uartsw2_8c-source.html

ATMEL的AVR单片机库文件

00143     <span class="comment">// save data</span>
00144     UartswTxData = data;
00145     <span class="comment">// set number of bits (+1 for stop bit)</span>
00146     UartswTxBitNum = 9;
00147     
00148     <span class="comment">// set the start bit</span>
00149     sbi(<a class="code" href="uartsw2conf_8h.html#a1">UARTSW_TX_PORT</a>, <a class="code" href="uartsw2conf_8h.html#a3">UARTSW_TX_PIN</a>);
00150     <span class="comment">// schedule the next bit</span>
00151     outb(OCR2, inb(TCNT2) + UartswBaudRateDiv);
00152     <span class="comment">// enable OC2 interrupt</span>
00153     sbi(TIMSK, OCIE2);
00154 }
00155 <span class="comment"></span>
00156 <span class="comment">//! gets a byte (if available) from the uart receive buffer</span>
<a name="l00157"></a><a class="code" href="uartsw2_8c.html#a15">00157</a> <span class="comment"></span>u08 <a class="code" href="uartsw2_8h.html#a6">uartswReceiveByte</a>(u08* rxData)
00158 {
00159     <span class="comment">// make sure we have a receive buffer</span>
00160     <span class="keywordflow">if</span>(uartswRxBuffer.size)
00161     {
00162         <span class="comment">// make sure we have data</span>
00163         <span class="keywordflow">if</span>(uartswRxBuffer.datalength)
00164         {
00165             <span class="comment">// get byte from beginning of buffer</span>
00166             *rxData = <a class="code" href="buffer_8h.html#a2">bufferGetFromFront</a>(&amp;uartswRxBuffer);
00167             <span class="keywordflow">return</span> TRUE;
00168         }
00169         <span class="keywordflow">else</span>
00170         {
00171             <span class="comment">// no data</span>
00172             <span class="keywordflow">return</span> FALSE;
00173         }
00174     }
00175     <span class="keywordflow">else</span>
00176     {
00177         <span class="comment">// no buffer</span>
00178         <span class="keywordflow">return</span> FALSE;
00179     }
00180 }
00181 
<a name="l00182"></a><a class="code" href="uartsw2_8c.html#a16">00182</a> <span class="keywordtype">void</span> <a class="code" href="uartsw_8c.html#a16">uartswTxBitService</a>(<span class="keywordtype">void</span>)
00183 {
00184     <span class="keywordflow">if</span>(UartswTxBitNum)
00185     {
00186         <span class="comment">// there are bits still waiting to be transmitted</span>
00187         <span class="keywordflow">if</span>(UartswTxBitNum &gt; 1)
00188         {
00189             <span class="comment">// transmit data bits (inverted, LSB first)</span>
00190             <span class="keywordflow">if</span>( !(UartswTxData &amp; 0x01) )
00191                 sbi(<a class="code" href="uartsw2conf_8h.html#a1">UARTSW_TX_PORT</a>, <a class="code" href="uartsw2conf_8h.html#a3">UARTSW_TX_PIN</a>);
00192             <span class="keywordflow">else</span>
00193                 cbi(<a class="code" href="uartsw2conf_8h.html#a1">UARTSW_TX_PORT</a>, <a class="code" href="uartsw2conf_8h.html#a3">UARTSW_TX_PIN</a>);
00194             <span class="comment">// shift bits down</span>
00195             UartswTxData = UartswTxData&gt;&gt;1;
00196         }
00197         <span class="keywordflow">else</span>
00198         {
00199             <span class="comment">// transmit stop bit</span>
00200             cbi(<a class="code" href="uartsw2conf_8h.html#a1">UARTSW_TX_PORT</a>, <a class="code" href="uartsw2conf_8h.html#a3">UARTSW_TX_PIN</a>);
00201         }
00202         <span class="comment">// schedule the next bit</span>
00203         outb(OCR2, inb(OCR2) + UartswBaudRateDiv);
00204         <span class="comment">// count down</span>
00205         UartswTxBitNum--;
00206     }
00207     <span class="keywordflow">else</span>
00208     {
00209         <span class="comment">// transmission is done</span>
00210         <span class="comment">// clear busy flag</span>
00211         UartswTxBusy = FALSE;
00212         <span class="comment">// disable OC2 interrupt</span>
00213         cbi(TIMSK, OCIE2);
00214     }
00215 }
00216 
<a name="l00217"></a><a class="code" href="uartsw2_8c.html#a17">00217</a> <span class="keywordtype">void</span> <a class="code" href="uartsw_8c.html#a17">uartswRxBitService</a>(<span class="keywordtype">void</span>)
00218 {
00219     <span class="comment">// this function runs on either:</span>
00220     <span class="comment">// - a rising edge interrupt</span>
00221     <span class="comment">// - Timer 0 output compare</span>
00222     <span class="keywordflow">if</span>(!UartswRxBusy)
00223     {
00224         <span class="comment">// UART was not previously busy,</span>
00225         <span class="comment">// this must be is a start bit</span>
00226         
00227         <span class="comment">// disable INT2 interrupt</span>
00228         cbi(GICR, INT2);
00229         <span class="comment">// schedule data bit sampling 1.5 bit periods from now</span>
00230         outb(OCR0, inb(TCNT0) + UartswBaudRateDiv + UartswBaudRateDiv/2);
00231         <span class="comment">// clear OC0 interrupt flag</span>
00232         sbi(TIFR, OCF0);
00233         <span class="comment">// enable OC0 interrupt</span>
00234         sbi(TIMSK, OCIE0);
00235         <span class="comment">// set busy flag</span>
00236         UartswRxBusy = TRUE;
00237         <span class="comment">// reset bit counter</span>
00238         UartswRxBitNum = 0;
00239         <span class="comment">// reset data</span>
00240         UartswRxData = 0;
00241     }
00242     <span class="keywordflow">else</span>
00243     {
00244         <span class="comment">// start bit has already been received</span>
00245         <span class="comment">// we're in the data bits</span>
00246         
00247         <span class="comment">// shift data byte to make room for new bit</span>
00248         UartswRxData = UartswRxData&gt;&gt;1;
00249 
00250         <span class="comment">// sample the data line</span>
00251         <span class="keywordflow">if</span>( !(inb(<a class="code" href="uartsw2conf_8h.html#a6">UARTSW_RX_PORTIN</a>) &amp; (1&lt;&lt;<a class="code" href="uartsw2conf_8h.html#a7">UARTSW_RX_PIN</a>)) )
00252         {
00253             <span class="comment">// serial line is low</span>
00254             <span class="comment">// record '1' bit (data inverted)</span>
00255             UartswRxData |= 0x80;
00256         }
00257 
00258         <span class="comment">// increment bit counter</span>
00259         UartswRxBitNum++;
00260         <span class="comment">// schedule next bit sample</span>
00261         outb(OCR0, inb(OCR0) + UartswBaudRateDiv);
00262 
00263         <span class="comment">// check if we have a full byte</span>
00264         <span class="keywordflow">if</span>(UartswRxBitNum &gt;= 8)
00265         {
00266             <span class="comment">// save data in receive buffer</span>
00267             <a class="code" href="buffer_8h.html#a5">bufferAddToEnd</a>(&amp;uartswRxBuffer, UartswRxData);
00268             <span class="comment">// disable OC0 interrupt</span>
00269             cbi(TIMSK, OCIE0);
00270             <span class="comment">// clear INT2 interrupt flag</span>
00271             sbi(GIFR, INTF2);
00272             <span class="comment">// enable INT interrupt</span>
00273             sbi(GICR, INT2);
00274             <span class="comment">// clear busy flag</span>
00275             UartswRxBusy = FALSE;
00276         }
00277     }
00278 }
00279 
00280 <a class="code" href="a2d_8c.html#a10">SIGNAL</a>(SIG_INTERRUPT2)
00281 {
00282     <span class="comment">// run RxBit service routine</span>
00283     <a class="code" href="uartsw_8c.html#a17">uartswRxBitService</a>();
00284 }
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