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1 | /* $Id: ledpwm.c,v 1.6 2010/08/08 18:09:40 simimeie Exp $ |
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2 | * Functions for led brightness control via PWM (pulse width modulation). |
3 | */ |
4 | |
5 | #include <avr/io.h> |
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6 | #include <avr/interrupt.h> |
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7 | #include "ledpwm.h" |
8 | |
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9 | /* |
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10 | * Our hardware connections on the first prototype are as follows: |
11 | * Red -> PD6 (OC0A) |
12 | * Green -> PD5 (OC0B) |
13 | * Blue -> PD3 (OC2B) CHANGED umgeloetet durch Julian jetzt PD7 |
14 | * In the next hardware revision this will be: |
15 | * Red -> PC3 |
16 | * Green -> PC2 |
17 | * Blue -> PC1 |
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18 | */ |
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19 | |
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20 | #define LEDPORT PORTD |
21 | #define LEDDDR DDRD |
22 | #define LEDPINR 6 |
23 | #define LEDPING 5 |
24 | #define LEDPINB 7 |
25 | |
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26 | uint8_t ledpwm_re = 0xff, ledpwm_gr = 0xff, ledpwm_bl = 0xff; |
27 | uint8_t ledpwm_bri = 128; |
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28 | /* Internal */ |
29 | volatile uint16_t ledpwm_val[3] = { 0x8000, 0x8000, 0x8000 }; |
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30 | typedef struct { |
31 | uint16_t atcntval; /* at this counter value */ |
32 | uint8_t orval; /* or this value onto the output */ |
33 | } ledpwm_microprog; |
34 | ledpwm_microprog ledpwm_mprogs[2][10]; |
35 | volatile uint8_t ledpwm_activemprog = 0; |
36 | volatile ledpwm_microprog * ledpwm_amprogptr = &ledpwm_mprogs[0][0]; |
37 | |
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38 | |
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39 | /* To do a 16-bit write, the high byte must be written before the low byte. |
40 | * For a 16-bit read, the low byte must be read before the high byte */ |
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41 | |
42 | static inline uint16_t getnextminimum(uint16_t curmin) { |
43 | uint16_t res = 0xffff; |
44 | uint8_t i; uint8_t found = 0; |
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45 | for (i = 0; i < 3; i++) { |
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46 | if ((ledpwm_val[i] > curmin) && (ledpwm_val[i] <= res)) { |
47 | res = ledpwm_val[i]; |
48 | found = 1; |
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49 | } |
50 | } |
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51 | if (found) { |
52 | return res; |
53 | } else { |
54 | return 0; /* We already had the maximum, no higher values there (EOL) */ |
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55 | } |
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56 | } |
57 | |
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58 | static void ledpwm_recalculateprogram(void) { |
59 | uint8_t nextprog = !ledpwm_activemprog; |
60 | uint8_t i = 0; |
61 | uint16_t nextminimum = 0; |
62 | uint8_t orval; |
63 | |
64 | do { |
65 | orval = 0; |
66 | if (ledpwm_val[LEDPWM_REDLED] > nextminimum) { |
67 | orval |= _BV(LEDPINR); |
68 | } |
69 | if (ledpwm_val[LEDPWM_GREENLED] > nextminimum) { |
70 | orval |= _BV(LEDPING); |
71 | } |
72 | if (ledpwm_val[LEDPWM_BLUELED] > nextminimum) { |
73 | orval |= _BV(LEDPINB); |
74 | } |
75 | ledpwm_mprogs[nextprog][i].atcntval = nextminimum; |
76 | ledpwm_mprogs[nextprog][i].orval = orval; |
77 | /* now calculate nextminimum */ |
78 | nextminimum = getnextminimum(nextminimum); |
79 | i++; |
80 | } while (nextminimum > 0); |
81 | while (i < 10) { /* Fill the rest with dummys that cause no harm */ |
82 | ledpwm_mprogs[nextprog][i].atcntval = 0; |
83 | ledpwm_mprogs[nextprog][i].orval = 0; |
84 | i++; |
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85 | } |
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86 | /* activate the freshly calculated microprogram */ |
87 | ledpwm_activemprog = nextprog; |
88 | return; |
89 | } |
90 | |
91 | static inline void programnextpwmstep(void) { |
92 | uint16_t curcnt; |
93 | curcnt = TCNT1L; |
94 | curcnt |= (uint16_t)TCNT1H << 8; |
95 | while (((curcnt + 40) > ledpwm_amprogptr->atcntval) && (ledpwm_amprogptr->atcntval > 0)) { |
96 | /* Something to do in the next few CPU cycles, so wait for it! */ |
97 | if (curcnt >= ledpwm_amprogptr->atcntval) { /* Execute! */ |
98 | LEDPORT = (LEDPORT & (uint8_t)~(_BV(LEDPINR) | _BV(LEDPING) | _BV(LEDPINB))) | ledpwm_amprogptr->orval; |
99 | ledpwm_amprogptr++; |
100 | } |
101 | curcnt = TCNT1L; |
102 | curcnt |= (uint16_t)TCNT1H << 8; |
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103 | } |
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104 | /* Now program the overflow interrupt */ |
105 | if (ledpwm_amprogptr->atcntval > 0) { |
106 | uint16_t nextval = ledpwm_amprogptr->atcntval; |
107 | OCR1AH = nextval >> 8; |
108 | OCR1AL = nextval & 0xff; |
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109 | } |
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110 | } |
111 | |
112 | /* This gets called from timers.c which holds the 'main' (interrupt) |
113 | * handler for the timer1 overflow. */ |
114 | void ledpwm_TIMER1OVF_hook(void) { |
115 | /* (Re-)Start microprogram */ |
116 | ledpwm_amprogptr = &ledpwm_mprogs[ledpwm_activemprog][0]; |
117 | LEDPORT = (LEDPORT & (uint8_t)~(_BV(LEDPINR) | _BV(LEDPING) | _BV(LEDPINB))) | ledpwm_amprogptr->orval; |
118 | ledpwm_amprogptr++; |
119 | programnextpwmstep(); |
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120 | } |
121 | |
122 | /* Called on compare match */ |
123 | ISR(TIMER1_COMPA_vect) |
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124 | { |
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125 | LEDPORT = (LEDPORT & (uint8_t)~(_BV(LEDPINR) | _BV(LEDPING) | _BV(LEDPINB))) | ledpwm_amprogptr->orval; |
126 | ledpwm_amprogptr++; |
127 | programnextpwmstep(); |
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128 | } |
129 | |
130 | void ledpwm_init(void) { |
131 | /* Set our Port Pins to output */ |
132 | LEDDDR |= _BV(LEDPINR) | _BV(LEDPING) | _BV(LEDPINB); |
133 | /* DO NOT initialize TIMER1 frequency and overflow interrupt. |
134 | * timers.c already does that. */ |
135 | /* Enable TIMER1 output compare interrupt A */ |
136 | TIMSK1 |= _BV(OCIE1A); |
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137 | ledpwm_recalculateprogram(); |
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138 | } |
139 | |
140 | void ledpwm_setled(uint8_t led, uint16_t val) { |
141 | if (led > 2) { return; /* ignore invalid values */ } |
142 | ledpwm_val[led] = val; |
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143 | ledpwm_recalculateprogram(); |
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144 | } |
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145 | |
146 | void ledpwm_set(uint8_t red, uint8_t green, uint8_t blue, uint8_t br) { |
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147 | ledpwm_val[LEDPWM_REDLED] = red * br; |
148 | ledpwm_val[LEDPWM_GREENLED] = green * br; |
149 | ledpwm_val[LEDPWM_BLUELED] = blue * br; |
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150 | ledpwm_recalculateprogram(); |
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151 | } |