col = _lg2(col);
00060         {   // blink to show key pressed
00061             code = 0;
00062             wait_ms(150);
00063             code = 0xF;
00064             wait_ms(150);
00065         }
00066         char row = pin2Row(pinPressed);
00067         code = toBinary(row,col);
00068 //        printf("%d, %d, %c\r\n", row, col, toChar(row,col));
00069     }
00070     irqFinished = true;
00071 }
00072 
00073 void trigger27() {
00074     checkColumn(p27);
00075 }
00076 void trigger28() {
00077     checkColumn(p28);
00078 }
00079 void trigger29() {
00080     checkColumn(p29);
00081 }
00082 void trigger30() {
00083     checkColumn(p30);
00084 }
00085 
00086 void checkRow() {
00087     InterruptIn irqIn27(p27), irqIn28(p28), irqIn29(p29), irqIn30(p30);
00088     irqIn27.rise( &trigger27);
00089     irqIn28.rise( &trigger28);
00090     irqIn29.rise( &trigger29);
00091     irqIn30.rise( &trigger30);
00092 }
00093 
00094 int main() {
00095     while (1) {
00096         start();
00097         irqFinished = false;
00098         checkRow();
00099         while (!irqFinished);
00100     }
00101 }