1 | /*******************Includes*************************************/
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2 |
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3 | #include <avr/io.h>
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4 | #include <stdio.h>
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5 | #include <stdbool.h>
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6 |
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7 |
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8 |
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9 | /******************Macros and Defines*********************/
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10 |
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11 | #define BAUD 19200
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12 | #define MYUBRR F_CPU/16/BAUD-1
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13 |
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14 |
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15 |
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16 | /**************Function Prototypes*********************************/
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17 |
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18 | void usart_init(uint16_t ubrr);
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19 | char usart_getchar( void );
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20 | void usart_putchar( char data );
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21 | void usart_pstr (char *s);
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22 | unsigned char usart_kbhit(void);
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23 |
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24 |
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25 |
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26 | /*******************Main***********************/
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27 |
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28 | int main( void ) {
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29 |
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30 | // configure PORTA as output
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31 |
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32 | DDRA = 0xFF;
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33 |
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34 | // setup PORTB data direction as an input
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35 |
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36 | DDRB = 0;
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37 |
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38 | // make sure it is high impedance and will not source
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39 |
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40 | PORTB = 0;
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41 |
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42 | // fire up the usart
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43 |
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44 | usart_init ( MYUBRR );
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45 |
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46 | // dump some strings to the screen at power on
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47 |
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48 | usart_pstr("Ready to rock and roll!\n\r");
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49 | usart_pstr("Type in a character, and I will transpose it up by 1:\n\r");
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50 |
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51 | // main loop
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52 |
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53 | while(true) {
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54 |
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55 | // if a key has been pressed, then process it
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56 |
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57 | if(usart_kbhit()) {
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58 | usart_putchar(usart_getchar() + 1);
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59 | }
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60 |
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61 |
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62 | // map the PINB inputs to the PORTA outputs
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63 |
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64 | PORTA = PINB;
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65 |
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66 |
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67 |
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68 | // a little humor is always good, PB0 gets the user yelled at
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69 |
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70 | if(bit_is_clear(PINB,PB0)) {
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71 |
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72 | usart_pstr("OUCH! Stop poking me!\n\r");
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73 | }
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74 | }
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75 | }
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76 | /*****************usart Related****************/
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77 |
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78 | void usart_init( uint16_t ubrr) {
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79 |
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80 | // Set baud rate
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81 |
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82 | UBRRH = (uint8_t)(ubrr>>8);
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83 | UBRRL = (uint8_t)ubrr;
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84 |
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85 | // Enable receiver and transmitter
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86 |
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87 | UCSRB = (1<<RXEN)|(1<<TXEN);
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88 |
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89 | // Set frame format: 8data, 1stop bit
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90 |
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91 | UCSRC = (1<<URSEL)|(3<<UCSZ0);
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92 | }
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93 |
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94 | void usart_putchar(char data) {
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95 |
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96 | // Wait for empty transmit buffer
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97 |
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98 | while ( !(UCSRA & (_BV(UDRE))) );
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99 |
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100 | // Start transmission
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101 |
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102 | UDR = data;
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103 | }
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104 | char usart_getchar(void) {
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105 |
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106 | // Wait for incoming data
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107 |
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108 | while ( !(UCSRA & (_BV(RXC))) );
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109 |
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110 | // Return the data
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111 |
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112 | return UDR;
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113 | }
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114 |
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115 | unsigned char usart_kbhit(void) {
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116 |
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117 | //return nonzero if char waiting polled version
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118 |
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119 | unsigned char b;
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120 | b=0;
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121 | if(UCSRA & (1<<RXC)) b=1;
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122 | return b;
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123 | }
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124 |
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125 | void usart_pstr(char *s) {
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126 |
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127 | // loop through entire string
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128 |
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129 | while (*s) {
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130 | usart_putchar(*s);
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131 | s++;
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132 | }
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133 | }
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