/elec/propeller-clock

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bzr branch http://bzr.ed.am/elec/propeller-clock
13 by edam
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/*
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 * propeller-clock.ino
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 *
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 * Copyright (C) 2011 Tim Marston <tim@ed.am> and Dan Marston.
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 *
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 * This file is part of propeller-clock (hereafter referred to as "this
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 * program"). See http://ed.am/dev/software/arduino/propeller-clock for more
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 * information.
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 *
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 * This program is free software: you can redistribute it and/or modify
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 * it under the terms of the GNU Lesser General Public License as published
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 * by the Free Software Foundation, either version 3 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public License
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 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
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 */
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/******************************************************************************
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Set up:
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 * a PC fan is wired up to a 12V power supply
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 * the fan's SENSE (tachiometer) pin connected to pin 2 on the
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   arduino.
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 * the pins 4 to 13 on the arduino should directly drive an LED (the
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   LED on pin 4 is in the centre of the clock face and the LED on pin
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   13 is at the outside.
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 * if a longer hand (and a larger clock face) is desired, pin 4 can be
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   used to indirectly drive a transistor which in turn drives several
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   LEDs that turn on anf off in unison in the centre of the clock.
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 * a button should be attached to pin 3 that grounds it when pressed.
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 * A DS1307 remote clock is connected via I2C on analog pins 4 and 5.
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Implementation details:
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 * for a schematic, see ../project/propeller-clock.sch.
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 * the timing of the drawing of the clock face is recalculated with
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   every rotation of the propeller.
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 * a PC fan actually sends 2 tachiometer pulses per revolution, so the
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   software skips every other one. This means that the clock may
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   appear upside-down if started with the propeller in the wrong
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   position. You will need to experiment to dicsover the position that
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   the propeller must be in when starting the clock.
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Usage instructions:
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 * pressing the button cycles between variations of the current
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   display mode.
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 * pressing and holding the button for a second cycles between display
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   modes (e.g., analogue and digital).
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 * pressing and holding the button for 5 seconds enters "time set"
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   mode. In this mode, the following applies:
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    - the field that is being set flashes
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    - pressing the button increments the field currently being set
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    - pressing and holding the button for a second cycles through the
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      fields that can be set
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    - pressing and holding the button for 5 seconds sets the time and
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      exits "time set" mode
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******************************************************************************/
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#include <Bounce.h>
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#include <DS1307.h>
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#include <Wire.h>
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//_____________________________________________________________________________
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//                                                                         data
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// when non-zero, the time (in microseconds) of a new fan pulse that
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// has just occurred, which means that segment drawing needs to be
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// restarted
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static unsigned long new_pulse_at = 0;
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// the time (in microseconds) when the last fan pulse occurred
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static unsigned long last_pulse_at = 0;
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// duration (in microseconds) that a segment should be displayed
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static unsigned long segment_step = 0;
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// remainder after divisor and a tally of the remainders for each segment
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static unsigned long segment_step_sub_step = 0;
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static unsigned long segment_step_sub = 0;
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// flag to indicate that the drawing mode should be cycled to the next one
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static bool inc_draw_mode = false;
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// a bounce-managed button
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static Bounce button( 3, 50 );
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// the time
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static int time_hours = 0;
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static int time_minutes = 0;
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static int time_seconds = 0;
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// number of segments in a full display (rotation) is 60 (one per
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// second) times the desired number of sub-divisions of a second
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#define NUM_SECOND_SEGMENTS 5
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#define NUM_SEGMENTS ( 60 * NUM_SECOND_SEGMENTS )
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//_____________________________________________________________________________
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//                                                                         code
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// check for button presses
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void checkButtons()
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{
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	// update buttons
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	button.update();
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	// notice button presses
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	if( button.risingEdge() )
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		inc_draw_mode = true;
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}
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// keep track of time
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void trackTime()
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{
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	// previous time and any carried-over milliseconds
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	static unsigned long last_time = millis();
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	static unsigned long carry = 0;
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	// how many milliseonds have elapsed since we last checked?
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	unsigned long next_time = millis();
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	unsigned long delta = next_time - last_time + carry;
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	// update the previous time and carried-over milliseconds
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	last_time = next_time;
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	carry = delta % 1000;
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	// add the seconds that have passed to the time
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	time_seconds += delta / 1000;
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	while( time_seconds >= 60 ) {
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		time_seconds -= 60;
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		time_minutes++;
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		if( time_minutes >= 60 ) {
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			time_minutes -= 60;
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			time_hours++;
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			if( time_hours >= 24 )
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				time_hours -= 24;
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		}
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	}
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}
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// turn an led on/off
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void ledOn( int num, bool on )
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{
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	if( num < 0 || num > 9 ) return;
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	// convert to pin no.
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	num += 4;
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	// pin 4 needs to be inverted (it's driving a PNP)
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	if( num == 4 ) on = !on;
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	digitalWrite( num, on? HIGH : LOW );
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}
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// draw a segment for the test display
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void drawNextSegment_test( bool reset )
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{
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	// keep track of segment
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	static unsigned int segment = 0;
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	if( reset ) segment = 0;
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	segment++;
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	// turn on inside and outside LEDs
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	ledOn( 0, true );
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	ledOn( 9, true );
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	// display segment number in binary across in the inside LEDs,
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	// with the LED on pin 12 showing the least-significant bit
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	for( int a = 0; a < 8; a++ )
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		ledOn( 8 - a, ( segment >> a ) & 1 );
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}
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// draw a segment for the time display
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void drawNextSegment_time( bool reset )
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{
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	static int second = 0;
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	static int segment = 0;
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	// handle display reset
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	if( reset ) {
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		second = 0;
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		segment = 0;
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	}
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	// what needs to be drawn?
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	bool draw_tick = !segment && second % 5 == 0;
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	bool draw_second = !segment && second == time_seconds;
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	bool draw_minute = !segment && second == time_minutes;
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	bool draw_hour = !segment && second == time_hours;
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	// set the LEDs
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	ledOn( 9, true );
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	ledOn( 8, draw_tick || draw_minute );
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	for( int a = 6; a <= 7; a++ )
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		ledOn( a, draw_minute || draw_second );
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	for( int a = 0; a <= 5; a++ )
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		ledOn( a, draw_minute || draw_second || draw_hour );
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	// inc position
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	if( ++segment >= NUM_SECOND_SEGMENTS ) {
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		segment = 0;
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		second++;
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	}
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}
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// draw a display segment
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void drawNextSegment( bool reset )
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{
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	static int draw_mode = 0;
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 	// handle mode switch requests
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	if( reset && inc_draw_mode ) {
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		inc_draw_mode = false;
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		draw_mode++;
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		if( draw_mode >= 2 )
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			draw_mode = 0;
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	}
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	// draw the segment
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	switch( draw_mode ) {
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	case 0: drawNextSegment_test( reset ); break;
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	case 1: drawNextSegment_time( reset ); break;
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	}
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}
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// calculate time constants when a new pulse has occurred
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void calculateSegmentTimes()
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{
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	// check for overflows, and only recalculate times if there isn't
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	// one (if there is, we'll just go with the last pulse's times)
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	if( new_pulse_at > last_pulse_at )
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	{
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		// new segment stepping times
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		unsigned long delta = new_pulse_at - last_pulse_at;
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		segment_step = delta / NUM_SEGMENTS;
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		segment_step_sub = 0;
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		segment_step_sub_step = delta % NUM_SEGMENTS;
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	}
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	// now we have dealt with this pulse, save the pulse time and
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	// clear new_pulse_at, ready for the next pulse
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	last_pulse_at = new_pulse_at;
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	new_pulse_at = 0;
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}
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// wait until it is time to draw the next segment or a new pulse has
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// occurred
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void waitTillNextSegment( bool reset )
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{
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	static unsigned long end_time = 0;
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	// handle reset
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	if( reset )
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		end_time = last_pulse_at;
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	// work out the time that this segment should be displayed until
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	end_time += segment_step;
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	segment_step_sub += segment_step_sub_step;
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	if( segment_step_sub >= NUM_SEGMENTS ) {
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		segment_step_sub -= NUM_SEGMENTS;
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		end_time++;
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	}
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	// wait
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	while( micros() < end_time && !new_pulse_at );
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}
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// ISR to handle the pulses from the fan's tachiometer
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void fanPulseHandler()
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{
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	// the fan actually sends two pulses per revolution. These pulses
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	// may not be exactly evenly distributed around the rotation, so
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	// we can't recalculate times on every pulse. Instead, we ignore
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	// every other pulse so timings are based on a complete rotation.
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	static bool ignore = true;
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	ignore = !ignore;
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	if( !ignore )
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	{
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		// set a new pulse time
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		new_pulse_at = micros();
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	}
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}
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// main setup
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void setup()
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{
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	// set up an interrupt handler on pin 2 to nitice fan pulses
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	attachInterrupt( 0, fanPulseHandler, RISING );
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	digitalWrite( 2, HIGH );
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	// set up output pins (4 to 13) for the led array
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	for( int a = 4; a < 14; a++ )
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		pinMode( a, OUTPUT );
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	// set up mode-switch button on pin 3
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	pinMode( 3, INPUT );
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	digitalWrite( 3, HIGH );
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	// get the time from the real-time clock
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	int rtc_data[ 7 ];
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	RTC.get( rtc_data, true );
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	time_hours = rtc_data[ DS1307_HR ];
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	time_minutes = rtc_data[ DS1307_MIN ];
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	time_seconds = rtc_data[ DS1307_SEC ];
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	// serial comms
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	Serial.begin( 9600 );
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}
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// main loop
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void loop()
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{
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	// if there has been a new pulse, we'll be resetting the display
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	bool reset = new_pulse_at? true : false;
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	// only do this stuff at the start of a display cycle, to ensure
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	// that no state changes mid-display
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	if( reset )
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	{
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		// check buttons
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		checkButtons();
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		// keep track of time
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		trackTime();
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	}
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	// draw this segment
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	drawNextSegment( reset );
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	// do we need to recalculate segment times?
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	if( reset )
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		calculateSegmentTimes();
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	// wait till it's time to draw the next segment
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	waitTillNextSegment( reset );
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}