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Rev | Author | Line No. | Line |
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231 | killagreg | 1 | #include <inttypes.h> |
2 | #include <avr/io.h> |
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3 | #include <avr/interrupt.h> |
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4 | |||
274 | killagreg | 5 | #include "timer0.h" |
231 | killagreg | 6 | |
7 | volatile uint16_t CountMilliseconds = 0; |
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274 | killagreg | 8 | DateTime_t SystemTime; |
9 | |||
271 | killagreg | 10 | volatile uint16_t BeepTime = 0; |
11 | volatile uint16_t BeepModulation = 0xFFFF; |
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231 | killagreg | 12 | |
13 | /*****************************************************/ |
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14 | /* Initialize Timer 0 */ |
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15 | /*****************************************************/ |
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16 | // timer 0 is used for the PWM generation to control the offset voltage at the air pressure sensor |
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17 | // Its overflow interrupt routine is used to generate the beep signal and the flight control motor update rate |
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18 | void TIMER0_Init(void) |
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19 | { |
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20 | uint8_t sreg = SREG; |
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21 | |||
22 | // disable all interrupts before reconfiguration |
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23 | cli(); |
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24 | |||
271 | killagreg | 25 | |
26 | // configure speaker port as output |
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27 | |||
28 | #ifdef USE_FOLLOWME |
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29 | // Speaker at PC7 |
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30 | DDRC |= (1<<DDC7); |
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31 | PORTC &= ~(1<<PORTC7); |
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32 | #endif |
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33 | |||
231 | killagreg | 34 | // Timer/Counter 0 Control Register A |
35 | |||
296 | killagreg | 36 | // Waveform Generation None (Bits WGM02 = 0, WGM01 = 0, WGM00 = 0) |
37 | TCCR0A &= ~((1<<COM0A0)|(1<<COM0B0)|(1<<COM0A1)|(1<<COM0B1)|(1<<WGM01)|(1<<WGM00)); |
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231 | killagreg | 38 | |
39 | // Timer/Counter 0 Control Register B |
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40 | |||
41 | // set clock devider for timer 0 to SYSKLOCK/8 = 20MHz / 8 = 2.5MHz |
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42 | // i.e. the timer increments from 0x00 to 0xFF with an update rate of 2.5 MHz |
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43 | // hence the timer overflow interrupt frequency is 2.5 MHz / 256 = 9.765 kHz |
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44 | |||
45 | // divider 8 (Bits CS02 = 0, CS01 = 1, CS00 = 0) |
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46 | TCCR0B &= ~((1<<FOC0A)|(1<<FOC0B)|(1<<WGM02)); |
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47 | TCCR0B = (TCCR0B & 0xF8)|(0<<CS02)|(1<<CS01)|(0<<CS00); |
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48 | |||
49 | // init Timer/Counter 0 Register |
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50 | TCNT0 = 0; |
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51 | |||
52 | // Timer/Counter 0 Interrupt Mask Register |
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53 | // enable timer overflow interrupt only |
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54 | TIMSK0 &= ~((1<<OCIE0B)|(1<<OCIE0A)); |
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55 | TIMSK0 |= (1<<TOIE0); |
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56 | |||
274 | killagreg | 57 | |
58 | SystemTime.Year = 0; |
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59 | SystemTime.Month = 0; |
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60 | SystemTime.Day = 0; |
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61 | SystemTime.Hour = 0; |
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62 | SystemTime.Min = 0; |
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63 | SystemTime.Sec = 0; |
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64 | SystemTime.mSec = 0; |
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65 | SystemTime.Valid = 0; |
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66 | |||
67 | CountMilliseconds = 0; |
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68 | |||
69 | |||
231 | killagreg | 70 | SREG = sreg; |
71 | } |
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72 | |||
73 | |||
74 | |||
75 | /*****************************************************/ |
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76 | /* Interrupt Routine of Timer 0 */ |
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77 | /*****************************************************/ |
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78 | ISR(TIMER0_OVF_vect) // 9.765 kHz |
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79 | { |
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80 | static uint8_t cnt = 0; |
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271 | killagreg | 81 | #ifdef USE_FOLLOWME |
82 | uint8_t Beeper_On = 0; |
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83 | #endif |
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231 | killagreg | 84 | |
85 | if(!cnt--) // every 10th run (9.765kHz/10 = 976Hz) |
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86 | { |
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87 | cnt = 9; |
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88 | CountMilliseconds++; // increment millisecond counter |
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89 | } |
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271 | killagreg | 90 | |
91 | // beeper on if duration is not over |
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92 | if(BeepTime) |
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93 | { |
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94 | BeepTime--; // decrement BeepTime |
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95 | if(BeepTime & BeepModulation) Beeper_On = 1; |
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96 | else Beeper_On = 0; |
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97 | } |
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98 | else // beeper off if duration is over |
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99 | { |
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100 | Beeper_On = 0; |
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101 | BeepModulation = 0xFFFF; |
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102 | } |
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333 | killagreg | 103 | #ifdef USE_FOLLOWME |
271 | killagreg | 104 | // if beeper is on |
105 | if(Beeper_On) |
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106 | { |
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107 | // set speaker port to high |
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108 | PORTC |= (1<<PORTC7); // Speaker at PC7 |
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109 | } |
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110 | else // beeper is off |
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111 | { |
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112 | // set speaker port to low |
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113 | PORTC &= ~(1<<PORTC7);// Speaker at PC7 |
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114 | } |
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115 | #endif |
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231 | killagreg | 116 | } |
117 | |||
118 | |||
119 | // ----------------------------------------------------------------------- |
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120 | uint16_t SetDelay (uint16_t t) |
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121 | { |
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122 | return(CountMilliseconds + t - 1); |
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123 | } |
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124 | |||
125 | // ----------------------------------------------------------------------- |
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126 | int8_t CheckDelay(uint16_t t) |
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127 | { |
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128 | return(((t - CountMilliseconds) & 0x8000) >> 8); // check sign bit |
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129 | } |
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130 | |||
131 | // ----------------------------------------------------------------------- |
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132 | void Delay_ms(uint16_t w) |
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133 | { |
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134 | unsigned int t_stop; |
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135 | t_stop = SetDelay(w); |
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136 | while (!CheckDelay(t_stop)); |
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137 | } |
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138 |