Hallo!
Da ich nicht den originalen Post von Peter Dannegger verunstallten
wollte hier meine Frage dazu.
Ich habe den Code so umgeändert um ein 3x4 Keypad einzulesen.
Es hat 3 Spalten und 4 Zeilen.
Nun habe ich aber alle Pins auf einen Port gelegt. Kann das so gehen
oder kommt es da zum Kurzschluss?
Muss man die Richtung des Ports (Output/Input) vorher noch setzen?
1 | /* keyboard Interface:
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2 | * 4 rows x 3 columns: P0.0 - P0.3 * P2
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3 | * support multiple keys pressed simultaniously
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4 | * if more than two keys pressed, then every key need a decoupling diode
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5 | *
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6 | * 0x00 = no key changed
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7 | * 0x01 .. 0x0C = key released
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8 | * 0x81 .. 0x8C = key pressed
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9 | */
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10 |
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11 | /* P0 == PORTD
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12 | * PD0 COL 1
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13 | * PD1 COL 2
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14 | * PD2 COL 3
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15 |
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16 | * P2 == PIND
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17 | * PD3 ROW A
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18 | * PD4 ROW B
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19 | * PD5 ROW C
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20 | * PD6 ROW D
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21 | */
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22 |
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23 | //#pragma cd pl(9999)
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24 | #include <avr/io.h>
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25 |
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26 | #define idata
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27 | #define code
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28 |
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29 | #define P0 PORTD
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30 | #define P2 PIND
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31 |
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32 | #define KEY_PRESS_MASK 0x80
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33 |
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34 | #define nop() \
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35 | asm volatile ("nop")
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36 |
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37 | uint8_t n_keys_pressed; // 0, 1 or 2
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38 | static uint8_t idata valid_keys[3]; // last returned values
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39 | static uint8_t idata last_keys[3]; // t - 1
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40 |
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41 |
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42 | void InitKeyboard( void )
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43 | {
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44 | uint8_t i;
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45 |
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46 | for( i = 0; i < 3; ++i ){
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47 | valid_keys[i] = 0xFF; // low active
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48 | last_keys[i] = 0xFF;
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49 | }
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50 | n_keys_pressed = 0;
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51 | }
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52 |
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53 |
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54 | uint8_t GetKey( void ) // call with debouncing time (10..200msec)
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55 | {
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56 | uint8_t i, j;
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57 | uint8_t mask;
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58 | uint8_t key;
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59 | uint8_t column;
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60 | uint8_t key_nr = 0;
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61 | uint8_t code ROW[] = { ~0x08, ~0x10, ~0x20, ~0x40 }; // low active
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62 |
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63 | for( i = 0; i < 4; ++i ){
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64 |
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65 | P2 |= 0x07;
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66 | P0 &= ROW[i]; // set rows
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67 |
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68 | nop();
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69 |
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70 | column = P2; // read column
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71 |
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72 | if( column != valid_keys[i] && key_nr == 0 ){
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73 | for( mask = 1, j = 0; j < 3; mask <<= 1, j++ ){
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74 |
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75 | key = column & mask; // check bitwise
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76 |
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77 | if( key == (last_keys[i] & mask) ){ // debouncing
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78 |
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79 | if( key != (valid_keys[i] & mask) ){ // key not handled
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80 |
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81 | valid_keys[i] = valid_keys[i] & ~mask | key;
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82 | key_nr = 3 * i + j + 1; // 0x01 ... 0x0C
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83 |
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84 | if( key == 0 ){ // low active
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85 | n_keys_pressed++;
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86 | key_nr |= KEY_PRESS_MASK; // 0x81 ... 0x8C
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87 | }else{
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88 | n_keys_pressed--;
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89 | }
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90 | break;
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91 | }
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92 | }
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93 | }
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94 | }
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95 | last_keys[i] = column; // for next debouncing
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96 | }
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97 | return key_nr;
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98 | }
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Auch wie läuft das Entprellen ab? Muss ich in meiner Hauptschleife
sozusagen dann vor jedem Aufruf von KetKey ein Delay drinnen haben?
