Details | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 231 | killagreg | 1 | #include <inttypes.h> |
| 2 | #include <avr/io.h> |
||
| 3 | #include <avr/interrupt.h> |
||
| 4 | |||
| 274 | killagreg | 5 | #include "timer0.h" |
| 231 | killagreg | 6 | |
| 7 | volatile uint16_t CountMilliseconds = 0; |
||
| 274 | killagreg | 8 | DateTime_t SystemTime; |
| 9 | |||
| 271 | killagreg | 10 | #ifdef USE_FOLLOWME |
| 11 | volatile uint16_t BeepTime = 0; |
||
| 12 | volatile uint16_t BeepModulation = 0xFFFF; |
||
| 13 | #endif |
||
| 231 | killagreg | 14 | |
| 15 | |||
| 16 | /*****************************************************/ |
||
| 17 | /* Initialize Timer 0 */ |
||
| 18 | /*****************************************************/ |
||
| 19 | // timer 0 is used for the PWM generation to control the offset voltage at the air pressure sensor |
||
| 20 | // Its overflow interrupt routine is used to generate the beep signal and the flight control motor update rate |
||
| 21 | void TIMER0_Init(void) |
||
| 22 | { |
||
| 23 | uint8_t sreg = SREG; |
||
| 24 | |||
| 25 | // disable all interrupts before reconfiguration |
||
| 26 | cli(); |
||
| 27 | |||
| 271 | killagreg | 28 | |
| 29 | // configure speaker port as output |
||
| 30 | |||
| 31 | #ifdef USE_FOLLOWME |
||
| 32 | // Speaker at PC7 |
||
| 33 | DDRC |= (1<<DDC7); |
||
| 34 | PORTC &= ~(1<<PORTC7); |
||
| 35 | #endif |
||
| 36 | |||
| 231 | killagreg | 37 | // Timer/Counter 0 Control Register A |
| 38 | |||
| 39 | // Waveform Generation Mode is Fast PWM (Bits WGM02 = 0, WGM01 = 1, WGM00 = 1) |
||
| 40 | // Clear OC0A on Compare Match, set OC0A at BOTTOM, noninverting PWM (Bits COM0A1 = 1, COM0A0 = 0) |
||
| 41 | // Clear OC0B on Compare Match, set OC0B at BOTTOM, (Bits COM0B1 = 1, COM0B0 = 0) |
||
| 42 | TCCR0A &= ~((1<<COM0A0)|(1<<COM0B0)); |
||
| 43 | TCCR0A |= (1<<COM0A1)|(1<<COM0B1)|(1<<WGM01)|(1<<WGM00); |
||
| 44 | |||
| 45 | // Timer/Counter 0 Control Register B |
||
| 46 | |||
| 47 | // set clock devider for timer 0 to SYSKLOCK/8 = 20MHz / 8 = 2.5MHz |
||
| 48 | // i.e. the timer increments from 0x00 to 0xFF with an update rate of 2.5 MHz |
||
| 49 | // hence the timer overflow interrupt frequency is 2.5 MHz / 256 = 9.765 kHz |
||
| 50 | |||
| 51 | // divider 8 (Bits CS02 = 0, CS01 = 1, CS00 = 0) |
||
| 52 | TCCR0B &= ~((1<<FOC0A)|(1<<FOC0B)|(1<<WGM02)); |
||
| 53 | TCCR0B = (TCCR0B & 0xF8)|(0<<CS02)|(1<<CS01)|(0<<CS00); |
||
| 54 | |||
| 55 | // initialize the Output Compare Register A & B used for PWM generation on port PB3 & PB4 |
||
| 56 | OCR0A = 0; // for PB3 |
||
| 57 | OCR0B = 120; // for PB4 |
||
| 58 | |||
| 59 | // init Timer/Counter 0 Register |
||
| 60 | TCNT0 = 0; |
||
| 61 | |||
| 62 | // Timer/Counter 0 Interrupt Mask Register |
||
| 63 | // enable timer overflow interrupt only |
||
| 64 | TIMSK0 &= ~((1<<OCIE0B)|(1<<OCIE0A)); |
||
| 65 | TIMSK0 |= (1<<TOIE0); |
||
| 66 | |||
| 274 | killagreg | 67 | |
| 68 | SystemTime.Year = 0; |
||
| 69 | SystemTime.Month = 0; |
||
| 70 | SystemTime.Day = 0; |
||
| 71 | SystemTime.Hour = 0; |
||
| 72 | SystemTime.Min = 0; |
||
| 73 | SystemTime.Sec = 0; |
||
| 74 | SystemTime.mSec = 0; |
||
| 75 | SystemTime.Valid = 0; |
||
| 76 | |||
| 77 | CountMilliseconds = 0; |
||
| 78 | |||
| 79 | |||
| 231 | killagreg | 80 | SREG = sreg; |
| 81 | } |
||
| 82 | |||
| 83 | |||
| 84 | |||
| 85 | /*****************************************************/ |
||
| 86 | /* Interrupt Routine of Timer 0 */ |
||
| 87 | /*****************************************************/ |
||
| 88 | ISR(TIMER0_OVF_vect) // 9.765 kHz |
||
| 89 | { |
||
| 90 | static uint8_t cnt = 0; |
||
| 271 | killagreg | 91 | #ifdef USE_FOLLOWME |
| 92 | uint8_t Beeper_On = 0; |
||
| 93 | #endif |
||
| 231 | killagreg | 94 | |
| 95 | if(!cnt--) // every 10th run (9.765kHz/10 = 976Hz) |
||
| 96 | { |
||
| 97 | cnt = 9; |
||
| 98 | CountMilliseconds++; // increment millisecond counter |
||
| 99 | } |
||
| 271 | killagreg | 100 | |
| 101 | #ifdef USE_FOLLOWME |
||
| 102 | // beeper on if duration is not over |
||
| 103 | if(BeepTime) |
||
| 104 | { |
||
| 105 | BeepTime--; // decrement BeepTime |
||
| 106 | if(BeepTime & BeepModulation) Beeper_On = 1; |
||
| 107 | else Beeper_On = 0; |
||
| 108 | } |
||
| 109 | else // beeper off if duration is over |
||
| 110 | { |
||
| 111 | Beeper_On = 0; |
||
| 112 | BeepModulation = 0xFFFF; |
||
| 113 | } |
||
| 114 | |||
| 115 | // if beeper is on |
||
| 116 | if(Beeper_On) |
||
| 117 | { |
||
| 118 | // set speaker port to high |
||
| 119 | PORTC |= (1<<PORTC7); // Speaker at PC7 |
||
| 120 | } |
||
| 121 | else // beeper is off |
||
| 122 | { |
||
| 123 | // set speaker port to low |
||
| 124 | PORTC &= ~(1<<PORTC7);// Speaker at PC7 |
||
| 125 | } |
||
| 126 | #endif |
||
| 231 | killagreg | 127 | } |
| 128 | |||
| 129 | |||
| 130 | // ----------------------------------------------------------------------- |
||
| 131 | uint16_t SetDelay (uint16_t t) |
||
| 132 | { |
||
| 133 | return(CountMilliseconds + t - 1); |
||
| 134 | } |
||
| 135 | |||
| 136 | // ----------------------------------------------------------------------- |
||
| 137 | int8_t CheckDelay(uint16_t t) |
||
| 138 | { |
||
| 139 | return(((t - CountMilliseconds) & 0x8000) >> 8); // check sign bit |
||
| 140 | } |
||
| 141 | |||
| 142 | // ----------------------------------------------------------------------- |
||
| 143 | void Delay_ms(uint16_t w) |
||
| 144 | { |
||
| 145 | unsigned int t_stop; |
||
| 146 | t_stop = SetDelay(w); |
||
| 147 | while (!CheckDelay(t_stop)); |
||
| 148 | } |
||
| 149 |