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  • Committer: Tim Marston
  • Date: 2013-11-20 23:58:23 UTC
  • Revision ID: tim@ed.am-20131120235823-q9xheffre1y00lhd
fixed pulse-width test

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test/receiver/pulse-width/main.ino
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// This program tries to measure the width of the signal pulses in
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// microseconds.  It takes several measurements and prints it the average over
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// serial.
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//
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// NOTES: Due to the way our receiver works (by varying the position of the
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// rising edge of the pulse and keeping the falling edge fixed), it is
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// sufficient for us to measure the pule width to determine the channel value
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// (e.g., throttle position).  But it should be noted that this relies on a
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// quirk of our receiver/transmitter and it is not truly measuring PPM.  Our
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// next experiment is measuring PPM (../ppm-read).
 
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// number of signal pulses to average
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#define AVERAGE_SAMPLES 1
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#define AVERAGE_DAMP 1
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// graphic display
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#define GRAPH 1
 
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#define GRAPH 0
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#define GRAPH_MIN 1000
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#define GRAPH_MAX 2000
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#define GRAPH_SIZE 30
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        for( int a = 0; a < AVERAGE_SAMPLES; a++ )
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                intervals[ a ] = 0;
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#ifdef GRAPH
 
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#if GRAPH
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        // init graph
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        char graph[ GRAPH_SIZE + 3 ];
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        for( int a = 1; a < GRAPH_SIZE + 1; a++ )
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        while( true )
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        {
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                // detect pulse falling-edge
 
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                noInterrupts();
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                unsigned long pulse_on = _new_pulse_on;
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                unsigned long pulse_off = _new_pulse_off;
 
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                interrupts();
 
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                bool got_pulse = false;
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                if( pulse_off > last_pulse_off )
 
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                if( pulse_off != last_pulse_off )
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                {
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                        // sanity check
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                        unsigned long interval = pulse_off - pulse_on;
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                        if( interval > 800 && interval < 3000 )
 
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//                      if( interval > 800 && interval < 3000 )
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                        {
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                                // update interval buffer
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                                intervals[ interval_idx ] = pulse_off - pulse_on;
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                                ave += intervals[ a ];
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                        ave /= AVERAGE_SAMPLES;
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#ifdef GRAPH
 
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#if GRAPH
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                        // draw graph
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                        int pos = ( GRAPH_SIZE ) *