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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 60 | jimmy | 1 | /** |
| 2 | * Timebase software module. Utilizes timer0 to provide a 32bit timebase with |
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| 3 | * millisecond-granularity to the application. |
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| 4 | * |
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| 5 | * @author Martin Thomas |
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| 6 | * @author Jimmy Myhrman |
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| 7 | * |
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| 127 | jimmy | 8 | * @date 2006-11-19 |
| 60 | jimmy | 9 | */ |
| 10 | |||
| 11 | /*----------------------------------------------------------------------------- |
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| 12 | * Includes |
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| 13 | *---------------------------------------------------------------------------*/ |
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| 14 | #include <inttypes.h> |
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| 15 | #include <avr/io.h> |
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| 16 | #include <avr/interrupt.h> |
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| 17 | |||
| 18 | #include <timebase.h> |
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| 19 | |||
| 20 | |||
| 21 | /*----------------------------------------------------------------------------- |
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| 22 | * Globals |
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| 23 | *---------------------------------------------------------------------------*/ |
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| 24 | volatile uint32_t gMilliSecTick; |
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| 25 | |||
| 26 | |||
| 27 | /*----------------------------------------------------------------------------- |
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| 28 | * Interrupt Service Routines |
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| 29 | *---------------------------------------------------------------------------*/ |
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| 247 | eqlazer | 30 | #if defined(TIMER2) |
| 31 | ISR(SIG_OVERFLOW2) { |
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| 32 | TCNT2 = TIMEBASE_RELOAD; |
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| 33 | gMilliSecTick++; |
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| 34 | } |
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| 35 | #else |
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| 60 | jimmy | 36 | ISR(SIG_OVERFLOW0) { |
| 37 | TCNT0 = TIMEBASE_RELOAD; |
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| 38 | gMilliSecTick++; |
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| 39 | } |
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| 247 | eqlazer | 40 | #endif |
| 60 | jimmy | 41 | |
| 42 | |||
| 43 | /*----------------------------------------------------------------------------- |
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| 44 | * Public Functions |
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| 45 | *---------------------------------------------------------------------------*/ |
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| 149 | jimmy | 46 | |
| 60 | jimmy | 47 | /** |
| 48 | * Initializes the timebase. The hardware timer interrupt source will be |
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| 49 | * enabled, but global interrupts need to be enabled by the application. |
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| 50 | */ |
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| 127 | jimmy | 51 | void Timebase_Init() { |
| 247 | eqlazer | 52 | #if defined(TIMER2) |
| 53 | #if defined(__AVR_ATmega8__) |
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| 54 | #if TIMEBASE_PRESCALE == 64 |
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| 272 | jimmy | 55 | TCCR2 = (1<<CS22); // prescaler: 64 |
| 247 | eqlazer | 56 | #elif TIMEBASE_PRESCALE == 256 |
| 272 | jimmy | 57 | TCCR2 = (1<<CS22) | (1<<CS21); // prescaler: 256 |
| 247 | eqlazer | 58 | #endif |
| 59 | TCNT2 = TIMEBASE_RELOAD; // set initial reload-value |
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| 60 | TIFR |= (1<<TOV2); // clear overflow int. |
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| 61 | TIMSK |= (1<<TOIE2); // enable overflow-interrupt |
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| 62 | #endif |
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| 149 | jimmy | 63 | |
| 381 | eqlazer | 64 | #if defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__) |
| 247 | eqlazer | 65 | #if TIMEBASE_PRESCALE == 64 |
| 255 | eqlazer | 66 | TCCR2B = (1<<CS22); // prescaler: 64 |
| 247 | eqlazer | 67 | #elif TIMEBASE_PRESCALE == 256 |
| 255 | eqlazer | 68 | TCCR2B = (1<<CS22)|(1<<CS21); // prescaler: 256 |
| 247 | eqlazer | 69 | #endif |
| 70 | TCNT2 = TIMEBASE_RELOAD; // set initial reload-value |
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| 71 | TIFR2 |= (1<<TOV2); // clear overflow int. |
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| 72 | TIMSK2 |= (1<<TOIE2); // enable overflow-interrupt |
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| 73 | #endif |
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| 74 | #else /* Use timer0 */ |
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| 149 | jimmy | 75 | #if defined(__AVR_ATmega8__) |
| 224 | arune | 76 | #if TIMEBASE_PRESCALE == 64 |
| 219 | arune | 77 | TCCR0 = (1<<CS01) | (1<<CS00); // prescaler: 64 |
| 224 | arune | 78 | #elif TIMEBASE_PRESCALE == 256 |
| 219 | arune | 79 | TCCR0 = (1<<CS02); // prescaler: 256 |
| 80 | #endif |
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| 60 | jimmy | 81 | TCNT0 = TIMEBASE_RELOAD; // set initial reload-value |
| 82 | TIFR |= (1<<TOV0); // clear overflow int. |
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| 83 | TIMSK |= (1<<TOIE0); // enable overflow-interrupt |
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| 149 | jimmy | 84 | #endif |
| 85 | |||
| 381 | eqlazer | 86 | #if defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__) |
| 219 | arune | 87 | #if TIMEBASE_PRESCALE == 64 |
| 88 | TCCR0B = (1<<CS01) | (1<<CS00); // prescaler: 64 |
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| 89 | #elif TIMEBASE_PRESCALE == 256 |
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| 90 | TCCR0B = (1<<CS02); // prescaler: 256 |
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| 91 | #endif |
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| 149 | jimmy | 92 | TCNT0 = TIMEBASE_RELOAD; // set initial reload-value |
| 93 | TIFR0 |= (1<<TOV0); // clear overflow int. |
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| 94 | TIMSK0 |= (1<<TOIE0); // enable overflow-interrupt |
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| 247 | eqlazer | 95 | #endif |
| 96 | #endif |
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| 60 | jimmy | 97 | } |
| 98 | |||
| 149 | jimmy | 99 | |
| 60 | jimmy | 100 | /** |
| 101 | * Reads the current time. |
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| 102 | * |
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| 103 | * @return |
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| 104 | * The current time in milliseconds (32bit value). |
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| 105 | */ |
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| 127 | jimmy | 106 | uint32_t Timebase_CurrentTime(void) { |
| 60 | jimmy | 107 | uint8_t sreg; |
| 108 | uint16_t res; |
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| 109 | sreg=SREG; |
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| 110 | cli(); |
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| 111 | res = gMilliSecTick; |
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| 112 | SREG=sreg; |
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| 113 | return res; |
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| 114 | } |
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| 115 | |||
| 149 | jimmy | 116 | |
| 60 | jimmy | 117 | /** |
| 118 | * Checks how much time has passed since a given timestamp. |
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| 119 | * |
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| 120 | * @param t0 |
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| 121 | * The timestamp. |
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| 122 | * @return |
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| 123 | * Number of milliseconds that have passed since t0. |
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| 124 | */ |
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| 127 | jimmy | 125 | uint32_t Timebase_PassedTimeMillis(uint32_t t0) { |
| 60 | jimmy | 126 | uint8_t sreg; |
| 127 | uint16_t res; |
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| 128 | sreg=SREG; |
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| 129 | cli(); |
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| 130 | res = (uint16_t)(gMilliSecTick-t0); |
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| 131 | SREG=sreg; |
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| 132 | return res; |
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| 133 | } |