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1 | ingob | 1 | /*####################################################################################### |
685 | killagreg | 2 | Decodieren eines RC Summen Signals |
1 | ingob | 3 | #######################################################################################*/ |
4 | // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
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5 | // + Copyright (c) 04.2007 Holger Buss |
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6 | // + only for non-profit use |
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7 | // + www.MikroKopter.com |
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8 | // + see the File "License.txt" for further Informations |
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9 | // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
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10 | |||
687 | killagreg | 11 | #include <stdlib.h> |
685 | killagreg | 12 | #include <avr/io.h> |
13 | #include <avr/interrupt.h> |
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14 | |||
1 | ingob | 15 | #include "rc.h" |
732 | killagreg | 16 | #include "main.h" |
1 | ingob | 17 | |
761 | killagreg | 18 | volatile int16_t PPM_in[15]; //PPM24 supports 12 channels per frame |
19 | volatile int16_t PPM_diff[15]; |
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687 | killagreg | 20 | volatile uint8_t NewPpmData = 1; |
801 | killagreg | 21 | volatile int16_t RC_Quality = 0; |
1 | ingob | 22 | |
800 | killagreg | 23 | |
687 | killagreg | 24 | /***************************************************************/ |
688 | killagreg | 25 | /* 16bit timer 1 is used to decode the PPM-Signal */ |
687 | killagreg | 26 | /***************************************************************/ |
712 | killagreg | 27 | void RC_Init (void) |
1 | ingob | 28 | { |
688 | killagreg | 29 | uint8_t sreg = SREG; |
1 | ingob | 30 | |
688 | killagreg | 31 | // disable all interrupts before reconfiguration |
32 | cli(); |
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685 | killagreg | 33 | |
688 | killagreg | 34 | // PPM-signal is connected to the Input Capture Pin (PD6) of timer 1 |
35 | DDRD &= ~(1<<DDD6); |
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36 | PORTD |= (1<<PORTD6); |
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37 | |||
689 | killagreg | 38 | // Channel 5,6,7 is decoded to servo signals at pin PD5 (J3), PD4(J4), PD3(J5) |
39 | // set as output |
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756 | killagreg | 40 | DDRD |= (1<<DDD5)|(1<<DDD4); |
689 | killagreg | 41 | // low level |
756 | killagreg | 42 | PORTD &= ~((1<<PORTD5)|(1<<PORTD4)); |
689 | killagreg | 43 | |
732 | killagreg | 44 | // PD3 can't be used in FC 1.1 if 2nd UART is activated |
766 | killagreg | 45 | // because TXD1 is at that port |
732 | killagreg | 46 | if(BoardRelease == 10) |
47 | { |
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48 | DDRD |= (1<<PORTD3); |
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49 | PORTD &= ~(1<<PORTD3); |
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50 | } |
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51 | |||
688 | killagreg | 52 | // Timer/Counter1 Control Register A, B, C |
53 | |||
54 | // Normal Mode (bits: WGM13=0, WGM12=0, WGM11=0, WGM10=0) |
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55 | // Compare output pin A & B is disabled (bits: COM1A1=0, COM1A0=0, COM1B1=0, COM1B0=0) |
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56 | // Set clock source to SYSCLK/64 (bit: CS12=0, CS11=1, CS10=1) |
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57 | // Enable input capture noise cancler (bit: ICNC1=1) |
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58 | // Trigger on positive edge of the input capture pin (bit: ICES1=1), |
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59 | // Therefore the counter incremets at a clock of 20 MHz/64 = 312.5 kHz or 3.2µs |
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60 | // The longest period is 0xFFFF / 312.5 kHz = 0.209712 s. |
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61 | TCCR1A &= ~((1<<COM1A1)|(1<<COM1A0)|(1<<COM1B1)|(1<<COM1B0)|(1<<WGM11)|(1<<WGM10)); |
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62 | TCCR1B &= ~((1<<WGM13)|(1<<WGM12)|(1<<CS12)); |
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63 | TCCR1B |= (1<<CS11)|(1<<CS10)|(1<<ICES1)|(1<<ICNC1); |
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64 | TCCR1C &= ~((1<<FOC1A)|(1<<FOC1B)); |
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65 | |||
66 | // Timer/Counter1 Interrupt Mask Register |
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67 | |||
68 | // Enable Input Capture Interrupt (bit: ICIE1=1) |
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69 | // Disable Output Compare A & B Match Interrupts (bit: OCIE1B=0, OICIE1A=0) |
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70 | // Disable Overflow Interrupt (bit: TOIE1=0) |
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71 | TIMSK1 &= ~((1<<OCIE1B)|(1<<OCIE1A)|(1<<TOIE1)); |
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72 | TIMSK1 |= (1<<ICIE1); |
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73 | |||
800 | killagreg | 74 | RC_Quality = 0; |
75 | |||
688 | killagreg | 76 | SREG = sreg; |
1 | ingob | 77 | } |
78 | |||
79 | |||
688 | killagreg | 80 | /********************************************************************/ |
81 | /* Every time a positive edge is detected at PD6 */ |
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82 | /********************************************************************/ |
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761 | killagreg | 83 | /* t-Frame |
84 | <-----------------------------------------------------------------------> |
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85 | ____ ______ _____ ________ ______ sync gap ____ |
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86 | | | | | | | | | | | | |
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87 | | | | | | | | | | | | |
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88 | ___| |_| |_| |_| |_.............| |________________| |
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89 | <-----><-------><------><--------> <------> <--- |
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90 | t0 t1 t2 t4 tn t0 |
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91 | |||
688 | killagreg | 92 | The PPM-Frame length is 22.5 ms. |
93 | Channel high pulse width range is 0.7 ms to 1.7 ms completed by an 0.3 ms low pulse. |
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94 | The mininimum time delay of two events coding a channel is ( 0.7 + 0.3) ms = 1 ms. |
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95 | The maximum time delay of two events coding a chanel is ( 1.7 + 0.3) ms = 2 ms. |
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96 | The minimum duration of all channels at minimum value is 8 * 1 ms = 8 ms. |
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97 | The maximum duration of all channels at maximum value is 8 * 2 ms = 16 ms. |
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98 | The remaining time of (22.5 - 8 ms) ms = 14.5 ms to (22.5 - 16 ms) ms = 6.5 ms is |
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99 | the syncronization gap. |
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100 | */ |
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101 | ISR(TIMER1_CAPT_vect) // typical rate of 1 ms to 2 ms |
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1 | ingob | 102 | { |
688 | killagreg | 103 | static uint16_t oldICR1 = 0; |
104 | int16_t signal = 0, tmp; |
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105 | static int16_t index; |
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800 | killagreg | 106 | static int16_t Sum_RC_Quality = 0; |
801 | killagreg | 107 | int16_t Noise; |
685 | killagreg | 108 | |
688 | killagreg | 109 | // 16bit Input Capture Register ICR1 contains the timer value TCNT1 |
110 | // at the time the edge was detected |
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685 | killagreg | 111 | |
688 | killagreg | 112 | // calculate the time delay to the previous event time which is stored in oldICR1 |
800 | killagreg | 113 | // calculatiing the difference of the two uint16_t and converting the result to an int16_t |
114 | // implicit handles a timer overflow 65535 -> 0 the right way. |
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688 | killagreg | 115 | signal = (uint16_t) ICR1 - oldICR1; |
116 | oldICR1 = ICR1; |
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117 | |||
118 | |||
119 | //sync gap? (3.52 ms < signal < 25.6 ms) |
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685 | killagreg | 120 | if((signal > 1100) && (signal < 8000)) |
688 | killagreg | 121 | { |
122 | // if a sync gap happens and there where at least 4 channels decoded before |
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123 | // then the NewPpmData flag is reset indicating valid data in the PPM_in[] array. |
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762 | killagreg | 124 | if(index >= 4) NewPpmData = 0; // Null means NewData for the first 4 channels |
688 | killagreg | 125 | // synchronize channel index |
126 | index = 1; |
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127 | } |
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128 | else // within the PPM frame |
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1 | ingob | 129 | { |
761 | killagreg | 130 | if(index < 14) // PPM24 supports 12 channels |
1 | ingob | 131 | { |
688 | killagreg | 132 | // check for valid signal length (0.8 ms < signal < 2.1984 ms) |
711 | killagreg | 133 | // signal range is from 1.0ms/3.2us = 312 to 2.0ms/3.2us = 625 |
688 | killagreg | 134 | if((signal > 250) && (signal < 687)) |
1 | ingob | 135 | { |
711 | killagreg | 136 | // shift signal to zero symmetric range -154 to 159 |
688 | killagreg | 137 | signal -= 466; // offset of 1.4912 ms ??? (469 * 3.2µs = 1.5008 ms) |
138 | // check for stable signal |
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801 | killagreg | 139 | Noise = abs(signal - PPM_in[index]); |
140 | if((Noise/16) > (200-RC_Quality)) // spike detector |
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141 | { |
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142 | Sum_RC_Quality -= 3*RC_Quality; |
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143 | Sum_RC_Quality += 3*(200 - Noise); |
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144 | } |
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145 | else |
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146 | { |
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147 | Sum_RC_Quality -= RC_Quality; |
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148 | Sum_RC_Quality += 200 - Noise; |
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149 | } |
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688 | killagreg | 150 | // calculate exponential history for signal |
685 | killagreg | 151 | tmp = (3 * (PPM_in[index]) + signal) / 4; |
604 | hbuss | 152 | if(tmp > signal+1) tmp--; else |
685 | killagreg | 153 | if(tmp < signal-1) tmp++; |
688 | killagreg | 154 | // calculate signal difference on good signal level |
800 | killagreg | 155 | if(RC_Quality >= 170) PPM_diff[index] = ((tmp - PPM_in[index]) / 3) * 3; // cut off lower 3 bit for nois reduction |
604 | hbuss | 156 | else PPM_diff[index] = 0; |
688 | killagreg | 157 | PPM_in[index] = tmp; // update channel value |
158 | } |
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800 | killagreg | 159 | else |
160 | { // invalid PPM time |
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161 | Sum_RC_Quality -= Sum_RC_Quality/4; |
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162 | } |
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163 | if(Sum_RC_Quality < 0) Sum_RC_Quality = 0; |
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801 | killagreg | 164 | RC_Quality = Sum_RC_Quality/128; |
688 | killagreg | 165 | index++; // next channel |
689 | killagreg | 166 | // demux sum signal for channels 5 to 7 to J3, J4, J5 |
167 | if(index == 5) PORTD |= (1<<PORTD5); else PORTD &= ~(1<<PORTD5); |
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757 | killagreg | 168 | if(index == 6) PORTD |= (1<<PORTD4); else PORTD &= ~(1<<PORTD4); |
732 | killagreg | 169 | if(BoardRelease == 10) |
170 | { |
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171 | if(index == 7) PORTD |= (1<<PORTD3); else PORTD &= ~(1<<PORTD3); |
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172 | } |
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1 | ingob | 173 | } |
174 | } |
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175 | } |
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176 | |||
177 | |||
178 | |||
179 | |||
180 |