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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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| 30 | ISR(SIG_OVERFLOW0) { |
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| 31 | TCNT0 = TIMEBASE_RELOAD; |
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| 32 | gMilliSecTick++; |
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| 33 | } |
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| 34 | |||
| 35 | |||
| 36 | /*----------------------------------------------------------------------------- |
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| 37 | * Public Functions |
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| 38 | *---------------------------------------------------------------------------*/ |
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| 149 | jimmy | 39 | |
| 60 | jimmy | 40 | /** |
| 41 | * Initializes the timebase. The hardware timer interrupt source will be |
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| 42 | * enabled, but global interrupts need to be enabled by the application. |
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| 43 | */ |
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| 127 | jimmy | 44 | void Timebase_Init() { |
| 149 | jimmy | 45 | |
| 46 | #if defined(__AVR_ATmega8__) |
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| 60 | jimmy | 47 | TCCR0 = (1<<CS01) | (1<<CS00); // prescaler: 64 |
| 48 | TCNT0 = TIMEBASE_RELOAD; // set initial reload-value |
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| 49 | TIFR |= (1<<TOV0); // clear overflow int. |
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| 50 | TIMSK |= (1<<TOIE0); // enable overflow-interrupt |
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| 149 | jimmy | 51 | #endif |
| 52 | |||
| 53 | #if defined(__AVR_ATmega88__) |
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| 54 | TCCR0A = (1<<CS01) | (1<<CS00); // prescaler: 64 |
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| 55 | TCNT0 = TIMEBASE_RELOAD; // set initial reload-value |
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| 56 | TIFR0 |= (1<<TOV0); // clear overflow int. |
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| 57 | TIMSK0 |= (1<<TOIE0); // enable overflow-interrupt |
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| 58 | #endif |
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| 60 | jimmy | 59 | } |
| 60 | |||
| 149 | jimmy | 61 | |
| 60 | jimmy | 62 | /** |
| 63 | * Reads the current time. |
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| 64 | * |
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| 65 | * @return |
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| 66 | * The current time in milliseconds (32bit value). |
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| 67 | */ |
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| 127 | jimmy | 68 | uint32_t Timebase_CurrentTime(void) { |
| 60 | jimmy | 69 | uint8_t sreg; |
| 70 | uint16_t res; |
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| 71 | sreg=SREG; |
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| 72 | cli(); |
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| 73 | res = gMilliSecTick; |
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| 74 | SREG=sreg; |
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| 75 | return res; |
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| 76 | } |
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| 77 | |||
| 149 | jimmy | 78 | |
| 60 | jimmy | 79 | /** |
| 80 | * Checks how much time has passed since a given timestamp. |
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| 81 | * |
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| 82 | * @param t0 |
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| 83 | * The timestamp. |
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| 84 | * @return |
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| 85 | * Number of milliseconds that have passed since t0. |
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| 86 | */ |
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| 127 | jimmy | 87 | uint32_t Timebase_PassedTimeMillis(uint32_t t0) { |
| 60 | jimmy | 88 | uint8_t sreg; |
| 89 | uint16_t res; |
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| 90 | sreg=SREG; |
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| 91 | cli(); |
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| 92 | res = (uint16_t)(gMilliSecTick-t0); |
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| 93 | SREG=sreg; |
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| 94 | return res; |
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| 95 | } |