uartsw_8c-source.html

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00186             <span class="comment">// shift bits down</span>
00187             UartswTxData = UartswTxData&gt;&gt;1;
00188         }
00189         <span class="keywordflow">else</span>
00190         {
00191             <span class="comment">// transmit stop bit</span>
00192 <span class="preprocessor">            #ifdef UARTSW_INVERT</span>
00193 <span class="preprocessor"></span>            cbi(<a class="code" href="uartsw2conf_8h.html#a2">UARTSW_TX_PORT</a>, <a class="code" href="uartsw2conf_8h.html#a4">UARTSW_TX_PIN</a>);
00194 <span class="preprocessor">            #else</span>
00195 <span class="preprocessor"></span>            sbi(<a class="code" href="uartsw2conf_8h.html#a2">UARTSW_TX_PORT</a>, <a class="code" href="uartsw2conf_8h.html#a4">UARTSW_TX_PIN</a>);
00196 <span class="preprocessor">            #endif</span>
00197 <span class="preprocessor"></span>        }
00198         <span class="comment">// schedule the next bit</span>
00199         outw(OCR1A, inw(OCR1A) + UartswBaudRateDiv);
00200         <span class="comment">// count down</span>
00201         UartswTxBitNum--;
00202     }
00203     <span class="keywordflow">else</span>
00204     {
00205         <span class="comment">// transmission is done</span>
00206         <span class="comment">// clear busy flag</span>
00207         UartswTxBusy = FALSE;
00208     }
00209 }
00210 
<a name="l00211"></a><a class="code" href="uartsw2_8h.html#a8">00211</a> <span class="keywordtype">void</span> <a class="code" href="uartsw_8c.html#a17">uartswRxBitService</a>(<span class="keywordtype">void</span>)
00212 {
00213     <span class="comment">// this function runs on either:</span>
00214     <span class="comment">// - a rising edge interrupt</span>
00215     <span class="comment">// - OC1B</span>
00216     <span class="keywordflow">if</span>(!UartswRxBusy)
00217     {
00218         <span class="comment">// this is a start bit</span>
00219         <span class="comment">// disable ICP interrupt</span>
00220         cbi(TIMSK, TICIE1);
00221         <span class="comment">// schedule data bit sampling 1.5 bit periods from now</span>
00222         outw(OCR1B, inw(TCNT1) + UartswBaudRateDiv + UartswBaudRateDiv/2);
00223         <span class="comment">// clear OC1B interrupt flag</span>
00224         sbi(TIFR, OCF1B);
00225         <span class="comment">// enable OC1B interrupt</span>
00226         sbi(TIMSK, OCIE1B);
00227         <span class="comment">// set start bit flag</span>
00228         UartswRxBusy = TRUE;
00229         <span class="comment">// reset bit counter</span>
00230         UartswRxBitNum = 0;
00231         <span class="comment">// reset data</span>
00232         UartswRxData = 0;
00233     }
00234     <span class="keywordflow">else</span>
00235     {
00236         <span class="comment">// start bit has already been received</span>
00237         <span class="comment">// we're in the data bits</span>
00238         
00239         <span class="comment">// shift data byte to make room for new bit</span>
00240         UartswRxData = UartswRxData&gt;&gt;1;
00241 
00242         <span class="comment">// sample the data line</span>
00243 <span class="preprocessor">        #ifdef UARTSW_INVERT</span>
00244 <span class="preprocessor"></span>        <span class="keywordflow">if</span>( !(inb(<a class="code" href="uartsw2conf_8h.html#a7">UARTSW_RX_PORTIN</a>) &amp; (1&lt;&lt;<a class="code" href="uartsw2conf_8h.html#a8">UARTSW_RX_PIN</a>)) )
00245 <span class="preprocessor">        #else</span>
00246 <span class="preprocessor"></span>        <span class="keywordflow">if</span>( !(inb(<a class="code" href="uartsw2conf_8h.html#a7">UARTSW_RX_PORTIN</a>) &amp; (1&lt;&lt;<a class="code" href="uartsw2conf_8h.html#a8">UARTSW_RX_PIN</a>)) )
00247 <span class="preprocessor">        #endif</span>
00248 <span class="preprocessor"></span>        {
00249             <span class="comment">// serial line is marking</span>
00250             <span class="comment">// record '1' bit</span>
00251             UartswRxData |= 0x80;
00252         }
00253 
00254         <span class="comment">// increment bit counter</span>
00255         UartswRxBitNum++;
00256         <span class="comment">// schedule next bit sample</span>
00257         outw(OCR1B, inw(OCR1B) + UartswBaudRateDiv);
00258 
00259         <span class="comment">// check if we have a full byte</span>
00260         <span class="keywordflow">if</span>(UartswRxBitNum &gt;= 8)
00261         {
00262             <span class="comment">// save data in receive buffer</span>
00263             <a class="code" href="group__buffer.html#ga5">bufferAddToEnd</a>(&amp;uartswRxBuffer, UartswRxData);
00264             <span class="comment">// disable OC1B interrupt</span>
00265             cbi(TIMSK, OCIE1B);
00266             <span class="comment">// clear ICP interrupt flag</span>
00267             sbi(TIFR, ICF1);
00268             <span class="comment">// enable ICP interrupt</span>
00269             sbi(TIMSK, TICIE1);
00270             <span class="comment">// clear start bit flag</span>
00271             UartswRxBusy = FALSE;
00272         }
00273     }
00274 }
00275 
00276 <span class="comment">/*</span>
00277 <span class="comment">void uartswRxBitService(void)</span>
00278 <span class="comment">{</span>
00279 <span class="comment">    u16 thisBitTime;</span>
00280 <span class="comment">    u08 bitperiods;</span>
00281 <span class="comment">    u08 i;</span>
00282 <span class="comment"></span>
00283 <span class="comment">    // bit transition was detected</span>
00284 <span class="comment">    // record bit's edge time</span>
00285 <span class="comment">    thisBitTime = inw(ICR1);</span>
00286 <span class="comment"></span>
00287 <span class="comment">    cbi(PORTB, 0);</span>
00288 <span class="comment"></span>
00289 <span class="comment">    if(!UartswRxStartBit)</span>
00290 <span class="comment">    {</span>
00291 <span class="comment">        // this is a start bit</span>
00292 <span class="comment">        // switch to falling-edge trigger</span>
00293 <span class="comment">        cbi(TCCR1B, ICES1);</span>
00294 <span class="comment">        // record bit time</span>
00295 <span class="comment">        UartswRxBitTime = thisBitTime;</span>
00296 <span class="comment">        // set start bit flag</span>
00297 <span class="comment">        UartswRxStartBit = TRUE;</span>
00298 <span class="comment">        // reset bit counter</span>
00299 <span class="comment">        UartswRxBitNum = 0;</span>
00300 <span class="comment">        // reset data</span>
00301 <span class="comment">        UartswRxData = 0;</span>
00302 <span class="comment">    }</span>
00303 <span class="comment">    else</span>
00304 <span class="comment">    {</span>
00305 <span class="comment">        // start bit has already been received</span>
00306 <span class="comment">        // we're in the data bits</span>
00307 <span class="comment">        </span>
00308 <span class="comment">        // how many bit periods since last edge?</span>
00309 <span class="comment">        bitperiods = (thisBitTime - UartswRxBitTime + UartswBaudRateDiv/2)/UartswBaudRateDiv;</span>
00310 <span class="comment">        // set last edge time</span>
00311 <span class="comment">        UartswRxBitTime = thisBitTime;</span>
00312 <span class="comment"></span>
00313 <span class="comment">        if(bitperiods &gt; 10)</span>
00314 <span class="comment">        {</span>
00315 <span class="comment">            // switch to trigger on rising edge</span>
00316 <span class="comment">            sbi(TCCR1B, ICES1);</span>
00317 <span class="comment">            // clear start bit flag</span>
00318 <span class="comment">            UartswRxStartBit = FALSE;</span>
00319 <span class="comment">        }</span>
00320 <span class="comment">        else</span>
00321 <span class="comment">        {</span>
00322 <span class="comment"></span>
00323 <span class="comment"></span>
00324 <span class="comment">        if( inb(TCCR1B) &amp; (1&lt;&lt;ICES1) )</span>
00325 <span class="comment">        {</span>
00326 <span class="comment">            // just triggered on a rising edge</span>
00327 <span class="comment">            // previous bits were zero</span>
00328 <span class="comment">            // shift in the data (data bits are inverted)</span>
00329 <span class="comment">            for(i=0; i&lt;bitperiods; i++)</span>
00330 <span class="comment">            {</span>
00331 <span class="comment">                UartswRxData = UartswRxData&lt;&lt;1;</span>
00332 <span class="comment">                UartswRxData |= 0x01;</span>
00333 <span class="comment">            }</span>
00334 <span class="comment">            // switch to trigger on falling edge</span>
00335 <span class="comment">            cbi(TCCR1B, ICES1);</span>
00336 <span class="comment">        }</span>
00337 <span class="comment">        else</span>
00338 <span class="comment">        {</span>
00339 <span class="comment">            // just triggered on a falling edge</span>
00340 <span class="comment">            // previous bits were one</span>
00341 <span class="comment">            // shift in the data (data bits are inverted)</span>
00342 <span class="comment">            for(i=0; i&lt;bitperiods; i++)</span>
00343 <span class="comment">            {</span>
00344 <span class="comment">                UartswRxData = UartswRxData&lt;&lt;1;</span>
00345 <span class="comment">            }</span>
00346 <span class="comment">            // switch to trigger on rising edge</span>
00347 <span class="comment">            sbi(TCCR1B, ICES1);</span>
00348 <span class="comment">        }</span>
00349 <span class="comment">        </span>
00350 <span class="comment">        // increment bit counter</span>
00351 <span class="comment">        UartswRxBitNum += bitperiods;</span>
00352 <span class="comment">        </span>
00353 <span class="comment">        // check if we have a full byte + start bit</span>
00354 <span class="comment">        if(bitperiods &gt; 8)</span>
00355 <span class="comment">        {</span>
00356 <span class="comment">            // save data in receive buffer</span>
00357 <span class="comment">            bufferAddToEnd(&amp;uartswRxBuffer, UartswRxData);</span>
00358 <span class="comment">            // switch to trigger on rising edge</span>
00359 <span class="comment">            sbi(TCCR1B, ICES1);</span>
00360 <span class="comment">            // clear start bit flag</span>
00361 <span class="comment">            UartswRxStartBit = FALSE;</span>
00362 <span class="comment">        }</span>
00363 <span class="comment">        }</span>
00364 <span class="comment">    }</span>
00365 <span class="comment"></span>
00366 <span class="comment">    // turn off debug LEDs</span>
00367 <span class="comment">    delay(10);</span>
00368 <span class="comment">    sbi(PORTB, 0);</span>
00369 <span class="comment">    sbi(PORTB, 1);</span>
00370 <span class="comment">}</span>
00371 <span class="comment">*/</span>
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