4
* Copyright (C) 2011 Tim Marston <edam@waxworlds.org>
6
* This file is part of propeller-clock (hereafter referred to as "this
7
* program"). See http://ed.am/software/arduino/propeller-clock for more
10
* This program is free software: you can redistribute it and/or modify
11
* it under the terms of the GNU Lesser General Public License as published
12
* by the Free Software Foundation, either version 3 of the License, or
13
* (at your option) any later version.
15
* This program is distributed in the hope that it will be useful,
16
* but WITHOUT ANY WARRANTY; without even the implied warranty of
17
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18
* GNU Lesser General Public License for more details.
20
* You should have received a copy of the GNU Lesser General Public License
21
* along with this program. If not, see <http://www.gnu.org/licenses/>.
24
/******************************************************************************
26
For a schematic, see propeller-clock.sch.
30
- a PC fan is wired up to the 12V supply.
32
- the fan's SENSE (tachiometer) pin is connected to pin 2 on the
35
- the pins 4 to 13 on the arduino should directly drive an LED (the
36
LED on pin 4 is in the centre of the clock face and the LED on pin
39
- if a longer hand (and a larger clock face) is desired, pin 4 can
40
be used to indirectly drive (via a MOSFET) multiple LEDs which
41
turn on and off in unison in the centre of the clock.
43
- a button should be attached to pin 3 that grounds it when pressed.
45
Implementation details:
47
- the timing of the drawing of the clock face is recalculated with
48
every rotation of the propeller (for maximum update speed).
50
- pressing the button cycles between display modes
52
- holding down the button for 2 seconds enters "set time" mode. In
53
this mode, the fan must be held still and the LEDs will indicate
54
what number is being entered for each time digit. Pressing the
55
button increments the current digit. Holding it down moves to the
56
next digit (or leaves "set time" mode when there are no more). In
57
order, the digits (with accepted values) are: hours-tens (0 to 2),
58
hours-ones (0 to 9), minutes-tens (0 to 5), minutes-ones (0 to 9).
60
******************************************************************************/
65
//_____________________________________________________________________________
69
// when non-zero, the time (in microseconds) of a new fan pulse that
70
// has just occurred, which means that segment drawing needs to be
72
static unsigned long new_pulse_at = 0;
74
// the time (in microseconds) when the last fan pulse occurred
75
static unsigned long last_pulse_at = 0;
77
// duration (in microseconds) that a segment should be displayed
78
static unsigned long segment_step = 0;
80
// remainder after divisor and a tally of the remainders for each segment
81
static unsigned long segment_step_sub_step = 0;
82
static unsigned long segment_step_sub = 0;
84
// flag to indicate that the drawing mode should be cycled to the next one
85
static bool inc_draw_mode = false;
87
// a bounce-managed button
88
static Bounce button( 3, 5 );
91
static int time_hours = 0;
92
static int time_minutes = 0;
93
static int time_seconds = 0;
95
// number of segments in a full display (rotation) is 60 (one per
96
// second) times the desired number of sub-divisions of a second
97
#define NUM_SECOND_SEGMENTS 5
98
#define NUM_SEGMENTS ( 60 * NUM_SECOND_SEGMENTS )
100
//_____________________________________________________________________________
104
// check for button presses
110
// notice button presses
111
if( button.risingEdge() )
112
inc_draw_mode = true;
116
// keep track of time
119
// previous time and any carried-over milliseconds
120
static unsigned long last_time = millis();
121
static unsigned long carry = 0;
123
// how many milliseonds have elapsed since we last checked?
124
unsigned long next_time = millis();
125
unsigned long delta = next_time - last_time + carry;
127
// update the previous time and carried-over milliseconds
128
last_time = next_time;
129
carry = delta % 1000;
131
// add the seconds that have passed to the time
132
time_seconds += delta / 1000;
133
while( time_seconds >= 60 ) {
136
if( time_minutes >= 60 ) {
139
if( time_hours >= 24 )
146
// draw a segment for the test display
147
void drawNextSegment_test( bool reset )
149
// keep track of segment
150
static unsigned int segment = 0;
151
if( reset ) segment = 0;
154
// turn on inside and outside LEDs
155
digitalWrite( 4, HIGH );
156
digitalWrite( 13, HIGH );
158
// display segment number in binary across in the inside LEDs,
159
// with the LED on pin 12 showing the least-significant bit
160
for( int a = 0; a < 8; a++ )
161
digitalWrite( 12 - a, ( ( segment >> a ) & 1 )? HIGH : LOW );
165
// draw a segment for the time display
166
void drawNextSegment_time( bool reset )
168
static unsigned int second = 0;
169
static unsigned int segment = 0;
171
// handle display reset
177
// what needs to be drawn?
178
bool draw_tick = !segment && second % 5 == 0;
179
bool draw_second = !segment && second == time_seconds;
180
bool draw_minute = !segment && second == time_minute;
181
bool draw_hour = !segment && second == time_hour;
184
digitalWrite( 13, HIGH );
185
digitalWrite( 12, draw_tick || draw_minute );
186
for( int a = 10; a <= 11; a++ )
187
digitalWrite( a, draw_minute || draw_second );
188
for( int a = 4; a <= 9; a++ )
189
digitalWrite( 10, draw_minute | draw_second || draw_hour );
192
if( ++segment >= NUM_SECOND_SEGMENTS ) {
199
// draw a display segment
200
void drawNextSegment( bool reset )
202
static int draw_mode = 0;
204
// handle mode switch requests
205
if( reset && inc_draw_mode ) {
206
inc_draw_mode = false;
213
switch( draw_mode ) {
214
case 0: drawNextSegment_test( reset ); break;
215
case 1: drawNextSegment_time( reset ); break;
220
// calculate time constants when a new pulse has occurred
221
void calculateSegmentTimes()
223
// check for overflows, and only recalculate times if there isn't
224
// one (if there is, we'll just go with the last pulse's times)
225
if( new_pulse_at > last_pulse_at )
227
// new segment stepping times
228
unsigned long delta = new_pulse_at - last_pulse_at;
229
segment_step = delta / NUM_SEGMENTS;
230
segment_step_sub = 0;
231
segment_step_sub_step = delta % NUM_SEGMENTS;
234
// now we have dealt with this pulse, save the pulse time and
235
// clear new_pulse_at, ready for the next pulse
236
last_pulse_at = new_pulse_at;
241
// wait until it is time to draw the next segment or a new pulse has
243
void waitTillNextSegment( bool reset )
245
static unsigned long end_time = 0;
249
end_time = last_pulse_at;
251
// work out the time that this segment should be displayed until
252
end_time += segment_step;
253
segment_step_sub += segment_step_sub_step;
254
if( segment_step_sub >= NUM_SEGMENTS ) {
255
segment_step_sub -= NUM_SEGMENTS;
260
while( micros() < end_time && !new_pulse_at );
264
// ISR to handle the pulses from the fan's tachiometer
265
void fanPulseHandler()
267
// the fan actually sends two pulses per revolution. These pulses
268
// may not be exactly evenly distributed around the rotation, so
269
// we can't recalculate times on every pulse. Instead, we ignore
270
// every other pulse so timings are based on a complete rotation.
271
static bool ignore = true;
275
// set a new pulse time
276
new_pulse_at = micros();
284
// set up an interrupt handler on pin 2 to nitice fan pulses
285
attachInterrupt( 0, fanPulseHandler, RISING );
286
digitalWrite( 2, HIGH );
288
// set up output pins (4 to 13) for the led array
289
for( int a = 4; a < 14; a++ )
290
pinMode( a, OUTPUT );
292
// set up mode-switch button on pin 3
296
Serial.begin( 9600 );
303
// if there has been a new pulse, we'll be resetting the display
304
bool reset = new_pulse_at? true : false;
306
// only do this stuff at the start of a display cycle, to ensure
307
// that no state changes mid-display
313
// keep track of time
318
drawNextSegment( reset );
320
// do we need to recalculate segment times?
322
calculateSegmentTimes();
324
// wait till it's time to draw the next segment
325
waitTillNextSegment( reset );