src/main/rx/sbus_channels.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 <stdint.h>
  20 #include <stdlib.h>
  21
  22 #include "platform.h"
  23
  24 #ifdef USE_SERIAL_RX
  25
  26 #include "common/utils.h"
  27 #include "common/maths.h"
  28
  29 #include "rx/sbus_channels.h"
  30
  31
  32 #define SBUS_DIGITAL_CHANNEL_MIN 173
  33 #define SBUS_DIGITAL_CHANNEL_MAX 1812
  34
  35 STATIC_ASSERT(SBUS_FRAME_SIZE == sizeof(sbusFrame_t), SBUS_FRAME_SIZE_doesnt_match_sbusFrame_t);
  36
  37 uint8_t sbus26ChannelsDecode(rxRuntimeConfig_t *rxRuntimeConfig, const sbusChannels_t *channels, bool highChannels)
  38 {
  39     uint8_t offset = highChannels ? 16 : 0
  40     uint16_t *sbusChannelData = rxRuntimeConfig->channelData;
  41     sbusChannelData[0 + offset] = channels->chan0;
  42     sbusChannelData[1 + offset] = channels->chan1;
  43     sbusChannelData[2 + offset] = channels->chan2;
  44     sbusChannelData[3 + offset] = channels->chan3;
  45     sbusChannelData[4 + offset] = channels->chan4;
  46     sbusChannelData[5 + offset] = channels->chan5;
  47     sbusChannelData[6 + offset] = channels->chan6;
  48     sbusChannelData[7 + offset] = channels->chan7;
  49     sbusChannelData[8 + offset] = channels->chan8;
  50     sbusChannelData[9 + offset] = channels->chan9;
  51     sbusChannelData[10 + offset] = channels->chan10;
  52     sbusChannelData[11 + offset] = channels->chan11;
  53     sbusChannelData[12 + offset] = channels->chan12;
  54     sbusChannelData[13 + offset] = channels->chan13;
  55     sbusChannelData[14 + offset] = channels->chan14;
  56     sbusChannelData[15 + offset] = channels->chan15;
  57
  58     offset = highChannels ? 0 : 2;
  59     if (channels->flags & SBUS_FLAG_CHANNEL_DG1) {
  60         sbusChannelData[32 + offset] = SBUS_DIGITAL_CHANNEL_MAX;
  61     } else {
  62         sbusChannelData[32 + offset] = SBUS_DIGITAL_CHANNEL_MIN;
  63     }
  64
  65     if (channels->flags & SBUS_FLAG_CHANNEL_DG2) {
  66         sbusChannelData[33 + offset] = SBUS_DIGITAL_CHANNEL_MAX;
  67     } else {
  68         sbusChannelData[33 + offset] = SBUS_DIGITAL_CHANNEL_MIN;
  69     }
  70
  71     if (channels->flags & SBUS_FLAG_FAILSAFE_ACTIVE) {
  72         // internal failsafe enabled and rx failsafe flag set
  73         // RX *should* still be sending valid channel data, so use it.
  74         return RX_FRAME_COMPLETE | RX_FRAME_FAILSAFE;
  75     }
  76
  77     if (channels->flags & SBUS_FLAG_SIGNAL_LOSS) {
  78         // The received data is a repeat of the last valid data so can be considered complete.
  79         return RX_FRAME_COMPLETE | RX_FRAME_DROPPED;
  80     }
  81
  82     return RX_FRAME_COMPLETE;
  83 }
  84
  85 uint8_t sbusChannelsDecode(rxRuntimeConfig_t *rxRuntimeConfig, const sbusChannels_t *channels)
  86 {
  87     uint16_t *sbusChannelData = rxRuntimeConfig->channelData;
  88     sbusChannelData[0] = channels->chan0;
  89     sbusChannelData[1] = channels->chan1;
  90     sbusChannelData[2] = channels->chan2;
  91     sbusChannelData[3] = channels->chan3;
  92     sbusChannelData[4] = channels->chan4;
  93     sbusChannelData[5] = channels->chan5;
  94     sbusChannelData[6] = channels->chan6;
  95     sbusChannelData[7] = channels->chan7;
  96     sbusChannelData[8] = channels->chan8;
  97     sbusChannelData[9] = channels->chan9;
  98     sbusChannelData[10] = channels->chan10;
  99     sbusChannelData[11] = channels->chan11;
 100     sbusChannelData[12] = channels->chan12;
 101     sbusChannelData[13] = channels->chan13;
 102     sbusChannelData[14] = channels->chan14;
 103     sbusChannelData[15] = channels->chan15;
 104
 105     if (channels->flags & SBUS_FLAG_CHANNEL_DG1) {
 106         sbusChannelData[16] = SBUS_DIGITAL_CHANNEL_MAX;
 107     } else {
 108         sbusChannelData[16] = SBUS_DIGITAL_CHANNEL_MIN;
 109     }
 110
 111     if (channels->flags & SBUS_FLAG_CHANNEL_DG2) {
 112         sbusChannelData[17] = SBUS_DIGITAL_CHANNEL_MAX;
 113     } else {
 114         sbusChannelData[17] = SBUS_DIGITAL_CHANNEL_MIN;
 115     }
 116
 117     if (channels->flags & SBUS_FLAG_FAILSAFE_ACTIVE) {
 118         // internal failsafe enabled and rx failsafe flag set
 119         // RX *should* still be sending valid channel data, so use it.
 120         return RX_FRAME_COMPLETE | RX_FRAME_FAILSAFE;
 121     }
 122
 123     if (channels->flags & SBUS_FLAG_SIGNAL_LOSS) {
 124         // The received data is a repeat of the last valid data so can be considered complete.
 125         return RX_FRAME_COMPLETE | RX_FRAME_DROPPED;
 126     }
 127
 128     return RX_FRAME_COMPLETE;
 129 }
 130
 131 uint16_t sbusDecodeChannelValue(uint16_t sbusValue, bool safeValuesOnly)
 132 {
 133     // Linear fitting values read from OpenTX-ppmus and comparing with values received by X4R
 134     // http://www.wolframalpha.com/input/?i=linear+fit+%7B173%2C+988%7D%2C+%7B1812%2C+2012%7D%2C+%7B993%2C+1500%7D
 135     if (safeValuesOnly) {
 136         // Clip channel values to more or less safe values (988 .. 2012)
 137         return (5 * constrain(sbusValue, SBUS_DIGITAL_CHANNEL_MIN, SBUS_DIGITAL_CHANNEL_MAX) / 8) + 880;
 138     }
 139     else {
 140         // Use full range of values (11 bit, channel values in range 880 .. 2159)
 141         return (5 * constrain(sbusValue, 0, 2047) / 8) + 880;
 142     }
 143 }
 144
 145 uint16_t sbusEncodeChannelValue(uint16_t rcValue)
 146 {
 147     return constrain((((int)rcValue - 880) * 8 + 4) / 5, SBUS_DIGITAL_CHANNEL_MIN, SBUS_DIGITAL_CHANNEL_MAX);
 148 }
 149
 150 static uint16_t sbusChannelsReadRawRC(const rxRuntimeConfig_t *rxRuntimeConfig, uint8_t chan)
 151 {
 152     return sbusDecodeChannelValue(rxRuntimeConfig->channelData[chan], false);
 153 }
 154
 155 void sbusChannelsInit(rxRuntimeConfig_t *rxRuntimeConfig)
 156 {
 157     rxRuntimeConfig->rcReadRawFn = sbusChannelsReadRawRC;
 158     for (int b = 0; b < SBUS_MAX_CHANNEL; b++) {
 159         rxRuntimeConfig->channelData[b] = (16 * PWM_RANGE_MIDDLE) / 10 - 1408;
 160     }
 161 }
 162 #endif