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1932 | - | 1 | |
2 | // wi232.c: |
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3 | // |
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4 | // Call fopen_wi232() to set up the wi232 as an input output data stream. |
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5 | // If fopen_wi232() is the first fopen command called, then the wi232 |
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6 | // becomes stdin and stdout and stderr. |
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7 | // The |
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8 | // |
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9 | // Uses Interupts to handle data streaming. The wi232 uses USART0, which uses: |
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10 | // Rx = PORTE0 = pin 2 |
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11 | // Tx = PORTE1 = pin 3 |
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12 | // CTS = PORTE2 = pin 4 |
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13 | |||
14 | #include <inttypes.h> |
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15 | #include <stdio.h> |
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16 | #include <avr/io.h> |
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17 | #include <avr/interrupt.h> |
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18 | #include <avr/signal.h> |
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19 | |||
20 | #include "wi232.h" |
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21 | #include "circularqueue.h" |
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22 | #include "usart.h" |
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23 | |||
24 | const int _baud_rate_c = 38400; |
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25 | const int _tx_buffer_size_c = 256; |
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26 | const int _rx_buffer_size_c = 256; |
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27 | const uint8_t _cts_pin_c = _BV( PINE2 ); |
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28 | |||
29 | volatile char wi232_tx_buffer[ _tx_buffer_size_c ]; |
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30 | volatile char wi232_rx_buffer[ _rx_buffer_size_c ]; |
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31 | |||
32 | // circular queues used for the USART |
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33 | CircularQueue< volatile char > wi232_tx_q( wi232_tx_buffer, _tx_buffer_size_c ); |
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34 | CircularQueue< volatile char > wi232_rx_q( wi232_rx_buffer, _rx_buffer_size_c ); |
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35 | |||
36 | // prototype |
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37 | int wi232_putchar( char ); |
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38 | int wi232_getchar(); |
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39 | void initialize_baud_rate(); |
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40 | void command( bool enable ); |
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41 | void write_register( uint8_t reg, uint8_t value ); |
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42 | bool _cts(); |
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43 | |||
44 | // use BAUD_RATE baud 8N1 RX & TX on USART0 |
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45 | // to transmit to the wi232 |
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46 | FILE* fopen_wi232() |
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47 | { |
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48 | // enable Rx, Tx & Rx interupt |
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49 | // (Tx buffer empty interupt is enabled when we actually send something) |
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50 | UCSR0B = _BV( RXEN0 ) | |
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51 | _BV( TXEN0 ) | |
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52 | _BV( RXCIE0 ); |
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53 | |||
54 | // UCSC00 = 1 & UCSC01 = 1 -> 8-bit data |
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55 | UCSR0C = _BV( UCSZ00 ) | _BV( UCSZ01 ); |
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56 | |||
57 | initialize_baud_rate(); |
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58 | wi232_tx_q.clear(); |
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59 | wi232_rx_q.clear(); |
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60 | |||
61 | // set wi232_putchar as the stdout stream character Tx-er |
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62 | // set wi232_getchar as the stdin stream chacacter Rx-er |
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63 | return fdevopen( wi232_putchar, wi232_getchar, 0 ); |
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64 | } |
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65 | |||
66 | inline void initialize_baud_rate() |
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67 | { |
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68 | // enable command pin as output |
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69 | DDRE |= _BV( PORTE3 ); |
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70 | command( true ); |
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71 | usart0_set_baud_rate( 2400 ); |
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72 | sei(); |
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73 | write_register( 78, 3 ); // set baud rate to 38400 |
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74 | wait(100); |
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75 | cli(); |
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76 | usart0_set_baud_rate( 38400 ); |
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77 | command( false ); |
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78 | } |
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79 | |||
80 | inline void command( bool enable ) |
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81 | { |
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82 | if ( enable ) |
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83 | PORTE &= ~_BV( PORTE3 ); |
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84 | else |
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85 | PORTE |= _BV( PORTE3 ); |
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86 | } |
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87 | |||
88 | inline void write_register( uint8_t reg, uint8_t value ) |
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89 | { |
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90 | if ( value < 0x80 ) |
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91 | { |
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92 | // data = [ 0xFF, 2, reg, value ] |
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93 | wi232_putchar( 0xFF ); |
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94 | wi232_putchar( 2 ); |
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95 | wi232_putchar( reg ); |
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96 | wi232_putchar( value ); |
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97 | } |
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98 | else // value >= 0x80 |
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99 | { |
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100 | // data = [ 0xFF, 3, reg, 0xFE, (value - 0x80) ] |
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101 | wi232_putchar( 0xFF ); |
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102 | wi232_putchar( 3 ); |
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103 | wi232_putchar( reg ); |
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104 | wi232_putchar( 0xFE ); |
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105 | wi232_putchar( value - 0x80 ); |
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106 | } |
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107 | } |
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108 | |||
109 | int wi232_putchar( char x ) |
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110 | { |
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111 | wi232_tx_q.put( x ); |
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112 | |||
113 | // enable the "data register empty" interupt |
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114 | // (it may already be enabled in which case no harm is done) |
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115 | UCSR0B |= _BV( UDRIE0 ); |
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116 | |||
117 | // return -1 if overflow is true, otherwise return 0 |
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118 | // return wi232_tx_q.overflow() ? -1 : 0; |
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119 | return 0; // for now, screw overflow - just ignore it |
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120 | } |
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121 | |||
122 | int wi232_getchar() |
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123 | { |
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124 | // wait until the queue is no longer empty |
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125 | while ( wi232_rx_q.is_empty() ); |
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126 | |||
127 | char x = wi232_rx_q.get(); |
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128 | return x; |
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129 | } |
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130 | |||
131 | uint16_t wi232_data_available() |
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132 | { |
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133 | return wi232_rx_q.length(); |
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134 | } |
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135 | |||
136 | bool wi232_is_empty() |
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137 | { |
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138 | return wi232_rx_q.is_empty(); |
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139 | } |
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140 | |||
141 | // returns true when CTS is low, |
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142 | // i.e. it is true when it is okay to send data |
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143 | inline bool _cts() |
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144 | { |
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145 | return !(PINE & _cts_pin_c); |
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146 | } |
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147 | |||
148 | // we received some data on USART0 |
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149 | // put this data into the received data queue |
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150 | SIGNAL( SIG_UART0_RECV ) |
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151 | { |
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152 | wi232_rx_q.put( UDR0 ); |
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153 | } |
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154 | |||
155 | // the USART is ready to queue another byte to send |
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156 | SIGNAL( SIG_UART0_DATA ) |
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157 | { |
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158 | if ( !wi232_tx_q.is_empty() ) |
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159 | { |
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160 | if ( !_cts() ) |
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161 | { |
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162 | sei(); |
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163 | // wait until CTS is true |
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164 | while ( !_cts() ); |
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165 | } |
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166 | |||
167 | // if the queue is not empty, put the next character in the buffer |
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168 | // this also resets the interupt flag automatically |
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169 | UDR0 = wi232_tx_q.get(); |
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170 | } |
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171 | else |
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172 | { |
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173 | // disable the interupt |
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174 | UCSR0B &= ~_BV( UDRIE0 ); |
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175 | } |
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176 | } |
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177 |