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Viewing changes to src/rc-interface/motors.cc

  • Committer: Tim Marston
  • Date: 2014-01-15 22:18:56 UTC
  • Revision ID: tim@ed.am-20140115221856-lcqttlborwi7ot7k
rc-interface: mostly completed it (untested, but rx and tx code should work)

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src/rc-interface/motors.cc
 
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//
 
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// motor.cc
 
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//
 
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#include "motors.h"
 
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#include "config.h"
 
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#include <Arduino.h>
 
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#include <limits.h>
 
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void Motors::setup()
 
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{
 
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        // setup outputs
 
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        for( int pin = FIRST_PIN; pin < FIRST_PIN + NUM_CHANNELS; pin++ ) {
 
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                pinMode( pin, OUTPUT );
 
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                digitalWrite( pin, LOW );
 
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        }       
 
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}
 
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static signed long calculate_duration( unsigned long then, unsigned long now )
 
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{
 
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        // does it look like now has overflowed (and wrapped)?
 
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        if( now < then && now < ( ULONG_MAX / 2 ) && then > ( ULONG_MAX / 2 ) )
 
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                return now + ( ULONG_MAX - then );
 
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        // else, calculate duration
 
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        else
 
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                return now - then;
 
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}
 
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void Motors::update_channels( int channels[] )
 
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{
 
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        static int event = NUM_CHANNELS * 2;
 
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        unsigned long now = micros();
 
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        static unsigned long frame_start = now - FRAME_DURATION;
 
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        static unsigned long next_event_at;
 
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        if( now >= next_event_at )
 
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        {
 
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                // action event
 
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                digitalWrite( FIRST_PIN + ( event / 2 ), ( event & 1 )? LOW : HIGH );
 
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                // move to next event
 
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                if( ++event >= NUM_CHANNELS * 2 ) {
 
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                        event = 0;
 
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                        frame_start += FRAME_DURATION;
 
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                }
 
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                // calculate the time that the next event will occur
 
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                next_event_at = frame_start + ( event / 2 ) * CHANNEL_INTERVAL;
 
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                if( event & 1 )
 
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                        next_event_at += MIN_PULSE_WIDTH + channels[ event / 2 ] *
 
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                                ( MAX_PULSE_WIDTH - MIN_PULSE_WIDTH ) / MAX_CHANNEL_VALUE;
 
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//              Serial.print( event / 2 );
 
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//              Serial.print( ( event & 1 )? 'v' : '^' );
 
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//              Serial.print( " " );
 
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//              Serial.println( next_event_at );
 
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                if( event == 1 ) {
 
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                        unsigned long width = MIN_PULSE_WIDTH +
 
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                                (unsigned long)channels[ event / 2 ] *
 
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                                ( MAX_PULSE_WIDTH - MIN_PULSE_WIDTH ) / MAX_CHANNEL_VALUE;
 
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                        Serial.print( channels[ event / 2 ] );
 
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                        Serial.print( " " );
 
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                        Serial.println( width );
 
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                }
 
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        }
 
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}