src/main/io/transponder_ir.c

   1 /*
   2  * This file is part of Cleanflight.
   3  *
   4  * Cleanflight is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * Cleanflight is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <stdbool.h>
  19 #include <stdlib.h>
  20 #include <stdint.h>
  21 #include <string.h>
  22 #include <stdarg.h>
  23
  24 #include <platform.h>
  25
  26 #include <build_config.h>
  27
  28 #include "drivers/transponder_ir.h"
  29 #include "drivers/system.h"
  30
  31 #include "drivers/usb_detection.h"
  32
  33 #include "io/transponder_ir.h"
  34 #include "config/config.h"
  35
  36 static bool transponderInitialised = false;
  37 static bool transponderRepeat = false;
  38
  39 // timers
  40 static uint32_t nextUpdateAt = 0;
  41
  42 #define JITTER_DURATION_COUNT (sizeof(jitterDurations) / sizeof(uint8_t))
  43 static uint8_t jitterDurations[] = {0,9,4,8,3,9,6,7,1,6,9,7,8,2,6};
  44
  45 void updateTransponder(void)
  46 {
  47     static uint32_t jitterIndex = 0;
  48
  49     if (!(transponderInitialised && transponderRepeat && isTransponderIrReady())) {
  50         return;
  51     }
  52
  53     uint32_t now = micros();
  54
  55     bool updateNow = (int32_t)(now - nextUpdateAt) >= 0L;
  56     if (!updateNow) {
  57         return;
  58     }
  59
  60     // TODO use a random number genenerator for random jitter?  The idea here is to avoid multiple transmitters transmitting at the same time.
  61     uint32_t jitter = (1000 * jitterDurations[jitterIndex++]);
  62     if (jitterIndex >= JITTER_DURATION_COUNT) {
  63         jitterIndex = 0;
  64     }
  65
  66     nextUpdateAt = now + 4500 + jitter;
  67
  68 #ifdef SPRACINGF3MINI
  69     // reduce current draw when USB cable is plugged in by decreasing the transponder transmit rate.
  70     if (usbCableIsInserted()) {
  71         nextUpdateAt = now + (1000 * 1000) / 10; // 10 hz.
  72     }
  73 #endif
  74
  75     transponderIrTransmit();
  76 }
  77
  78 void transponderInit(uint8_t* transponderData)
  79 {
  80     transponderInitialised = false;
  81     transponderIrInit();
  82     transponderIrUpdateData(transponderData);
  83 }
  84
  85 void transponderEnable(void)
  86 {
  87     transponderInitialised = true;
  88 }
  89
  90 void transponderDisable(void)
  91 {
  92     transponderInitialised = false;
  93 }
  94
  95 void transponderStopRepeating(void)
  96 {
  97     transponderRepeat = false;
  98 }
  99
 100 void transponderStartRepeating(void)
 101 {
 102     transponderRepeat = true;
 103 }
 104
 105 void transponderUpdateData(uint8_t* transponderData)
 106 {
 107     transponderIrUpdateData(transponderData);
 108 }
 109
 110 void transponderTransmitOnce(void) {
 111
 112     if (!transponderInitialised) {
 113         return;
 114     }
 115     transponderIrTransmit();
 116 }