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 lastFrameTimeUs = 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 // Receive ISR callback
  86 static void ibusDataReceive(uint16_t c, void *data)
  87 {
  88     UNUSED(data);
  89
  90     static timeUs_t ibusTimeLast;
  91     static uint8_t ibusFramePosition;
  92
  93     const timeUs_t now = microsISR();
  94
  95     if (cmpTimeUs(now, ibusTimeLast) > IBUS_FRAME_GAP) {
  96         ibusFramePosition = 0;
  97         rxBytesToIgnore = 0;
  98     } else if (rxBytesToIgnore) {
  99         rxBytesToIgnore--;
 100         return;
 101     }
 102
 103     ibusTimeLast = now;
 104
 105     if (ibusFramePosition == 0) {
 106         if (isValidIa6bIbusPacketLength(c)) {
 107             ibusModel = IBUS_MODEL_IA6B;
 108             ibusSyncByte = c;
 109             ibusFrameSize = c;
 110             ibusChannelOffset = 2;
 111             ibusChecksum = 0xFFFF;
 112         } else if ((ibusSyncByte == 0) && (c == 0x55)) {
 113             ibusModel = IBUS_MODEL_IA6;
 114             ibusSyncByte = 0x55;
 115             ibusFrameSize = 31;
 116             ibusChecksum = 0x0000;
 117             ibusChannelOffset = 1;
 118         } else if (ibusSyncByte != c) {
 119             return;
 120         }
 121     }
 122
 123     ibus[ibusFramePosition] = (uint8_t)c;
 124
 125     if (ibusFramePosition == ibusFrameSize - 1) {
 126         lastFrameTimeUs = now;
 127         ibusFrameDone = true;
 128     } else {
 129         ibusFramePosition++;
 130     }
 131 }
 132
 133 static bool isChecksumOkIa6(void)
 134 {
 135     uint8_t offset;
 136     uint8_t i;
 137     uint16_t chksum, rxsum;
 138     chksum = ibusChecksum;
 139     rxsum = ibus[ibusFrameSize - 2] + (ibus[ibusFrameSize - 1] << 8);
 140     for (i = 0, offset = ibusChannelOffset; i < IBUS_MAX_SLOTS; i++, offset += 2) {
 141         chksum += ibus[offset] + (ibus[offset + 1] << 8);
 142     }
 143     return chksum == rxsum;
 144 }
 145
 146 static bool checksumIsOk(void)
 147 {
 148     if (ibusModel == IBUS_MODEL_IA6 ) {
 149         return isChecksumOkIa6();
 150     } else {
 151         return isChecksumOkIa6b(ibus, ibusFrameSize);
 152     }
 153 }
 154
 155 static void updateChannelData(void)
 156 {
 157     uint8_t i;
 158     uint8_t offset;
 159     for (i = 0, offset = ibusChannelOffset; i < IBUS_MAX_SLOTS; i++, offset += 2) {
 160         ibusChannelData[i] = ibus[offset] + ((ibus[offset + 1] & 0x0F) << 8);
 161     }
 162     //latest IBUS recievers are using prviously not used 4 bits on every channel to incresse total channel count
 163     for (i = IBUS_MAX_SLOTS, offset = ibusChannelOffset + 1; i < IBUS_MAX_CHANNEL; i++, offset += 6) {
 164         ibusChannelData[i] = ((ibus[offset] & 0xF0) >> 4) | (ibus[offset + 2] & 0xF0) | ((ibus[offset + 4] & 0xF0) << 4);
 165     }
 166 }
 167
 168 static uint8_t ibusFrameStatus(rxRuntimeState_t *rxRuntimeState)
 169 {
 170     UNUSED(rxRuntimeState);
 171
 172     uint8_t frameStatus = RX_FRAME_PENDING;
 173
 174     if (!ibusFrameDone) {
 175         return frameStatus;
 176     }
 177
 178     ibusFrameDone = false;
 179
 180     if (checksumIsOk()) {
 181         if (ibusModel == IBUS_MODEL_IA6 || ibusSyncByte == IBUS_SERIAL_RX_PACKET_LENGTH) {
 182             updateChannelData();
 183             frameStatus = RX_FRAME_COMPLETE;
 184             rxRuntimeState->lastRcFrameTimeUs = lastFrameTimeUs;
 185 #if defined(USE_TELEMETRY) && defined(USE_TELEMETRY_IBUS)
 186         } else {
 187             rxBytesToIgnore = respondToIbusRequest(ibus);
 188 #endif
 189         }
 190     }
 191
 192     return frameStatus;
 193 }
 194
 195 static float ibusReadRawRC(const rxRuntimeState_t *rxRuntimeState, uint8_t chan)
 196 {
 197     UNUSED(rxRuntimeState);
 198     return ibusChannelData[chan];
 199 }
 200
 201 bool ibusInit(const rxConfig_t *rxConfig, rxRuntimeState_t *rxRuntimeState)
 202 {
 203     UNUSED(rxConfig);
 204     ibusSyncByte = 0;
 205
 206     rxRuntimeState->channelCount = IBUS_MAX_CHANNEL;
 207     rxRuntimeState->rcReadRawFn = ibusReadRawRC;
 208     rxRuntimeState->rcFrameStatusFn = ibusFrameStatus;
 209
 210     const serialPortConfig_t *portConfig = findSerialPortConfig(FUNCTION_RX_SERIAL);
 211     if (!portConfig) {
 212         return false;
 213     }
 214
 215 #ifdef USE_TELEMETRY
 216     bool portShared = isSerialPortShared(portConfig, FUNCTION_RX_SERIAL, FUNCTION_TELEMETRY_IBUS);
 217 #else
 218     bool portShared = false;
 219 #endif
 220
 221     rxBytesToIgnore = 0;
 222     serialPort_t *ibusPort = openSerialPort(portConfig->identifier,
 223         FUNCTION_RX_SERIAL,
 224         ibusDataReceive,
 225         NULL,
 226         IBUS_BAUDRATE,
 227         portShared ? MODE_RXTX : MODE_RX,
 228         (rxConfig->serialrx_inverted ? SERIAL_INVERTED : SERIAL_NOT_INVERTED) | ((rxConfig->halfDuplex || portShared) ? SERIAL_BIDIR : 0)
 229         );
 230
 231 #if defined(USE_TELEMETRY) && defined(USE_TELEMETRY_IBUS)
 232     if (portShared) {
 233         initSharedIbusTelemetry(ibusPort);
 234     }
 235 #endif
 236
 237     return ibusPort != NULL;
 238 }
 239
 240 #endif //SERIAL_RX