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  • Committer: Tim Marston
  • Date: 2012-11-28 23:18:38 UTC
  • Revision ID: tim@ed.am-20121128231838-r2t1dyawkzb6nxhe
initial commit, and a couple of receiver test programs

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test/receiver/pulse-width/main.ino
 
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//
 
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// main.ino
 
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//
 
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// Testing reading from the receiver.  We're expecting a PWM signal, on
 
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// interrupt 0 (which is pin 2 on an Arduino Uno).
 
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//
 
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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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// number of signal pulses to average
 
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#define SIGNAL_SAMPLES 10
 
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// set to the time that the last signal pulse was at
 
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static unsigned long _new_pulse_on = 0;
 
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static unsigned long _new_pulse_off = 0;
 
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// ISR to handle the PWM signal
 
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void signal_handler()
 
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{
 
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        // record time
 
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        if( digitalRead( 2 ) )
 
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                _new_pulse_on = micros();
 
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        else
 
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                _new_pulse_off = micros();
 
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}
 
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void setup()
 
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{
 
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        // set up an interrupt handler on pin 2
 
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        attachInterrupt( 0, signal_handler, CHANGE );
 
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        digitalWrite( 2, LOW );
 
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        Serial.begin( 9600 );
 
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}
 
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void loop()
 
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{
 
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        unsigned long last_pulse = 0;
 
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        unsigned long intervals[ SIGNAL_SAMPLES ] = {0};
 
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        int interval_idx = 0;
 
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        while( true )
 
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        {
 
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                // detect pulse falling-edge
 
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                unsigned long new_pulse_on = _new_pulse_on;
 
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                unsigned long new_pulse_off = _new_pulse_off;
 
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                bool got_pulse = false;
 
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                if( new_pulse_off > last_pulse )
 
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                {
 
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                        // update interval buffer
 
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                        intervals[ interval_idx ] = new_pulse_off - new_pulse_on;
 
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                        if( ++interval_idx >= SIGNAL_SAMPLES )
 
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                                interval_idx = 0;
 
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                        last_pulse = new_pulse_off;
 
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                        got_pulse = true;
 
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                }
 
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                // display average?
 
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                if( interval_idx == 0 && got_pulse )
 
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                {
 
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                        // calculate average
 
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                        double ave = 0;
 
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                        for( int a = 0; a < SIGNAL_SAMPLES; a++ )
 
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                                ave += intervals[ a ];
 
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                        ave /= SIGNAL_SAMPLES;
 
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                        // tell it like it is
 
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                        Serial.println( round( ave ) );
 
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                }               
 
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        }
 
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}