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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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* 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 "analogue_clock.h"
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#include "digital_clock.h"
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#include "test_pattern.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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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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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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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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// 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_SEGMENTS ( 60 * 5 )
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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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static Button _button( 3 );
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static int _major_mode = 0;
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static int _minor_mode = 0;
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#define MAIN_MODE_IDX 0
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#define ANALOGUE_CLOCK_IDX 0
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#define DIGITAL_CLOCK_IDX 1
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#define TEST_PATTERN_IDX 2
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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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// 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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// activate the current minor mode
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void activate_minor_mode()
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switch( _minor_mode ) {
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case DIGITAL_CLOCK_IDX: digital_clock_activate(); break;
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// perform button events
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void do_button_events()
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// loop through pending events
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while( int event = _button.get_event() )
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// set a new pulse time
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new_pulse_at = micros();
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switch( _major_mode ) {
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switch( _minor_mode ) {
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case ANALOGUE_CLOCK_IDX: analogue_clock_press(); break;
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case DIGITAL_CLOCK_IDX: digital_clock_press(); break;
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switch( _major_mode ) {
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if( ++_minor_mode >= 3 )
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switch( _minor_mode ) {
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case DIGITAL_CLOCK_IDX: digital_clock_activate(); break;
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// looooong press (change major mode)
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if( ++_major_mode > 0 )
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switch( _major_mode ) {
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case MAIN_MODE_IDX: _minor_mode = 0; break;
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activate_minor_mode();
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// draw a particular segment
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void drawNextSegment( bool reset )
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// draw a display segment
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void draw_next_segment( bool reset )
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static unsigned int segment = 0;
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if( reset ) segment = 0;
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for( int a = 0; a < 10; a++ )
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digitalWrite( a + 4, ( ( segment >> a ) & 1 )? HIGH : LOW );
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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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switch( _major_mode ) {
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switch( _minor_mode ) {
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case ANALOGUE_CLOCK_IDX: analogue_clock_draw( segment ); break;
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case DIGITAL_CLOCK_IDX: digital_clock_draw( segment ); break;
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case TEST_PATTERN_IDX: test_pattern_draw( segment ); break;
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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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void calculate_segment_times()
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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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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_step = delta % NUM_SEGMENTS;
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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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_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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void wait_till_end_of_segment( 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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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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semgment_step_sub += semgment_step_sub_step;
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if( semgment_step_sub >= NUM_SEGMENTS ) {
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semgment_step_sub -= NUM_SEGMENTS;
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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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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 fan_pulse_handler()
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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();