robobuggy / arduino / RadioBuggyMega / receiver.c @ 5ea63f0d
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1 | 0c873a67 | msebek | /**
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2 | e6c4b5e0 | Matt Sebek | * @file receiver.c
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3 | 0c873a67 | msebek | * @brief Contains Code for dealing with RC Receiver
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4 | * NOTE: AIL and THR are flipped.
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5 | * AIL is on pin 2
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6 | * THR is on pin 3
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7 | e6c4b5e0 | Matt Sebek | *
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8 | * @author Matt Sebek (msebek)
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9 | * @author Zach Dawson (zsd)
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10 | 0c873a67 | msebek | */
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11 | #include <Arduino.h> |
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12 | #include "receiver.h" |
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13 | |||
14 | |||
15 | #define AIL_LEFTMOST 2000 |
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16 | #define AIL_RIGHTMOST 980 |
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17 | #define AIL_CENTERMOST 1480 |
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18 | |||
19 | #define THR_LEFTMOST -1 |
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20 | #define THR_RIGHTMOST -1 |
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21 | #define THR_CENTERMOST -1 |
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22 | |||
23 | eb7af729 | unknown | #define AIL_RECEIVER_PIN 2 |
24 | #define AIL_RECEIVER_INT 0 |
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25 | 0c873a67 | msebek | |
26 | eb7af729 | unknown | #define THR_RECEIVER_PIN 3 |
27 | #define THR_RECEIVER_INT 1 |
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28 | |||
29 | 5ea63f0d | unknown | //For 72 MHz RC reciever
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30 | //#define PWM_TIME 21800
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31 | //#define PWM_THRESH 130
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32 | //#define BIG_PULSE 10
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33 | //High pulse lasts over 1/10 of period
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34 | //#define SHORT_PULSE 21
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35 | //High pulse lasts under 1/21 of period
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36 | |||
37 | //For 2.4 GHz racecar reciever
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38 | #define PWM_TIME 18370 |
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39 | eb7af729 | unknown | #define PWM_THRESH 130 |
40 | 5ea63f0d | unknown | #define BIG_PULSE 8 |
41 | //High pulse lasts over 1/8 of period
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42 | #define SHORT_PULSE 19 |
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43 | //High pulse lasts under 1/19 of period
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44 | 0c873a67 | msebek | |
45 | e6c4b5e0 | Matt Sebek | // Defined in receiver.h
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46 | // #define THR_INDEX 0
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47 | // #define AIL_INDEX 1
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48 | 0c873a67 | msebek | |
49 | // Note: arr[0] is thr, arr[1] is ail
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50 | |||
51 | eb7af729 | unknown | static volatile unsigned long up_switch_time[2]; |
52 | static volatile unsigned long down_switch_time[2]; |
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53 | static volatile unsigned long rc_value[2]; |
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54 | 0c873a67 | msebek | |
55 | eb7af729 | unknown | // NOTE THAT WE ARE ASSUMING:
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56 | // Main Loop-length is shorter than PWM pulse length.
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57 | // Otherwise, you could recieve stale values in your main loop.
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58 | // Loop reading rc_values must set rc_available false after reading
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59 | 0c873a67 | msebek | // When our code gets really busy this will become inaccurate,
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60 | // (i believe since micros gets shifted a bit) but for
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61 | // the current application its easy to understand and works very well
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62 | // TODO if things start twitching, move to using registers directly.
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63 | e6c4b5e0 | Matt Sebek | // TODO if this starts twitching, also micros has a resolution of 4us.
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64 | 0c873a67 | msebek | static void receiver_on_ail_interrupt() { |
65 | if(digitalRead(AIL_RECEIVER_PIN) == HIGH) {
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66 | eb7af729 | unknown | // High Received
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67 | if((micros() - up_switch_time[AIL_INDEX] > PWM_TIME - PWM_THRESH) &&
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68 | (micros() - up_switch_time[AIL_INDEX] < PWM_TIME + PWM_THRESH)) { |
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69 | // TODO this prevent an instantaneous start-up error, where the
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70 | // above condition is true, and up_switch_time
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71 | if((down_switch_time[AIL_INDEX] > up_switch_time[AIL_INDEX]) &&
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72 | (rc_available[AIL_INDEX] == 0)) {
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73 | rc_value[AIL_INDEX] = (down_switch_time[AIL_INDEX] - |
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74 | up_switch_time[AIL_INDEX]); |
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75 | rc_available[AIL_INDEX] = 1;
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76 | 5ea63f0d | unknown | if(rc_value[AIL_INDEX]/(PWM_TIME/BIG_PULSE) >= 1 || rc_value[AIL_INDEX]/(PWM_TIME/SHORT_PULSE) == 0) |
77 | eb7af729 | unknown | rc_available[AIL_INDEX] == 0;
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78 | } |
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79 | } |
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80 | up_switch_time[AIL_INDEX] = micros(); |
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81 | 0c873a67 | msebek | } else {
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82 | eb7af729 | unknown | // Low received
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83 | if(up_switch_time[AIL_INDEX]) {
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84 | down_switch_time[AIL_INDEX] = micros(); |
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85 | 0c873a67 | msebek | } |
86 | } |
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87 | } |
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88 | |||
89 | static void receiver_on_thr_interrupt() { |
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90 | if(digitalRead(THR_RECEIVER_PIN) == HIGH) {
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91 | eb7af729 | unknown | // High Received
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92 | if((micros() - up_switch_time[THR_INDEX] > PWM_TIME - PWM_THRESH) &&
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93 | (micros() - up_switch_time[THR_INDEX] < PWM_TIME + PWM_THRESH)) { |
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94 | // TODO this prevent an instantaneous start-up error, where the
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95 | // above condition is true, and up_switch_time
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96 | if((down_switch_time[THR_INDEX] > up_switch_time[THR_INDEX]) &&
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97 | (rc_available[THR_INDEX] == 0)) {
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98 | rc_value[THR_INDEX] = (down_switch_time[THR_INDEX] - |
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99 | up_switch_time[THR_INDEX]); |
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100 | rc_available[THR_INDEX] = 1;
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101 | if(rc_value[THR_INDEX]/(PWM_TIME/10) >= 1 || rc_value[THR_INDEX]/(PWM_TIME/21) == 0) |
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102 | rc_available[THR_INDEX] == 0;
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103 | } |
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104 | } |
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105 | up_switch_time[THR_INDEX] = micros(); |
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106 | 0c873a67 | msebek | } else {
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107 | eb7af729 | unknown | // Low received
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108 | if(up_switch_time[THR_INDEX]) {
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109 | down_switch_time[THR_INDEX] = micros(); |
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110 | 0c873a67 | msebek | } |
111 | } |
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112 | } |
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113 | |||
114 | // Returns error code
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115 | int receiver_init() {
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116 | eb7af729 | unknown | up_switch_time[0] = 0; |
117 | up_switch_time[1] = 0; |
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118 | down_switch_time[0] = 0; |
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119 | down_switch_time[1] = 0; |
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120 | 0c873a67 | msebek | attachInterrupt(THR_RECEIVER_INT, receiver_on_thr_interrupt, CHANGE); |
121 | attachInterrupt(AIL_RECEIVER_INT, receiver_on_ail_interrupt, CHANGE); |
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122 | } |
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123 | |||
124 | |||
125 | // Index = 0 to check thr, index = 1 to check
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126 | // Returns 0 to 180, with 90 being center.
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127 | // TODO measure throttle positions.
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128 | int receiver_get_angle(int index) { |
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129 | // Math to convert nThrottleIn to 0-180.
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130 | eb7af729 | unknown | int ret_val = (int)(rc_value[index]-AIL_RIGHTMOST)*3/17; |
131 | 0c873a67 | msebek | rc_available[index] = 0;
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132 | return ret_val;
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133 | } |
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134 | eb7af729 | unknown | |
135 | |||
136 |