Revision eb7af729
Arduino code measures PWM up and PWM down time, and if U+D!= contant, we reject the signal
| arduino/RadioBuggyMega/receiver.c | ||
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| 20 | 20 |
#define THR_RIGHTMOST -1 |
| 21 | 21 |
#define THR_CENTERMOST -1 |
| 22 | 22 |
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#define AIL_RECEIVER_PIN 3
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#define AIL_RECEIVER_INT 1
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#define AIL_RECEIVER_PIN 2
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#define AIL_RECEIVER_INT 0
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| 25 | 25 |
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#define THR_RECEIVER_PIN 2 |
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#define THR_RECEIVER_INT 0 |
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#define THR_RECEIVER_PIN 3 |
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#define THR_RECEIVER_INT 1 |
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#define PWM_TIME 21800 |
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#define PWM_THRESH 130 |
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| 28 | 31 |
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// Defined in receiver.h |
| 30 | 33 |
// #define THR_INDEX 0 |
| 31 | 34 |
// #define AIL_INDEX 1 |
| 32 | 35 |
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// Note: arr[0] is thr, arr[1] is ail |
| 34 |
static volatile unsigned long start_time[2]; |
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static volatile unsigned long rc_value[2]; |
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| 36 | 37 |
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static volatile unsigned long up_switch_time[2]; |
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static volatile unsigned long down_switch_time[2]; |
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static volatile unsigned long rc_value[2]; |
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// NOTE THAT WE ARE ASSUMING: |
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// Main Loop-length is shorter than PWM pulse length. |
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// Otherwise, you could recieve stale values in your main loop. |
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// Loop reading rc_values must set rc_available false after reading |
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| 38 | 46 |
// When our code gets really busy this will become inaccurate, |
| 39 | 47 |
// (i believe since micros gets shifted a bit) but for |
| 40 | 48 |
// the current application its easy to understand and works very well |
| ... | ... | |
| 42 | 50 |
// TODO if this starts twitching, also micros has a resolution of 4us. |
| 43 | 51 |
static void receiver_on_ail_interrupt() {
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| 44 | 52 |
if(digitalRead(AIL_RECEIVER_PIN) == HIGH) {
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start_time[AIL_INDEX] = micros(); |
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// High Received |
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if((micros() - up_switch_time[AIL_INDEX] > PWM_TIME - PWM_THRESH) && |
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(micros() - up_switch_time[AIL_INDEX] < PWM_TIME + PWM_THRESH)) {
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// TODO this prevent an instantaneous start-up error, where the |
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// above condition is true, and up_switch_time |
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if((down_switch_time[AIL_INDEX] > up_switch_time[AIL_INDEX]) && |
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(rc_available[AIL_INDEX] == 0)) {
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rc_value[AIL_INDEX] = (down_switch_time[AIL_INDEX] - |
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up_switch_time[AIL_INDEX]); |
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rc_available[AIL_INDEX] = 1; |
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if(rc_value[AIL_INDEX]/(PWM_TIME/10) >= 1 || rc_value[AIL_INDEX]/(PWM_TIME/21) == 0) |
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rc_available[AIL_INDEX] == 0; |
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} |
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} |
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up_switch_time[AIL_INDEX] = micros(); |
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| 46 | 68 |
} else {
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if(start_time[AIL_INDEX] && (rc_available[AIL_INDEX] == 0)) {
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rc_value[AIL_INDEX] = (micros() - start_time[AIL_INDEX]); |
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start_time[AIL_INDEX] = 0; |
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rc_available[AIL_INDEX] = 1; |
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// Low received |
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if(up_switch_time[AIL_INDEX]) {
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down_switch_time[AIL_INDEX] = micros(); |
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| 51 | 72 |
} |
| 52 | 73 |
} |
| 53 | 74 |
} |
| 54 | 75 |
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| 55 | 76 |
static void receiver_on_thr_interrupt() {
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| 56 | 77 |
if(digitalRead(THR_RECEIVER_PIN) == HIGH) {
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start_time[THR_INDEX] = micros(); |
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// High Received |
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if((micros() - up_switch_time[THR_INDEX] > PWM_TIME - PWM_THRESH) && |
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(micros() - up_switch_time[THR_INDEX] < PWM_TIME + PWM_THRESH)) {
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// TODO this prevent an instantaneous start-up error, where the |
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// above condition is true, and up_switch_time |
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if((down_switch_time[THR_INDEX] > up_switch_time[THR_INDEX]) && |
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(rc_available[THR_INDEX] == 0)) {
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rc_value[THR_INDEX] = (down_switch_time[THR_INDEX] - |
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up_switch_time[THR_INDEX]); |
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rc_available[THR_INDEX] = 1; |
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if(rc_value[THR_INDEX]/(PWM_TIME/10) >= 1 || rc_value[THR_INDEX]/(PWM_TIME/21) == 0) |
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rc_available[THR_INDEX] == 0; |
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} |
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} |
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up_switch_time[THR_INDEX] = micros(); |
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| 58 | 93 |
} else {
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if(start_time[THR_INDEX] && (rc_available[THR_INDEX] == 0)) {
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rc_value[THR_INDEX] = (int)(micros() - start_time[THR_INDEX]); |
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start_time[THR_INDEX] = 0; |
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rc_available[THR_INDEX] = 1; |
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// Low received |
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if(up_switch_time[THR_INDEX]) {
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down_switch_time[THR_INDEX] = micros(); |
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| 63 | 97 |
} |
| 64 | 98 |
} |
| 65 | 99 |
} |
| 66 | 100 |
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// Returns error code |
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int receiver_init() {
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up_switch_time[0] = 0; |
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up_switch_time[1] = 0; |
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down_switch_time[0] = 0; |
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down_switch_time[1] = 0; |
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| 69 | 107 |
attachInterrupt(THR_RECEIVER_INT, receiver_on_thr_interrupt, CHANGE); |
| 70 | 108 |
attachInterrupt(AIL_RECEIVER_INT, receiver_on_ail_interrupt, CHANGE); |
| 71 | 109 |
} |
| ... | ... | |
| 76 | 114 |
// TODO measure throttle positions. |
| 77 | 115 |
int receiver_get_angle(int index) {
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| 78 | 116 |
// Math to convert nThrottleIn to 0-180. |
| 79 |
int ret_val = (rc_value[index]-AIL_RIGHTMOST)*3/17; |
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int ret_val = (int)(rc_value[index]-AIL_RIGHTMOST)*3/17;
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| 80 | 118 |
rc_available[index] = 0; |
| 81 | 119 |
return ret_val; |
| 82 | 120 |
} |
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