src/main/rx/ibus.c

   1 /*
   2  * This file is part of Cleanflight and Betaflight.
   3  *
   4  * Cleanflight and Betaflight are free software. You can redistribute
   5  * this software and/or modify this software under the terms of the
   6  * GNU General Public License as published by the Free Software
   7  * Foundation, either version 3 of the License, or (at your option)
   8  * any later version.
   9  *
  10  * Cleanflight and Betaflight are distributed in the hope that they
  11  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  12  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  13  * See the GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this software.
  17  *
  18  * If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 /*
  22  * Driver for IBUS (Flysky) receiver
  23  *   - initial implementation for MultiWii by Cesco/Pl¸schi
  24  *   - implementation for BaseFlight by Andreas (fiendie) Tacke
  25  *   - ported to CleanFlight by Konstantin (digitalentity) Sharlaimov
  26  */
  27
  28 #include <stdbool.h>
  29 #include <stdint.h>
  30 #include <stdlib.h>
  31
  32 #include "platform.h"
  33
  34 #ifdef USE_SERIALRX_IBUS
  35
  36 #include "pg/rx.h"
  37
  38 #include "common/utils.h"
  39
  40 #include "drivers/serial.h"
  41 #include "drivers/serial_uart.h"
  42 #include "drivers/time.h"
  43
  44 #include "io/serial.h"
  45
  46 #ifdef USE_TELEMETRY
  47 #include "telemetry/telemetry.h"
  48 #endif
  49
  50 #include "rx/rx.h"
  51 #include "rx/ibus.h"
  52 #include "telemetry/ibus.h"
  53 #include "telemetry/ibus_shared.h"
  54
  55 #define IBUS_MAX_CHANNEL 18
  56 //In AFHDS there is 18 channels encoded in 14 slots (each slot is 2 byte long)
  57 #define IBUS_MAX_SLOTS 14
  58 #define IBUS_BUFFSIZE 32
  59 #define IBUS_MODEL_IA6B 0
  60 #define IBUS_MODEL_IA6 1
  61 #define IBUS_FRAME_GAP 500
  62
  63 #define IBUS_BAUDRATE 115200
  64 #define IBUS_TELEMETRY_PACKET_LENGTH (4)
  65 #define IBUS_SERIAL_RX_PACKET_LENGTH (32)
  66
  67 static uint8_t ibusModel;
  68 static uint8_t ibusSyncByte;
  69 static uint8_t ibusFrameSize;
  70 static uint8_t ibusChannelOffset;
  71 static uint8_t rxBytesToIgnore;
  72 static uint16_t ibusChecksum;
  73
  74 static bool ibusFrameDone = false;
  75 static uint32_t ibusChannelData[IBUS_MAX_CHANNEL];
  76
  77 static uint8_t ibus[IBUS_BUFFSIZE] = { 0, };
  78 static timeUs_t lastRcFrameTimeUs = 0;
  79
  80 static bool isValidIa6bIbusPacketLength(uint8_t length)
  81 {
  82     return (length == IBUS_TELEMETRY_PACKET_LENGTH) || (length == IBUS_SERIAL_RX_PACKET_LENGTH);
  83 }
  84
  85
  86 // Receive ISR callback
  87 static void ibusDataReceive(uint16_t c, void *data)
  88 {
  89     UNUSED(data);
  90
  91     static timeUs_t ibusTimeLast;
  92     static uint8_t ibusFramePosition;
  93
  94     const timeUs_t ibusTime = microsISR();
  95
  96     if (cmpTimeUs(ibusTime, ibusTimeLast) > IBUS_FRAME_GAP) {
  97         ibusFramePosition = 0;
  98         rxBytesToIgnore = 0;
  99     } else if (rxBytesToIgnore) {
 100         rxBytesToIgnore--;
 101         return;
 102     }
 103
 104     ibusTimeLast = ibusTime;
 105
 106     if (ibusFramePosition == 0) {
 107         if (isValidIa6bIbusPacketLength(c)) {
 108             ibusModel = IBUS_MODEL_IA6B;
 109             ibusSyncByte = c;
 110             ibusFrameSize = c;
 111             ibusChannelOffset = 2;
 112             ibusChecksum = 0xFFFF;
 113         } else if ((ibusSyncByte == 0) && (c == 0x55)) {
 114             ibusModel = IBUS_MODEL_IA6;
 115             ibusSyncByte = 0x55;
 116             ibusFrameSize = 31;
 117             ibusChecksum = 0x0000;
 118             ibusChannelOffset = 1;
 119         } else if (ibusSyncByte != c) {
 120             return;
 121         }
 122     }
 123
 124     ibus[ibusFramePosition] = (uint8_t)c;
 125
 126     if (ibusFramePosition == ibusFrameSize - 1) {
 127         lastRcFrameTimeUs = ibusTime;
 128         ibusFrameDone = true;
 129     } else {
 130         ibusFramePosition++;
 131     }
 132 }
 133
 134
 135 static bool isChecksumOkIa6(void)
 136 {
 137     uint8_t offset;
 138     uint8_t i;
 139     uint16_t chksum, rxsum;
 140     chksum = ibusChecksum;
 141     rxsum = ibus[ibusFrameSize - 2] + (ibus[ibusFrameSize - 1] << 8);
 142     for (i = 0, offset = ibusChannelOffset; i < IBUS_MAX_SLOTS; i++, offset += 2) {
 143         chksum += ibus[offset] + (ibus[offset + 1] << 8);
 144     }
 145     return chksum == rxsum;
 146 }
 147
 148
 149 static bool checksumIsOk(void) {
 150     if (ibusModel == IBUS_MODEL_IA6 ) {
 151         return isChecksumOkIa6();
 152     } else {
 153         return isChecksumOkIa6b(ibus, ibusFrameSize);
 154     }
 155 }
 156
 157
 158 static void updateChannelData(void) {
 159     uint8_t i;
 160     uint8_t offset;
 161     for (i = 0, offset = ibusChannelOffset; i < IBUS_MAX_SLOTS; i++, offset += 2) {
 162         ibusChannelData[i] = ibus[offset] + ((ibus[offset + 1] & 0x0F) << 8);
 163     }
 164     //latest IBUS recievers are using prviously not used 4 bits on every channel to incresse total channel count
 165     for (i = IBUS_MAX_SLOTS, offset = ibusChannelOffset + 1; i < IBUS_MAX_CHANNEL; i++, offset += 6) {
 166         ibusChannelData[i] = ((ibus[offset] & 0xF0) >> 4) | (ibus[offset + 2] & 0xF0) | ((ibus[offset + 4] & 0xF0) << 4);
 167     }
 168 }
 169
 170 static uint8_t ibusFrameStatus(rxRuntimeState_t *rxRuntimeState)
 171 {
 172     UNUSED(rxRuntimeState);
 173
 174     uint8_t frameStatus = RX_FRAME_PENDING;
 175
 176     if (!ibusFrameDone) {
 177         return frameStatus;
 178     }
 179
 180     ibusFrameDone = false;
 181
 182     if (checksumIsOk()) {
 183         if (ibusModel == IBUS_MODEL_IA6 || ibusSyncByte == IBUS_SERIAL_RX_PACKET_LENGTH) {
 184             updateChannelData();
 185             frameStatus = RX_FRAME_COMPLETE;
 186         }
 187         else
 188         {
 189 #if defined(USE_TELEMETRY) && defined(USE_TELEMETRY_IBUS)
 190             rxBytesToIgnore = respondToIbusRequest(ibus);
 191 #endif
 192         }
 193     }
 194
 195     if (frameStatus != RX_FRAME_COMPLETE) {
 196         lastRcFrameTimeUs = 0;  // We received a frame but it wasn't valid new channel data
 197     }
 198
 199     return frameStatus;
 200 }
 201
 202
 203 static uint16_t ibusReadRawRC(const rxRuntimeState_t *rxRuntimeState, uint8_t chan)
 204 {
 205     UNUSED(rxRuntimeState);
 206     return ibusChannelData[chan];
 207 }
 208
 209 static timeUs_t ibusFrameTimeUs(void)
 210 {
 211     const timeUs_t result = lastRcFrameTimeUs;
 212     lastRcFrameTimeUs = 0;
 213     return result;
 214 }
 215
 216 bool ibusInit(const rxConfig_t *rxConfig, rxRuntimeState_t *rxRuntimeState)
 217 {
 218     UNUSED(rxConfig);
 219     ibusSyncByte = 0;
 220
 221     rxRuntimeState->channelCount = IBUS_MAX_CHANNEL;
 222     rxRuntimeState->rxRefreshRate = 20000; // TODO - Verify speed
 223
 224     rxRuntimeState->rcReadRawFn = ibusReadRawRC;
 225     rxRuntimeState->rcFrameStatusFn = ibusFrameStatus;
 226     rxRuntimeState->rcFrameTimeUsFn = ibusFrameTimeUs;
 227
 228     const serialPortConfig_t *portConfig = findSerialPortConfig(FUNCTION_RX_SERIAL);
 229     if (!portConfig) {
 230         return false;
 231     }
 232
 233 #ifdef USE_TELEMETRY
 234     bool portShared = isSerialPortShared(portConfig, FUNCTION_RX_SERIAL, FUNCTION_TELEMETRY_IBUS);
 235 #else
 236     bool portShared = false;
 237 #endif
 238
 239
 240     rxBytesToIgnore = 0;
 241     serialPort_t *ibusPort = openSerialPort(portConfig->identifier,
 242         FUNCTION_RX_SERIAL,
 243         ibusDataReceive,
 244         NULL,
 245         IBUS_BAUDRATE,
 246         portShared ? MODE_RXTX : MODE_RX,
 247         (rxConfig->serialrx_inverted ? SERIAL_INVERTED : 0) | (rxConfig->halfDuplex || portShared ? SERIAL_BIDIR : 0)
 248         );
 249
 250 #if defined(USE_TELEMETRY) && defined(USE_TELEMETRY_IBUS)
 251     if (portShared) {
 252         initSharedIbusTelemetry(ibusPort);
 253     }
 254 #endif
 255
 256     return ibusPort != NULL;
 257 }
 258
 259 #endif //SERIAL_RX