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| Rev | Author | Line No. | Line |
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| 361 | andfri | 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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| 8 | * @date 2006-11-19 |
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| 9 | */ |
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| 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 <config.h> |
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| 19 | #include <drivers/timer/timebase.h> |
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| 20 | |||
| 21 | |||
| 22 | /*----------------------------------------------------------------------------- |
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| 23 | * Globals |
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| 24 | *---------------------------------------------------------------------------*/ |
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| 25 | volatile uint32_t gMilliSecTick; |
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| 26 | |||
| 27 | |||
| 28 | /*----------------------------------------------------------------------------- |
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| 29 | * Interrupt Service Routines |
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| 30 | *---------------------------------------------------------------------------*/ |
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| 31 | #if defined(TIMER2) |
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| 32 | ISR(SIG_OVERFLOW2) { |
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| 33 | TCNT2 = TIMEBASE_RELOAD; |
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| 34 | gMilliSecTick++; |
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| 35 | } |
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| 36 | #else |
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| 37 | ISR(SIG_OVERFLOW0) { |
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| 38 | TCNT0 = TIMEBASE_RELOAD; |
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| 39 | gMilliSecTick++; |
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| 40 | } |
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| 41 | #endif |
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| 42 | |||
| 43 | |||
| 44 | /*----------------------------------------------------------------------------- |
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| 45 | * Public Functions |
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| 46 | *---------------------------------------------------------------------------*/ |
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| 47 | |||
| 48 | /** |
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| 49 | * Initializes the timebase. The hardware timer interrupt source will be |
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| 50 | * enabled, but global interrupts need to be enabled by the application. |
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| 51 | */ |
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| 52 | void Timebase_Init() { |
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| 53 | #if defined(TIMER2) |
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| 54 | #if defined(__AVR_ATmega8__) |
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| 55 | #if TIMEBASE_PRESCALE == 64 |
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| 56 | TCCR2 = (1<<CS22); // prescaler: 64 |
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| 57 | #elif TIMEBASE_PRESCALE == 256 |
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| 58 | TCCR2 = (1<<CS22) | (1<<CS21); // prescaler: 256 |
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| 59 | #endif |
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| 60 | TCNT2 = TIMEBASE_RELOAD; // set initial reload-value |
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| 61 | TIFR |= (1<<TOV2); // clear overflow int. |
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| 62 | TIMSK |= (1<<TOIE2); // enable overflow-interrupt |
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| 63 | #endif |
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| 64 | |||
| 372 | arune | 65 | #if defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__) |
| 361 | andfri | 66 | #if TIMEBASE_PRESCALE == 64 |
| 67 | TCCR2B = (1<<CS22); // prescaler: 64 |
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| 68 | #elif TIMEBASE_PRESCALE == 256 |
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| 69 | TCCR2B = (1<<CS22)|(1<<CS21); // prescaler: 256 |
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| 70 | #endif |
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| 71 | TCNT2 = TIMEBASE_RELOAD; // set initial reload-value |
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| 72 | TIFR2 |= (1<<TOV2); // clear overflow int. |
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| 73 | TIMSK2 |= (1<<TOIE2); // enable overflow-interrupt |
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| 74 | #endif |
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| 75 | #else /* Use timer0 */ |
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| 76 | #if defined(__AVR_ATmega8__) |
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| 77 | #if TIMEBASE_PRESCALE == 64 |
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| 78 | TCCR0 = (1<<CS01) | (1<<CS00); // prescaler: 64 |
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| 79 | #elif TIMEBASE_PRESCALE == 256 |
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| 80 | TCCR0 = (1<<CS02); // prescaler: 256 |
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| 81 | #endif |
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| 82 | TCNT0 = TIMEBASE_RELOAD; // set initial reload-value |
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| 83 | TIFR |= (1<<TOV0); // clear overflow int. |
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| 84 | TIMSK |= (1<<TOIE0); // enable overflow-interrupt |
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| 85 | #endif |
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| 86 | |||
| 372 | arune | 87 | #if defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__) |
| 361 | andfri | 88 | #if TIMEBASE_PRESCALE == 64 |
| 89 | TCCR0B = (1<<CS01) | (1<<CS00); // prescaler: 64 |
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| 90 | #elif TIMEBASE_PRESCALE == 256 |
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| 91 | TCCR0B = (1<<CS02); // prescaler: 256 |
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| 92 | #endif |
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| 93 | TCNT0 = TIMEBASE_RELOAD; // set initial reload-value |
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| 94 | TIFR0 |= (1<<TOV0); // clear overflow int. |
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| 95 | TIMSK0 |= (1<<TOIE0); // enable overflow-interrupt |
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| 96 | #endif |
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| 97 | #endif |
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| 98 | } |
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| 99 | |||
| 100 | |||
| 101 | /** |
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| 102 | * Reads the current time. |
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| 103 | * |
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| 104 | * @return |
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| 105 | * The current time in milliseconds (32bit value). |
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| 106 | */ |
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| 107 | uint32_t Timebase_CurrentTime(void) { |
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| 108 | uint8_t sreg; |
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| 362 | andfri | 109 | uint32_t res; |
| 361 | andfri | 110 | sreg=SREG; |
| 111 | cli(); |
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| 112 | res = gMilliSecTick; |
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| 113 | SREG=sreg; |
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| 114 | return res; |
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| 115 | } |
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| 116 | |||
| 117 | |||
| 118 | /** |
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| 119 | * Checks how much time has passed since a given timestamp. |
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| 120 | * |
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| 121 | * @param t0 |
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| 122 | * The timestamp. |
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| 123 | * @return |
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| 124 | * Number of milliseconds that have passed since t0. |
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| 125 | */ |
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| 126 | uint32_t Timebase_PassedTimeMillis(uint32_t t0) { |
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| 127 | uint8_t sreg; |
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| 362 | andfri | 128 | uint32_t res; |
| 361 | andfri | 129 | sreg=SREG; |
| 130 | cli(); |
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| 362 | andfri | 131 | res = (uint32_t)(gMilliSecTick-t0); |
| 361 | andfri | 132 | SREG=sreg; |
| 133 | return res; |
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| 134 | } |