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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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/* -*- mode: c++; compile-command: "BOARD=pro5v make"; -*- */
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* Copyright (C) 2011 Tim Marston <tim@ed.am> and Dan Marston.
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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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* 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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* 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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* 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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* 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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* 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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* 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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* pressing the button cycles between variations of the current
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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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// when non-zero, the time (in microseconds) of a new fan pulse that has just
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// occurred, which means that segment drawing needs to be restarted
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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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******************************************************************************/
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#include "mode_switcher.h"
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//_____________________________________________________________________________
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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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static unsigned long new_pulse_at = 0;
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// interrupt handler to count the number of fan pulses
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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 Button button( 3 );
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//_____________________________________________________________________________
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// check for button presses
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int event = button.update();
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inc_draw_mode = true;
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// turn an led on/off
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void ledOn( int num, bool on )
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if( num < 0 || num > 9 ) return;
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// convert to pin no.
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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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// draw a display segment
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void drawNextSegment( bool reset )
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static ModeSwitcher mode_switcher;
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static bool init = false;
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mode_switcher.activate();
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// keep track of segment
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static int segment = ( NUM_SEGMENTS - CLOCK_SHIFT ) % NUM_SEGMENTS;
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if( reset ) segment = ( NUM_SEGMENTS - CLOCK_SHIFT ) % NUM_SEGMENTS;
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static int segment = NUM_SEGMENTS - 1 - CLOCK_SHIFT;
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if( reset ) segment = NUM_SEGMENTS - 1 - CLOCK_SHIFT;
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Drawer &drawer = mode_switcher.get_drawer();
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if( reset ) drawer.draw_reset();
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drawer.draw( segment );
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if( ++segment >= NUM_SEGMENTS ) segment = 0;
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if( --segment < 0 ) segment = NUM_SEGMENTS - 1;
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// calculate time constants when a new pulse has occurred
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void calculateSegmentTimes()
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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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// 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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// 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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// wait until it is time to draw the next segment or a new pulse has
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void waitTillNextSegment( bool reset )
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static unsigned long end_time = 0;
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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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while( micros() < end_time && !new_pulse_at );
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// ISR to handle the pulses from the fan's tachiometer
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void fanPulseHandler()
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// ignore every other pulse
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static bool ignore = true;
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// set a new pulse time
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new_pulse_at = micros();
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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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// set a new pulse time
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new_pulse_at = micros();
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// wait until it is time to draw the next segment or a new pulse has occurred
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void endOfSegmentDelay()
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while( micros() < next_segment_at && !new_pulse_at );
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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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digitalWrite( 3, HIGH );
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button.add_event_at( 5, 1 );
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button.add_event_at( 1000, 2 );
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button.add_event_at( 4000, 3 );
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Serial.begin( 9600 );
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unsigned long loop_start_time = micros();
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// wait till it's time to draw the next segment
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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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// keep track of time
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Time &time = Time::get_instance();
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drawNextSegment( reset );
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// do we need to recalculate segment times?
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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 );
added
removed
src/propeller-clock.ino
