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1 | /*####################################################################################### |
1 | /*####################################################################################### |
2 | Decodieren eines RC Summen Signals |
2 | Decodieren eines RC Summen Signals |
3 | #######################################################################################*/ |
3 | #######################################################################################*/ |
4 | // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
4 | // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
5 | // + Copyright (c) 04.2007 Holger Buss |
5 | // + Copyright (c) 04.2007 Holger Buss |
6 | // + only for non-profit use |
6 | // + only for non-profit use |
7 | // + www.MikroKopter.com |
7 | // + www.MikroKopter.com |
8 | // + see the File "License.txt" for further Informations |
8 | // + see the File "License.txt" for further Informations |
9 | // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
9 | // ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
10 | 10 | ||
11 | #include <stdlib.h> |
11 | #include <stdlib.h> |
12 | #include <avr/io.h> |
12 | #include <avr/io.h> |
13 | #include <avr/interrupt.h> |
13 | #include <avr/interrupt.h> |
14 | 14 | ||
15 | #include "rc.h" |
15 | #include "rc.h" |
16 | #include "main.h" |
16 | #include "main.h" |
17 | 17 | ||
18 | volatile int16_t PPM_in[15]; //PPM24 supports 12 channels per frame |
18 | volatile int16_t PPM_in[15]; //PPM24 supports 12 channels per frame |
19 | volatile int16_t PPM_diff[15]; |
19 | volatile int16_t PPM_diff[15]; |
20 | volatile uint8_t NewPpmData = 1; |
20 | volatile uint8_t NewPpmData = 1; |
21 | volatile int16_t RC_Quality = 0; |
21 | volatile int16_t RC_Quality = 0; |
22 | 22 | ||
23 | volatile uint8_t NewRCFrames = 0; |
23 | volatile uint8_t NewRCFrames = 0; |
24 | 24 | ||
25 | 25 | ||
26 | /***************************************************************/ |
26 | /***************************************************************/ |
27 | /* 16bit timer 1 is used to decode the PPM-Signal */ |
27 | /* 16bit timer 1 is used to decode the PPM-Signal */ |
28 | /***************************************************************/ |
28 | /***************************************************************/ |
29 | void RC_Init (void) |
29 | void RC_Init (void) |
30 | { |
30 | { |
31 | uint8_t sreg = SREG; |
31 | uint8_t sreg = SREG; |
32 | 32 | ||
33 | // disable all interrupts before reconfiguration |
33 | // disable all interrupts before reconfiguration |
34 | cli(); |
34 | cli(); |
35 | 35 | ||
36 | // PPM-signal is connected to the Input Capture Pin (PD6) of timer 1 |
36 | // PPM-signal is connected to the Input Capture Pin (PD6) of timer 1 |
37 | DDRD &= ~(1<<DDD6); |
37 | DDRD &= ~(1<<DDD6); |
38 | PORTD |= (1<<PORTD6); |
38 | PORTD |= (1<<PORTD6); |
39 | 39 | ||
40 | // Channel 5,6,7 is decoded to servo signals at pin PD5 (J3), PD4(J4), PD3(J5) |
40 | // Channel 5,6,7 is decoded to servo signals at pin PD5 (J3), PD4(J4), PD3(J5) |
41 | // set as output |
41 | // set as output |
42 | DDRD |= (1<<DDD5)|(1<<DDD4); |
42 | DDRD |= (1<<DDD5)|(1<<DDD4); |
43 | // low level |
43 | // low level |
44 | PORTD &= ~((1<<PORTD5)|(1<<PORTD4)); |
44 | PORTD &= ~((1<<PORTD5)|(1<<PORTD4)); |
45 | 45 | ||
46 | // PD3 can't be used in FC 1.1 if 2nd UART is activated |
46 | // PD3 can't be used in FC 1.1 if 2nd UART is activated |
47 | // because TXD1 is at that port |
47 | // because TXD1 is at that port |
48 | if(BoardRelease == 10) |
48 | if(BoardRelease == 10) |
49 | { |
49 | { |
50 | DDRD |= (1<<PORTD3); |
50 | DDRD |= (1<<PORTD3); |
51 | PORTD &= ~(1<<PORTD3); |
51 | PORTD &= ~(1<<PORTD3); |
52 | } |
52 | } |
53 | 53 | ||
54 | // Timer/Counter1 Control Register A, B, C |
54 | // Timer/Counter1 Control Register A, B, C |
55 | 55 | ||
56 | // Normal Mode (bits: WGM13=0, WGM12=0, WGM11=0, WGM10=0) |
56 | // Normal Mode (bits: WGM13=0, WGM12=0, WGM11=0, WGM10=0) |
57 | // Compare output pin A & B is disabled (bits: COM1A1=0, COM1A0=0, COM1B1=0, COM1B0=0) |
57 | // Compare output pin A & B is disabled (bits: COM1A1=0, COM1A0=0, COM1B1=0, COM1B0=0) |
58 | // Set clock source to SYSCLK/64 (bit: CS12=0, CS11=1, CS10=1) |
58 | // Set clock source to SYSCLK/64 (bit: CS12=0, CS11=1, CS10=1) |
59 | // Enable input capture noise cancler (bit: ICNC1=1) |
59 | // Enable input capture noise cancler (bit: ICNC1=1) |
60 | // Trigger on positive edge of the input capture pin (bit: ICES1=1), |
60 | // Trigger on positive edge of the input capture pin (bit: ICES1=1), |
61 | // Therefore the counter incremets at a clock of 20 MHz/64 = 312.5 kHz or 3.2µs |
61 | // Therefore the counter incremets at a clock of 20 MHz/64 = 312.5 kHz or 3.2µs |
62 | // The longest period is 0xFFFF / 312.5 kHz = 0.209712 s. |
62 | // The longest period is 0xFFFF / 312.5 kHz = 0.209712 s. |
63 | TCCR1A &= ~((1<<COM1A1)|(1<<COM1A0)|(1<<COM1B1)|(1<<COM1B0)|(1<<WGM11)|(1<<WGM10)); |
63 | TCCR1A &= ~((1<<COM1A1)|(1<<COM1A0)|(1<<COM1B1)|(1<<COM1B0)|(1<<WGM11)|(1<<WGM10)); |
64 | TCCR1B &= ~((1<<WGM13)|(1<<WGM12)|(1<<CS12)); |
64 | TCCR1B &= ~((1<<WGM13)|(1<<WGM12)|(1<<CS12)); |
65 | TCCR1B |= (1<<CS11)|(1<<CS10)|(1<<ICES1)|(1<<ICNC1); |
65 | TCCR1B |= (1<<CS11)|(1<<CS10)|(1<<ICES1)|(1<<ICNC1); |
66 | TCCR1C &= ~((1<<FOC1A)|(1<<FOC1B)); |
66 | TCCR1C &= ~((1<<FOC1A)|(1<<FOC1B)); |
67 | 67 | ||
68 | // Timer/Counter1 Interrupt Mask Register |
68 | // Timer/Counter1 Interrupt Mask Register |
69 | 69 | ||
70 | // Enable Input Capture Interrupt (bit: ICIE1=1) |
70 | // Enable Input Capture Interrupt (bit: ICIE1=1) |
71 | // Disable Output Compare A & B Match Interrupts (bit: OCIE1B=0, OICIE1A=0) |
71 | // Disable Output Compare A & B Match Interrupts (bit: OCIE1B=0, OICIE1A=0) |
72 | // Enable Overflow Interrupt (bit: TOIE1=0) |
72 | // Enable Overflow Interrupt (bit: TOIE1=0) |
73 | TIMSK1 &= ~((1<<OCIE1B)|(1<<OCIE1A)); |
73 | TIMSK1 &= ~((1<<OCIE1B)|(1<<OCIE1A)); |
74 | TIMSK1 |= (1<<ICIE1)|(1<<TOIE1); |
74 | TIMSK1 |= (1<<ICIE1)|(1<<TOIE1); |
75 | 75 | ||
76 | RC_Quality = 0; |
76 | RC_Quality = 0; |
77 | 77 | ||
78 | SREG = sreg; |
78 | SREG = sreg; |
79 | } |
79 | } |
80 | 80 | ||
81 | 81 | ||
82 | // happens every 0.209712 s. |
82 | // happens every 0.209712 s. |
83 | // check for at least one new frame per timer overflow (timeout) |
83 | // check for at least one new frame per timer overflow (timeout) |
84 | ISR(TIMER1_OVF_vect) |
84 | ISR(TIMER1_OVF_vect) |
85 | { |
85 | { |
86 | if (NewRCFrames == 0) RC_Quality /= 2; |
86 | if (NewRCFrames == 0) RC_Quality -= RC_Quality/8; |
87 | NewRCFrames = 0; |
87 | NewRCFrames = 0; |
88 | } |
88 | } |
89 | 89 | ||
90 | 90 | ||
91 | /********************************************************************/ |
91 | /********************************************************************/ |
92 | /* Every time a positive edge is detected at PD6 */ |
92 | /* Every time a positive edge is detected at PD6 */ |
93 | /********************************************************************/ |
93 | /********************************************************************/ |
94 | /* t-Frame |
94 | /* t-Frame |
95 | <-----------------------------------------------------------------------> |
95 | <-----------------------------------------------------------------------> |
96 | ____ ______ _____ ________ ______ sync gap ____ |
96 | ____ ______ _____ ________ ______ sync gap ____ |
97 | | | | | | | | | | | | |
97 | | | | | | | | | | | | |
98 | | | | | | | | | | | | |
98 | | | | | | | | | | | | |
99 | ___| |_| |_| |_| |_.............| |________________| |
99 | ___| |_| |_| |_| |_.............| |________________| |
100 | <-----><-------><------><--------> <------> <--- |
100 | <-----><-------><------><--------> <------> <--- |
101 | t0 t1 t2 t4 tn t0 |
101 | t0 t1 t2 t4 tn t0 |
102 | 102 | ||
103 | The PPM-Frame length is 22.5 ms. |
103 | The PPM-Frame length is 22.5 ms. |
104 | Channel high pulse width range is 0.7 ms to 1.7 ms completed by an 0.3 ms low pulse. |
104 | Channel high pulse width range is 0.7 ms to 1.7 ms completed by an 0.3 ms low pulse. |
105 | The mininimum time delay of two events coding a channel is ( 0.7 + 0.3) ms = 1 ms. |
105 | The mininimum time delay of two events coding a channel is ( 0.7 + 0.3) ms = 1 ms. |
106 | The maximum time delay of two events coding a chanel is ( 1.7 + 0.3) ms = 2 ms. |
106 | The maximum time delay of two events coding a chanel is ( 1.7 + 0.3) ms = 2 ms. |
107 | The minimum duration of all channels at minimum value is 8 * 1 ms = 8 ms. |
107 | The minimum duration of all channels at minimum value is 8 * 1 ms = 8 ms. |
108 | The maximum duration of all channels at maximum value is 8 * 2 ms = 16 ms. |
108 | The maximum duration of all channels at maximum value is 8 * 2 ms = 16 ms. |
109 | The remaining time of (22.5 - 8 ms) ms = 14.5 ms to (22.5 - 16 ms) ms = 6.5 ms is |
109 | The remaining time of (22.5 - 8 ms) ms = 14.5 ms to (22.5 - 16 ms) ms = 6.5 ms is |
110 | the syncronization gap. |
110 | the syncronization gap. |
111 | */ |
111 | */ |
112 | ISR(TIMER1_CAPT_vect) // typical rate of 1 ms to 2 ms |
112 | ISR(TIMER1_CAPT_vect) // typical rate of 1 ms to 2 ms |
113 | { |
113 | { |
114 | int16_t signal = 0, tmp; |
114 | int16_t signal = 0, tmp; |
115 | static int16_t index; |
115 | static int16_t index; |
116 | static uint16_t oldICR1 = 0; |
116 | static uint16_t oldICR1 = 0; |
117 | 117 | ||
118 | // 16bit Input Capture Register ICR1 contains the timer value TCNT1 |
118 | // 16bit Input Capture Register ICR1 contains the timer value TCNT1 |
119 | // at the time the edge was detected |
119 | // at the time the edge was detected |
120 | 120 | ||
121 | // calculate the time delay to the previous event time which is stored in oldICR1 |
121 | // calculate the time delay to the previous event time which is stored in oldICR1 |
122 | // calculatiing the difference of the two uint16_t and converting the result to an int16_t |
122 | // calculatiing the difference of the two uint16_t and converting the result to an int16_t |
123 | // implicit handles a timer overflow 65535 -> 0 the right way. |
123 | // implicit handles a timer overflow 65535 -> 0 the right way. |
124 | signal = (uint16_t) ICR1 - oldICR1; |
124 | signal = (uint16_t) ICR1 - oldICR1; |
125 | oldICR1 = ICR1; |
125 | oldICR1 = ICR1; |
126 | 126 | ||
127 | //sync gap? (3.52 ms < signal < 25.6 ms) |
127 | //sync gap? (3.52 ms < signal < 25.6 ms) |
128 | if((signal > 1100) && (signal < 8000)) |
128 | if((signal > 1100) && (signal < 8000)) |
129 | { |
129 | { |
130 | // if a sync gap happens and there where at least 4 channels decoded before |
130 | // if a sync gap happens and there where at least 4 channels decoded before |
131 | // then the NewPpmData flag is reset indicating valid data in the PPM_in[] array. |
131 | // then the NewPpmData flag is reset indicating valid data in the PPM_in[] array. |
132 | if(index >= 4) |
132 | if(index >= 4) |
133 | { |
133 | { |
134 | NewPpmData = 0; // Null means NewData for the first 4 channels |
134 | NewPpmData = 0; // Null means NewData for the first 4 channels |
135 | NewRCFrames++; |
135 | NewRCFrames++; |
136 | } |
136 | } |
137 | // synchronize channel index |
137 | // synchronize channel index |
138 | index = 1; |
138 | index = 1; |
139 | } |
139 | } |
140 | else // within the PPM frame |
140 | else // within the PPM frame |
141 | { |
141 | { |
142 | if(index < 14) // PPM24 supports 12 channels |
142 | if(index < 14) // PPM24 supports 12 channels |
143 | { |
143 | { |
144 | // check for valid signal length (0.8 ms < signal < 2.1984 ms) |
144 | // check for valid signal length (0.8 ms < signal < 2.1984 ms) |
145 | // signal range is from 1.0ms/3.2us = 312 to 2.0ms/3.2us = 625 |
145 | // signal range is from 1.0ms/3.2us = 312 to 2.0ms/3.2us = 625 |
146 | if((signal > 250) && (signal < 687)) |
146 | if((signal > 250) && (signal < 687)) |
147 | { |
147 | { |
148 | // shift signal to zero symmetric range -154 to 159 |
148 | // shift signal to zero symmetric range -154 to 159 |
149 | signal -= 466; // offset of 1.4912 ms ??? (469 * 3.2µs = 1.5008 ms) |
149 | signal -= 466; // offset of 1.4912 ms ??? (469 * 3.2µs = 1.5008 ms) |
150 | // check for stable signal |
150 | // check for stable signal |
151 | if(abs(signal-PPM_in[index]) < 6) |
151 | if(abs(signal-PPM_in[index]) < 6) |
152 | { |
152 | { |
153 | if(RC_Quality < 200) RC_Quality +=10; |
153 | if(RC_Quality < 200) RC_Quality +=10; |
154 | } |
154 | } |
155 | // calculate exponential history for signal |
155 | // calculate exponential history for signal |
156 | tmp = (3 * (PPM_in[index]) + signal) / 4; |
156 | tmp = (3 * (PPM_in[index]) + signal) / 4; |
157 | if(tmp > signal+1) tmp--; else |
157 | if(tmp > signal+1) tmp--; else |
158 | if(tmp < signal-1) tmp++; |
158 | if(tmp < signal-1) tmp++; |
159 | // calculate signal difference on good signal level |
159 | // calculate signal difference on good signal level |
160 | if(RC_Quality >= 195) PPM_diff[index] = ((tmp - PPM_in[index]) / 3) * 3; // cut off lower 3 bit for nois reduction |
160 | if(RC_Quality >= 195) PPM_diff[index] = ((tmp - PPM_in[index]) / 3) * 3; // cut off lower 3 bit for nois reduction |
161 | else PPM_diff[index] = 0; |
161 | else PPM_diff[index] = 0; |
162 | PPM_in[index] = tmp; // update channel value |
162 | PPM_in[index] = tmp; // update channel value |
163 | } |
163 | } |
164 | index++; // next channel |
164 | index++; // next channel |
165 | // demux sum signal for channels 5 to 7 to J3, J4, J5 |
165 | // demux sum signal for channels 5 to 7 to J3, J4, J5 |
166 | if(index == 5) PORTD |= (1<<PORTD5); else PORTD &= ~(1<<PORTD5); |
166 | if(index == 5) PORTD |= (1<<PORTD5); else PORTD &= ~(1<<PORTD5); |
167 | if(index == 6) PORTD |= (1<<PORTD4); else PORTD &= ~(1<<PORTD4); |
167 | if(index == 6) PORTD |= (1<<PORTD4); else PORTD &= ~(1<<PORTD4); |
168 | if(BoardRelease == 10) |
168 | if(BoardRelease == 10) |
169 | { |
169 | { |
170 | if(index == 7) PORTD |= (1<<PORTD3); else PORTD &= ~(1<<PORTD3); |
170 | if(index == 7) PORTD |= (1<<PORTD3); else PORTD &= ~(1<<PORTD3); |
171 | } |
171 | } |
172 | } |
172 | } |
173 | } |
173 | } |
174 | if(RC_Quality) RC_Quality--; |
174 | if(RC_Quality) RC_Quality--; |
175 | } |
175 | } |
176 | 176 | ||
177 | 177 | ||
178 | 178 | ||
179 | 179 | ||
180 | 180 | ||
181 | 181 |