blob: 736671cafeacb821ca6e1e0180ea27e2eb3d622f (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
|
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <avr/wdt.h>
#include <util/delay.h>
#include <stdlib.h>
volatile uint8_t disp[16];
int main (void)
{
wdt_disable();
DDRB = 0xff;
DDRD = 0xff;
PORTB = 0;
PORTD = 0;
TCCR0A = _BV(CS00); // no prescaler (/8 without software prescaler is okay too)
TIMSK0 = _BV(TOIE0); // interrupt on overflow
// smile!
disp[0] = 0x08;
disp[1] = 0x04;
disp[2] = 0x62;
disp[3] = 0x02;
disp[4] = 0x02;
disp[5] = 0x62;
disp[6] = 0x04;
disp[7] = 0x08;
disp[8] = 0x28;
disp[9] = 0x44;
disp[10] = 0x22;
disp[11] = 0x02;
disp[12] = 0x02;
disp[13] = 0x22;
disp[14] = 0x44;
disp[15] = 0x28;
sei();
while (1) {
sleep_enable();
}
return 0;
}
ISR(TIMER0_OVF_vect)
{
static uint8_t active_col = 0;
static uint16_t scroll = 0;
static uint8_t disp_offset = 0;
uint8_t buffer_col;
if (++scroll == 1024) {
scroll = 0;
if (++disp_offset == sizeof(disp)) {
disp_offset = 0;
}
}
buffer_col = (disp_offset + active_col) % sizeof(disp);
/*
* To avoid flickering, do not put any code (or expensive index
* calculations) between the following three lines.
*/
PORTB = 0;
PORTD = ~disp[buffer_col];
PORTB = _BV(active_col);
if (++active_col == 8)
active_col = 0;
}
|
