1 | /// Includes //////////
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2 | #include <avr/io.h>
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3 | #include <avr/interrupt.h>
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4 |
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5 | /// Data Types /////////
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6 | typedef unsigned char u8;
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7 | typedef unsigned int u16;
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8 | typedef struct task
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9 | {
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10 | // pointer to a function
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11 | void (*pfunc) (void);
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12 | // delay before the first call
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13 | u16 delay;
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14 | // interval between subsequent runs
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15 | u16 period;
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16 | // flag indicating time to run
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17 | u8 run;
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18 | }task;
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19 |
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20 | struct USART
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21 | { unsigned char empfangen;
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22 | unsigned char wert;
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23 | }
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24 |
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25 | /// Defines ///////////
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26 | // 25msec period 256-180
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27 | // 7.3728MHz and /1024 prescaler
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28 | #define StartFrom 76
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29 | // maximum number of tasks
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30 | #define MAXnTASKS 20
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31 |
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32 | /// Globals ///////////
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33 | volatile task TaskArray[MAXnTASKS];
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34 |
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35 | /// Prototypes ////////
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36 | void InitUART (u16 baud);
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37 | void TransmitByte (u8 data);
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38 | void InitScheduler (void);
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39 | void UpdateScheduler(void);
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40 | void DeleteTask (u8 index);
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41 | void AddTask (void (*taskfunc)(void), u16 taskdelay, u16 taskperiod);
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42 | void DispatchTask (void);
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43 |
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44 | void TestA (void);
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45 | void TestB (void);
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46 | void TestC (void);
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47 |
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48 | /// Main //////////////
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49 | int main(void)
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50 | {
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51 | InitUART (23);
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52 | InitScheduler();
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53 |
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54 | // populate task array
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55 | AddTask (TestA, 0, 3);
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56 | AddTask (TestB, 1, 4);
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57 | AddTask (TestC, 4, 0);
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58 |
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59 | // enable interrupts
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60 | sei();
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61 |
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62 | while (1)
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63 | {
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64 | DispatchTask();
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65 | }
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66 | }
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67 |
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68 | void InitUART (u16 baud)
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69 | {
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70 | UBRRH = (u8)(baud>>8);
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71 | UBRRL = (u8)baud;
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72 | UCSRB = (1<<RXEN)|(1<<TXEN);
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73 | UCSRC = (1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0);
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74 | //hier ist noch der Recieveinterrupt zu aktivieren
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75 | }
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76 |
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77 |
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78 |
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79 | void InitScheduler (void)
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80 | {
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81 | u8 i;
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82 |
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83 | // timer prescaler clock/1024
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84 | TCCR0 |= (1<<CS02)|(1<<CS00);
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85 | // clear pending interrupts
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86 | TIFR = 1<<TOV0;
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87 | // enable timer0 overflow interrupt
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88 | TIMSK |= 1<<TOIE0;
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89 | // load timer0
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90 | TCNT0 = StartFrom;
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91 |
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92 | // clear task array
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93 | for (i=0; i<MAXnTASKS; i++) DeleteTask(i);
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94 | }
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95 |
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96 | void DeleteTask (u8 j)
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97 | {
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98 | TaskArray[j].pfunc = 0x0000;
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99 | TaskArray[j].delay = 0;
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100 | TaskArray[j].period = 0;
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101 | TaskArray[j].run = 0;
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102 | }
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103 |
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104 | void AddTask (void (*taskfunc)(void), u16 taskdelay, u16 taskperiod)
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105 | {
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106 | u8 n=0;
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107 |
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108 | // find next available position
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109 | while ((TaskArray[n].pfunc != 0) && (n < MAXnTASKS)) n++;
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110 |
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111 | // place task
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112 | if (n < MAXnTASKS)
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113 | {
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114 | TaskArray[n].pfunc = taskfunc;
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115 | TaskArray[n].delay = taskdelay;
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116 | TaskArray[n].period = taskperiod;
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117 | TaskArray[n].run = 0;
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118 | }
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119 | }
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120 |
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121 | SIGNAL(SIG_OVERFLOW0)
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122 | {
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123 | u8 m;
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124 |
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125 |
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126 |
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127 | // load timer
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128 | TCNT0 = StartFrom;
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129 |
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130 | for (m=0; m<MAXnTASKS; m++)
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131 | {
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132 | if (TaskArray[m].pfunc)
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133 | {
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134 | if (TaskArray[m].delay == 0)
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135 | {
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136 | TaskArray[m].run = 1;
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137 | TaskArray[m].delay = TaskArray[m].period;
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138 | }
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139 | else TaskArray[m].delay--;
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140 | }
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141 | }
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142 | }
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143 | ISR(USART_RECv_vect)
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144 | {
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145 | USART.empfangen=1;
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146 | USART.wert=UDR;
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147 | }
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148 | void DispatchTask (void)
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149 | {
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150 | u8 k;
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151 |
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152 | for (k=0; k<MAXnTASKS; k++)
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153 | {
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154 | if (TaskArray[k].run == 1)
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155 | {
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156 | // run task
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157 | (*TaskArray[k].pfunc)();
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158 | // clear run flag
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159 | TaskArray[k].run = 0;
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160 | }
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161 | }
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162 |
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163 | }
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164 |
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165 | void TestA (void)
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166 | {
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167 |
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168 | }
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169 |
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170 | void TestB (void)
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171 | {
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172 |
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173 | }
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174 |
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175 | void TestC (void)
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176 | {
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177 | //Abfrage, ob was Empfangen
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178 |
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179 | if(USART.empfangen){
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180 | // hier geschieht die Verarbeitung
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181 |
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182 |
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183 | //Ende der Verarbeitung
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184 | USART.empfangen=0;
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185 | }
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186 | }
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