src/main/rx/sbus.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 #include <string.h>
  22
  23 #include "platform.h"
  24
  25 #ifdef USE_SERIAL_RX
  26
  27 #include "build/debug.h"
  28
  29 #include "common/utils.h"
  30
  31 #include "drivers/time.h"
  32
  33 #include "io/serial.h"
  34
  35 #ifdef USE_TELEMETRY
  36 #include "telemetry/telemetry.h"
  37 #endif
  38
  39 #include "rx/rx.h"
  40 #include "rx/sbus.h"
  41 #include "rx/sbus_channels.h"
  42
  43 /*
  44  * Observations
  45  *
  46  * FrSky X8R
  47  * time between frames: 6ms.
  48  * time to send frame: 3ms.
  49 *
  50  * Futaba R6208SB/R6303SB
  51  * time between frames: 11ms.
  52  * time to send frame: 3ms.
  53  */
  54 typedef enum {
  55     STATE_SBUS_SYNC = 0,
  56     STATE_SBUS_PAYLOAD,
  57     STATE_SBUS26_PAYLOAD_LOW,
  58     STATE_SBUS26_PAYLOAD_HIGH,
  59     STATE_SBUS_WAIT_SYNC
  60 } sbusDecoderState_e;
  61
  62 typedef struct sbusFrameData_s {
  63     sbusDecoderState_e state;
  64     volatile sbusFrame_t frame;
  65     volatile bool frameDone;
  66     volatile bool is26channels;
  67     uint8_t buffer[SBUS_FRAME_SIZE];
  68     uint8_t position;
  69     timeUs_t lastActivityTimeUs;
  70 } sbusFrameData_t;
  71
  72 static uint8_t sbus2ActiveTelemetryPage = 0;
  73 static uint8_t sbus2ActiveTelemetrySlot = 0;
  74 timeUs_t frameTime = 0;
  75
  76 // Receive ISR callback
  77 static void sbusDataReceive(uint16_t c, void *data)
  78 {
  79     sbusFrameData_t *sbusFrameData = data;
  80     const timeUs_t currentTimeUs = micros();
  81     const timeDelta_t timeSinceLastByteUs = cmpTimeUs(currentTimeUs, sbusFrameData->lastActivityTimeUs);
  82     sbusFrameData->lastActivityTimeUs = currentTimeUs;
  83
  84     // Handle inter-frame gap. We dwell in STATE_SBUS_WAIT_SYNC state ignoring all incoming bytes until we get long enough quite period on the wire
  85     if (sbusFrameData->state == STATE_SBUS_WAIT_SYNC && timeSinceLastByteUs >= rxConfig()->sbusSyncInterval) {
  86         sbusFrameData->state = STATE_SBUS_SYNC;
  87     }
  88
  89     switch (sbusFrameData->state) {
  90         case STATE_SBUS_SYNC:
  91             if (c == SBUS_FRAME_BEGIN_BYTE) {
  92                 sbusFrameData->position = 0;
  93                 sbusFrameData->buffer[sbusFrameData->position++] = (uint8_t)c;
  94                 sbusFrameData->state = STATE_SBUS_PAYLOAD;
  95             } else if (c == SBUS26_FRAME0_BEGIN_BYTE) {
  96                 sbusFrameData->position = 0;
  97                 sbusFrameData->buffer[sbusFrameData->position++] = (uint8_t)c;
  98                 sbusFrameData->state = STATE_SBUS26_PAYLOAD_LOW;
  99             } else if (c == SBUS26_FRAME1_BEGIN_BYTE) {
 100                 sbusFrameData->position = 0;
 101                 sbusFrameData->buffer[sbusFrameData->position++] = (uint8_t)c;
 102                 sbusFrameData->state = STATE_SBUS26_PAYLOAD_HIGH;
 103             }
 104             break;
 105
 106         case STATE_SBUS_PAYLOAD:
 107             sbusFrameData->buffer[sbusFrameData->position++] = (uint8_t)c;
 108
 109             if (sbusFrameData->position == SBUS_FRAME_SIZE) {
 110                 const sbusFrame_t * frame = (sbusFrame_t *)&sbusFrameData->buffer[0];
 111                 bool frameValid = false;
 112
 113                 // Do some sanity check
 114                 switch (frame->endByte) {
 115                     case 0x00:  // This is S.BUS 1
 116                     case 0x04:  // S.BUS 2 telemetry page 1
 117                     case 0x14:  // S.BUS 2 telemetry page 2
 118                     case 0x24:  // S.BUS 2 telemetry page 3
 119                     case 0x34:  // S.BUS 2 telemetry page 4
 120                         if(frame->endByte & 0x4) {
 121                             sbus2ActiveTelemetryPage = (frame->endByte >> 4) & 0xF;
 122                             frameTime = currentTimeUs;
 123                         } else {
 124                             sbus2ActiveTelemetryPage = 0;
 125                             sbus2ActiveTelemetrySlot = 0;
 126                             frameTime = -1;
 127                         }
 128
 129
 130                         frameValid = true;
 131                         sbusFrameData->state = STATE_SBUS_WAIT_SYNC;
 132                         break;
 133
 134                     default:    // Failed end marker
 135                         sbusFrameData->state = STATE_SBUS_WAIT_SYNC;
 136                         break;
 137                 }
 138
 139                 // Frame seems sane, pass data to decoder
 140                 if (!sbusFrameData->frameDone && frameValid) {
 141
 142                     memcpy((void *)&sbusFrameData->frame, (void *)&sbusFrameData->buffer[0], SBUS_FRAME_SIZE);
 143                     sbusFrameData->frameDone = true;
 144                     sbusFrameData->is26channels = false;
 145                 }
 146             }
 147             break;
 148
 149         case STATE_SBUS26_PAYLOAD_LOW:
 150         case STATE_SBUS26_PAYLOAD_HIGH:
 151             sbusFrameData->buffer[sbusFrameData->position++] = (uint8_t)c;
 152
 153             if (sbusFrameData->position == SBUS_FRAME_SIZE) {
 154                 const sbusFrame_t * frame = (sbusFrame_t *)&sbusFrameData->buffer[0];
 155                 bool frameValid = false;
 156
 157                 // Do some sanity check
 158                 switch (frame->endByte) {
 159                     case 0x20:  // S.BUS 2 telemetry page 1
 160                     case 0x24:  // S.BUS 2 telemetry page 2
 161                     case 0x28:  // S.BUS 2 telemetry page 3
 162                     case 0x2C:  // S.BUS 2 telemetry page 4
 163                         if (frame->syncByte == SBUS26_FRAME1_BEGIN_BYTE) {
 164                             sbus2ActiveTelemetryPage = (frame->endByte >> 2) & 0x3;
 165                             frameTime = currentTimeUs;
 166                         }
 167
 168                         frameValid = true;
 169                         sbusFrameData->state = STATE_SBUS_WAIT_SYNC;
 170                         break;
 171
 172                     default:    // Failed end marker
 173                         sbusFrameData->state = STATE_SBUS_WAIT_SYNC;
 174                         break;
 175                 }
 176
 177                 // Frame seems sane, pass data to decoder
 178                 if (!sbusFrameData->frameDone && frameValid) {
 179                     memcpy((void *)&sbusFrameData->frame, (void *)&sbusFrameData->buffer[0], SBUS_FRAME_SIZE);
 180                     sbusFrameData->frameDone = true;
 181                     sbusFrameData->is26channels = true;
 182                 }
 183             }
 184             break;
 185
 186
 187
 188         case STATE_SBUS_WAIT_SYNC:
 189             // Stay at this state and do nothing. Exit will be handled before byte is processed if the
 190             // inter-frame gap is long enough
 191             break;
 192     }
 193 }
 194
 195 static uint8_t sbusFrameStatus(rxRuntimeConfig_t *rxRuntimeConfig)
 196 {
 197     sbusFrameData_t *sbusFrameData = rxRuntimeConfig->frameData;
 198
 199     if (!sbusFrameData->frameDone) {
 200         return RX_FRAME_PENDING;
 201     }
 202
 203     // Decode channel data and store return value
 204     const uint8_t retValue = sbusFrameData->is26channels ?
 205         sbus26ChannelsDecode(rxRuntimeConfig, (void *)&sbusFrameData->frame.channels, (sbusFrameData->frame.syncByte == SBUS26_FRAME1_BEGIN_BYTE)) :
 206         sbusChannelsDecode(rxRuntimeConfig, (void *)&sbusFrameData->frame.channels);
 207
 208     // Reset the frameDone flag - tell ISR that we're ready to receive next frame
 209     sbusFrameData->frameDone = false;
 210
 211     //taskSendSbus2Telemetry(micros());
 212
 213     // Calculate "virtual link quality based on packet loss metric"
 214     if (retValue & RX_FRAME_COMPLETE) {
 215         lqTrackerAccumulate(rxRuntimeConfig->lqTracker, ((retValue & RX_FRAME_DROPPED) || (retValue & RX_FRAME_FAILSAFE)) ? 0 : RSSI_MAX_VALUE);
 216     }
 217
 218     return retValue;
 219 }
 220
 221 static bool sbusInitEx(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig, uint32_t sbusBaudRate)
 222 {
 223     static uint16_t sbusChannelData[SBUS_MAX_CHANNEL];
 224     static sbusFrameData_t sbusFrameData;
 225
 226     rxRuntimeConfig->channelData = sbusChannelData;
 227     rxRuntimeConfig->frameData = &sbusFrameData;
 228
 229     sbusChannelsInit(rxRuntimeConfig);
 230
 231     rxRuntimeConfig->channelCount = SBUS_MAX_CHANNEL;
 232
 233     rxRuntimeConfig->rcFrameStatusFn = sbusFrameStatus;
 234
 235     const serialPortConfig_t *portConfig = findSerialPortConfig(FUNCTION_RX_SERIAL);
 236     if (!portConfig) {
 237         return false;
 238     }
 239
 240 #ifdef USE_TELEMETRY
 241     bool portShared = telemetryCheckRxPortShared(portConfig);
 242 #else
 243     bool portShared = false;
 244 #endif
 245
 246     serialPort_t *sBusPort = openSerialPort(portConfig->identifier,
 247         FUNCTION_RX_SERIAL,
 248         sbusDataReceive,
 249         &sbusFrameData,
 250         sbusBaudRate,
 251         (portShared || rxConfig->serialrx_provider == SERIALRX_SBUS2) ? MODE_RXTX : MODE_RX,
 252         SBUS_PORT_OPTIONS |
 253             (rxConfig->serialrx_inverted ? 0 : SERIAL_INVERTED) |
 254             ((rxConfig->serialrx_provider == SERIALRX_SBUS2) ? SERIAL_BIDIR : 0) |
 255             (tristateWithDefaultOffIsActive(rxConfig->halfDuplex) ? SERIAL_BIDIR : 0)
 256         );
 257
 258 #ifdef USE_TELEMETRY
 259     if (portShared || (rxConfig->serialrx_provider == SERIALRX_SBUS2)) {
 260         telemetrySharedPort = sBusPort;
 261     }
 262 #endif
 263
 264     return sBusPort != NULL;
 265 }
 266
 267 bool sbusInit(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig)
 268 {
 269     return sbusInitEx(rxConfig, rxRuntimeConfig, SBUS_BAUDRATE);
 270 }
 271
 272 bool sbusInitFast(const rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig)
 273 {
 274     return sbusInitEx(rxConfig, rxRuntimeConfig, SBUS_BAUDRATE_FAST);
 275 }
 276
 277 #if defined(USE_TELEMETRY) && defined(USE_TELEMETRY_SBUS2)
 278 timeUs_t sbusGetLastFrameTime(void) {
 279     return frameTime;
 280 }
 281
 282 uint8_t sbusGetCurrentTelemetryNextSlot(void)
 283 {
 284     uint8_t current = sbus2ActiveTelemetrySlot;
 285     sbus2ActiveTelemetrySlot++;
 286     return current;
 287 }
 288
 289 uint8_t sbusGetCurrentTelemetryPage(void) {
 290     return sbus2ActiveTelemetryPage;
 291 }
 292 #endif // USE_TELEMETRY && USE_SBUS2_TELEMETRY
 293
 294 #endif // USE_SERIAL_RX