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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 1920 | - | 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 |