AMiRo-OS

/*

AMiRo-OS is an operating system designed for the Autonomous Mini Robot (AMiRo) platform.

Copyright (C) 2016..2019  Thomas Schöpping et al.

This program is free software: you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation, either version 3 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

/**

 * @file    aos_main.cpp

 * @brief   Main function.

 * @details Main function with SSSP and initialization,

 *          extendable via hooks.

 *

 * @addtogroup aos_system

 * @{

 */

#include <amiroos.h>

#include <module.h>

/*

 * hook to add further includes

 */

#if defined(AMIROOS_CFG_MAIN_EXTRA_INCLUDE_HEADER)

#include AMIROOS_CFG_MAIN_EXTRA_INCLUDE_HEADER

#endif

/**

 * @brief   Event mask to identify I/O events.

 */

#define IOEVENT_MASK                            EVENT_MASK(0)

/**

 * @brief   Event mask to identify OS events.

 */

#define OSEVENT_MASK                            EVENT_MASK(1)

/**

 * @brief   Event mask to idetify CAN events.

 */

#define CANEVENT_MASK                           EVENT_MASK(2)

/**

 * @brief   Event mask to idetify timeout events.

 */

#define TIMEOUTEVENT_MASK                       EVENT_MASK(3)

/**

 * @brief   Event mask to idetify signal delay events.

 */

#define DELAYEVENT_MASK                         EVENT_MASK(4)

#if (AMIROOS_CFG_SSSP_ENABLE == true) || defined(__DOXYGEN__)

/**

 * @brief   CAN message identifier for initialization of the SSSP stack initialization sequence.

 */

#define SSSP_STACKINIT_CANMSGID_INIT            0x003

/**

 * @brief   CAN message identifier for transmitting module IDs during the SSSP stack initialization sequence.

 */

#define SSSP_STACKINIT_CANMSGID_MODULEID        0x002

/**

 * @brief   CAN message identifier for abortion of the SSSP stack initialization sequence.

 */

#define SSSP_STACKINIT_CANMSGID_ABORT           0x001

#else /* AMIROOS_CFG_SSSP_ENABLE == false */

/**

 * @brief   Default shutdown mode if SSSP is unavailable.

 */

#define AOS_SHUTDOWN_DEFAULT                    AOS_SHUTDOWN_DEEPSLEEP

#endif /* AMIROOS_CFG_SSSP_ENABLE */

/**

 * @brief   CAN message identifier for calender synchronization message.

 */

#define CALENDERSYNC_CANMSGID                   0x004

/**

 * @brief   Listener object for I/O events.

 */

static event_listener_t _eventListenerIO;

/**

 * @brief   Listener object for OS events.

 */

static event_listener_t _eventListenerOS;

#if defined(MODULE_HAL_PROGIF) || defined(__DOXYGEN__)

/**

 * @brief   I/O channel for the programmer interface.

 */

static AosIOChannel _stdiochannel;

#if (AMIROOS_CFG_SHELL_ENABLE == true) || defined(__DOXYGEN__)

/**

 * @brief   I/O shell channel for the programmer interface.

 */

static AosShellChannel _stdshellchannel;

#endif /* AMIROOS_CFG_SHELL_ENABLE == true */

#endif /* defined(MODULE_HAL_PROGIF) */

/*

 * hook to add further static variables

 */

#if defined(AMIROOS_CFG_MAIN_EXTRA_STATIC_VARIABLES)

AMIROOS_CFG_MAIN_EXTRA_STATIC_VARIABLES

#endif

/**

 * @brief   Prints an error message about an unexpected event.

 *

 * @param[in] mask    The event mask.

 * @param[in] flags   The event flags.

 */

static inline void _unexpectedEventError(const eventmask_t mask, const eventflags_t flags)

{

#if (AMIROOS_CFG_DBG == true)

  aosprintf("CTRL: unexpected/unknown event received. mask: 0x%08X; flags: 0x%08X\n", mask, flags);

#else

  (void)(mask);

  (void)(flags);

#endif

  return;

}

#if (AMIROOS_CFG_SSSP_ENABLE == true) || defined(__DOXYGEN__)

/**

 * @brief   Callback function to be used during SSSP stack initialization sequence.

 *

 * @param[in] par   A pointer to an @p event_source_t to be fired.

 */

static void _ssspTimerCallback(void* par)

{

  aosDbgCheck(par != NULL);

  chSysLockFromISR();

  chEvtBroadcastI((event_source_t*)par);

  chSysUnlockFromISR();

  return;

}

#endif /* AMIROOS_CFG_SSSP_ENABLE == true */

/**

 * @brief   Helper function to serialize data.

 *

 * @param[out]  dst   Pointer to the output buffer.

 * @param[in]   src   Data to be serialized.

 * @param[in]   n     Number of bytes to serialize.

 */

inline void _serialize(uint8_t* dst, const uint64_t src, const uint8_t n)

{

  aosDbgCheck(dst != NULL);

  aosDbgCheck(n > 0 && n <= 8);

  for (uint8_t byte = 0; byte < n; ++byte) {

    dst[byte] = (uint8_t)((src >> (byte * 8)) & 0xFF);

  }

  return;

}

/**

 * @brief   Helper function to deserialize data.

 *

 * @param[in] src   Pointer to the buffer of data to be deserialzed.

 * @param[in] n     Number of bytes to deserialize.

 *

 * @return    The deserialized 32 bit data.

 */

inline uint64_t _deserialize(uint8_t* src, const uint8_t n)

{

  aosDbgCheck(src != NULL);

  aosDbgCheck(n > 0 && n <= 8);

  uint64_t result = 0;

  for (uint8_t byte = 0; byte < n; ++byte) {

    result |= ((uint64_t)src[byte]) << (byte * 8);

  }

  return result;

}

/**

 * @brief   Converter function to encode a TM value to a single unsigned 64 bit integer.

 *

 * @details Contents of the TM struct are mapped as follows:

 *            bits  |63     62|61      53|52    50|49         26|25     22|21     17|16     12|11      6|5       0|

 *            #bits |       2 |        9 |      3 |          24 |       4 |       5 |       5 |       6 |       6 |

 *            value |   isdst |     yday |   wday |        year |     mon |    mday |    hour |     min |     sec |

 *            range | special | [0, 365] | [0, 6] | [1900, ...] | [0, 11] | [1, 31] | [0, 23] | [0, 59] | [0, 61] |

 *          The Daylight Saving Time Flag (isdsst) is encoded as follows:

 *            DST not in effect         -> 0

 *            DST in effect             -> 1

 *            no information available  -> 2

 *

 * @param[in] src   Pointer to the TM struct to encode.

 *

 * @return  An unsigned 64 bit integer, which holds the encoded time value.

 */

inline uint64_t _TM2U64(struct tm* src)

{

  aosDbgCheck(src != NULL);

  return (((uint64_t)(src->tm_sec  & 0x0000003F) << (0))               |

          ((uint64_t)(src->tm_min  & 0x0000003F) << (6))               |

          ((uint64_t)(src->tm_hour & 0x0000001F) << (12))              |

          ((uint64_t)(src->tm_mday & 0x0000001F) << (17))              |

          ((uint64_t)(src->tm_mon  & 0x0000000F) << (22))              |

          ((uint64_t)(src->tm_year & 0x00FFFFFF) << (26))              |

          ((uint64_t)(src->tm_wday & 0x00000007) << (50))              |

          ((uint64_t)(src->tm_yday & 0x000001FF) << (53))              |

          ((uint64_t)((src->tm_isdst == 0) ? 0 : (src->tm_isdst > 0) ? 1 : 2) << (62)));

}

/**

 * @brief   Converter functiomn to retrieve the encoded TM value from an unsigned 64 bit integer.

 *

 * @details For information on the encoding, please refer to @p _TM2U64 function.

 *

 * @param[out] dst  The TM struct to fill with the decoded values.

 * @param[in]  src  Unsigned 64 bit integer holding the encoded TM value.

 */

inline void _U642TM(struct tm* dst, const uint64_t src)

{

  aosDbgCheck(dst != NULL);

  dst->tm_sec  = (src >> 0)  & 0x0000003F;

  dst->tm_min  = (src >> 6)  & 0x0000003F;

  dst->tm_hour = (src >> 12) & 0x0000001F;

  dst->tm_mday = (src >> 17) & 0x0000001F;

  dst->tm_mon  = (src >> 22) & 0x0000000F;

  dst->tm_year = (src >> 26) & 0x00FFFFFF;

  dst->tm_wday = (src >> 50) & 0x00000007;

  dst->tm_yday = (src >> 53) & 0x000001FF;

  dst->tm_isdst = (((src >> 62) & 0x03) == 0) ? 0 : (((src >> 62) & 0x03) > 0) ? 1 : -1;

  return;

}

#if (AMIROOS_CFG_SSSP_ENABLE == true) || defined(__DOXYGEN__)

/**

 * @brief   Implementation of the SSSP module stack initialization sequence (startup phase 3).

 *

 * @return Shutdown value.

 * @retval AOS_SHUTDOWN_NONE      No shutdown signal received

 * @retval AOS_SHUTDOWN_PASSIVE   Shutdown signal received.

 */

aos_shutdown_t _ssspModuleStackInitialization(void)

{

  // local types

  /**

   * @brief   States for the internal state machine to implement SSSP startup stage 3.

   */

  typedef enum {

    STAGE_3_1,                  /**< Initiation of SSSP startup stage 3. */

    STAGE_3_2,                  /**< Starting the sequence and broadcasting the first ID. */

    STAGE_3_3_WAITFORFIRSTID,   /**< Waiting for first ID after initiation. */

    STAGE_3_3_WAITFORIDORSIG,   /**< Waiting for next ID or activation of neighbor signal. */

    STAGE_3_3_WAITFORID,        /**< Waiting for next ID (after the module has set its own ID). */

    STAGE_3_4_FINISH,           /**< Successful finish of stage 3. */

    STAGE_3_4_ABORT_ACTIVE,     /**< Aborting stage 3 (active). */

    STAGE_3_4_ABORT,            /**< Aborting stage 3 (passive). */

  } sssp_modulestackinitstage_t;

  typedef struct {

    bool loop     : 1;

    bool wfe      : 1;

    bool wfe_next : 1;

  } flags_t;

  // local variables

  aos_shutdown_t shutdown = AOS_SHUTDOWN_NONE;

  sssp_modulestackinitstage_t stage = STAGE_3_1;

  eventmask_t eventmask = 0;

  eventflags_t ioflags = 0;

  event_source_t eventSourceTimeout;

  event_source_t eventSourceDelay;

  event_listener_t eventListenerTimeout;

  event_listener_t eventListenerDelay;

  event_listener_t eventListenerCan;

  virtual_timer_t timerTimeout;

  virtual_timer_t timerDelay;

  CANTxFrame canTxFrame;

  CANRxFrame canRxFrame;

#if (AMIROOS_CFG_SSSP_STACK_START != true) || (AMIROOS_CFG_DBG == true)

  aos_ssspmoduleid_t lastid = 0;

#endif

  flags_t flags;

  aos_timestamp_t uptime;

  // initialize local varibles

  chEvtObjectInit(&eventSourceTimeout);

  chEvtObjectInit(&eventSourceDelay);

  chVTObjectInit(&timerTimeout);

  chVTObjectInit(&timerDelay);

  canTxFrame.RTR = CAN_RTR_DATA;

  canTxFrame.IDE = CAN_IDE_STD;

  flags.loop = true;

  flags.wfe = false; // do not wait for events in the initial iteration of the FSM loop

  flags.wfe_next = true;

  // initialize system variables

  aos.sssp.stage = AOS_SSSP_STARTUP_3_1;

  aos.sssp.moduleId = 0;

  // listen to events (timout, delay, CAN receive)

  chEvtRegisterMask(&eventSourceTimeout, &eventListenerTimeout, TIMEOUTEVENT_MASK);

  chEvtRegisterMask(&eventSourceDelay, &eventListenerDelay, DELAYEVENT_MASK);

  chEvtRegisterMask(&MODULE_HAL_CAN.rxfull_event, &eventListenerCan, CANEVENT_MASK);

  /*

   * FSM in a loop.

   *

   * This is a fully event-based FSM for the module stack initialization

   * sequence, defined by SSSP as startup stage 3. There are five different

   * events that can occur at this point:

   *  I/O events: The input level of an input pin has changed. Such events must

   *              be handled differently depending on the current state. Most

   *              of the time, however, such events can be ignored.

   *  OS events:  Such events are only available after this stage completed and

   *              thus should never occur. However, there is an optional hook

   *              to handle such events, nevertheless.

   *  CAN events: At least one CAN message was received. Note that this event

   *              will only fire again if all input buffers have been cleared.

   *  timeouts:   If some module does not support the sequence of there is any

   *              issue, such a case is detected via timeouts and must be

   *              handled accordingly (see abort state). In some cases, it is

   *              possible that a timeout event occurres 'simultaneously' with

   *              some other event. This can be caused by several timing issues

   *              and is a valid situation. As a result, any other events

   *              should be handled before the timeout event. If the other

   *              events are expected and valid, this implementation requires

   *              the timeout event flag to be cleared explicitely. Otherwise

   *              it is evaluated at the end of each iteration of the loop.

   *  delays:     Depending on the current state, delays are required by SSSP

   *              for timing of the sequential activation of signals.

   */

  aosDbgPrintf("SSSP stack initialization sequence:\n");

  while (flags.loop) {

#if (AMIROOS_CFG_DBG == true)

    switch (stage) {

      case STAGE_3_1:

        aosDbgPrintf(">>> 3-1\n");

        break;

      case STAGE_3_2:

        aosDbgPrintf(">>> 3-2\n");

        break;

      case STAGE_3_3_WAITFORFIRSTID:

        aosDbgPrintf(">>> 3-3 (1st ID)\n");

        break;

      case STAGE_3_3_WAITFORIDORSIG:

        aosDbgPrintf(">>> 3-3 (ID/sig)\n");

        break;

      case STAGE_3_3_WAITFORID:

        aosDbgPrintf(">>> 3-3 (ID)\n");

        break;

      case STAGE_3_4_FINISH:

        aosDbgPrintf(">>> 3-4 (finish)\n");

        break;

      case STAGE_3_4_ABORT_ACTIVE:

        aosDbgPrintf(">>> 3-4 (active abort)\n");

        break;

      case STAGE_3_4_ABORT:

        aosDbgPrintf(">>> 3-4 (abort)\n");

        break;

    }

#endif

    // reset wfe flag for the next iteration

    flags.wfe_next = true;

    // waiting for events (may be skipped)

    if (flags.wfe) {

      // wait for any event to occur

      aosDbgPrintf("WFE...");

      eventmask = chEvtWaitAnyTimeout(ALL_EVENTS, chTimeUS2I(AOS_SYSTEM_SSSP_TIMEOUT));

      aosDbgPrintf("\t0x%08X", eventmask);

    } else {

      aosDbgPrintf("WFE skipped");

      eventmask = 0;

    }

    aosSysGetUptime(&uptime);

    aosDbgPrintf("\t%04ums\n", (uint32_t)(uptime / MICROSECONDS_PER_MILLISECOND));

    /*

     * execute some general tasks and high priority events

     */

    // no event occurred at all

    if ((flags.wfe) && (eventmask == 0)) {

      aosDbgPrintf("ERR: no evt\n");

      // enforce timeout event

      chEvtBroadcast(&eventSourceTimeout);

      continue;

    }

    // if an IO event occurred

    if (eventmask & _eventListenerIO.events) {

      ioflags = chEvtGetAndClearFlags(&_eventListenerIO);

      aosDbgPrintf("INFO: IO evt (0x%08X)\n", ioflags);

      // a power-down event occurred

      if (ioflags & MODULE_SSSP_EVENTFLAGS_PD) {

        aosDbgPrintf("PD evt\n");

        // deactivate S and UP

        aosDbgPrintf("disabling S\n");

        apalControlGpioSet(&moduleSsspGpioSync, APAL_GPIO_OFF);

#if (AMIROOS_CFG_SSSP_STACK_END != true)

        aosDbgPrintf("disabling UP\n");

        apalControlGpioSet(&moduleSsspGpioUp, APAL_GPIO_OFF);

#endif

        // set shutdown flag and exit the loop

        shutdown = AOS_SHUTDOWN_PASSIVE;

        break;

      }

      // the S signal was deactivated

      if (ioflags & MODULE_SSSP_EVENTFLAGS_SYNC) {

        apalControlGpioState_t sstate;

        apalControlGpioGet(&moduleSsspGpioSync, &sstate);

        if (sstate == APAL_GPIO_ON) {

          aosDbgPrintf("S evt (enabled)\n");

        } else {

          aosDbgPrintf("S evt (disabled)\n");

          // either finish or abort

          if ((stage == STAGE_3_3_WAITFORID) && (aos.sssp.moduleId != 0)) {

            stage = STAGE_3_4_FINISH;

          } else if (stage != STAGE_3_4_ABORT) {

            stage = STAGE_3_4_ABORT_ACTIVE;

          }

        }

      }

    }

    // an OS event occurred

    if (eventmask & _eventListenerOS.events) {

      aosDbgPrintf("WARN: OS evt\n");

      // get the flags

      eventflags_t oseventflags = chEvtGetAndClearFlags(&_eventListenerOS);

      // there should be no OS events at this point

#ifdef MODULE_SSSP_STARTUP_3_OSEVENT_HOOK

      MODULE_SSSP_STARTUP_3_OSEVENT_HOOK(eventmask, eventflags);

#else

      _unexpectedEventError(eventmask, oseventflags);

#endif

    }

    // if a CAN event occurred

    if ((eventmask & eventListenerCan.events)) {

      aosDbgPrintf("CAN evt\n");

      // fetch message

      if (flags.wfe) {

        canReceiveTimeout(&MODULE_HAL_CAN, CAN_ANY_MAILBOX, &canRxFrame, TIME_IMMEDIATE);

        aosDbgPrintf("CAN <- 0x%03X\n", canRxFrame.SID);

      }

      // identify and handle abort messgaes

      if (canRxFrame.SID == SSSP_STACKINIT_CANMSGID_ABORT) {

        stage = STAGE_3_4_ABORT;

      }

      // warn if a unexpected message was received

      else if ((canRxFrame.SID != SSSP_STACKINIT_CANMSGID_INIT) &&

               (canRxFrame.SID != SSSP_STACKINIT_CANMSGID_MODULEID)) {

        aosDbgPrintf("WARN: unknown msg\n");

      }

      // any further pending messages are fetched at the end of the loop

    }

    // if a timeout event occurred

    if (eventmask & eventListenerTimeout.events) {

      aosDbgPrintf("timeout evt\n");

      // is handled at the end of the loop (or must be cleared by FSM)

    }

    // if a delay event occurred

    if (eventmask & eventListenerDelay.events) {

      aosDbgPrintf("delay evt\n");

      // is handled by FSM

    }

    /*

     * this is the actual FSM

     */

    switch (stage) {

      case STAGE_3_1:

      {

        aos.sssp.stage = AOS_SSSP_STARTUP_3_1;

        // there was no event at all (skipped wfe)

        if (eventmask == 0 && flags.wfe == false) {

#if (AMIROOS_CFG_SSSP_MASTER == true)

          // initialize the stage by transmitting an according CAN message

          aosDbgPrintf("CAN -> init\n");

          canTxFrame.DLC = 0;

          canTxFrame.SID = SSSP_STACKINIT_CANMSGID_INIT;

          if (canTransmitTimeout(&MODULE_HAL_CAN, CAN_ANY_MAILBOX, &canTxFrame, TIME_IMMEDIATE) != MSG_OK) {

            chEvtBroadcast(&eventSourceTimeout);

            break;

          }

          // activate S

          aosDbgPrintf("enabling S\n");

          apalControlGpioSet(&moduleSsspGpioSync, APAL_GPIO_ON);

#if (AMIROOS_CFG_SSSP_STACK_START == true)

          // proceed immediately

          stage = STAGE_3_2;

          flags.wfe_next = false;

#else

          // set the timeout timer

          chVTSet(&timerTimeout, chTimeUS2I(AOS_SYSTEM_SSSP_TIMEOUT), _ssspTimerCallback, &eventSourceTimeout);

          // proceed

          stage = STAGE_3_3_WAITFORFIRSTID;

#endif

#else

          // set the timeout timer

          chVTSet(&timerTimeout, chTimeUS2I(AOS_SYSTEM_SSSP_TIMEOUT), _ssspTimerCallback, &eventSourceTimeout);

#endif

        }

#if (AMIROOS_CFG_SSSP_MASTER != true)

        // a CAN message was received

        else if (eventmask & eventListenerCan.events) {

          // if an initiation message was received

          if (canRxFrame.DLC == 0 &&

              canRxFrame.RTR == CAN_RTR_DATA &&

              canRxFrame.IDE == CAN_IDE_STD &&

              canRxFrame.SID == SSSP_STACKINIT_CANMSGID_INIT) {

            aosDbgPrintf("init msg\n");

            // reset the timeout timer and clear pending flags

            chVTReset(&timerTimeout);

            chEvtWaitAnyTimeout(eventListenerTimeout.events, TIME_IMMEDIATE);

            eventmask &= ~(eventListenerTimeout.events);

            // activate S

            aosDbgPrintf("enabling S\n");

            apalControlGpioSet(&moduleSsspGpioSync, APAL_GPIO_ON);

#if (AMIROOS_CFG_SSSP_STACK_START == true)

            // proceed

            stage = STAGE_3_2;

            flags.wfe_next = false;

#else

            // set the timeout timer

            chVTSet(&timerTimeout, chTimeUS2I(AOS_SYSTEM_SSSP_TIMEOUT), _ssspTimerCallback, &eventSourceTimeout);

            // proceed

            stage = STAGE_3_3_WAITFORFIRSTID;

#endif

          }

        }

#endif

        break;

      } /* end of STAGE_3_1 */

      case STAGE_3_2:

      {

#if (AMIROOS_CFG_SSSP_STACK_START == true)

        aos.sssp.stage = AOS_SSSP_STARTUP_3_2;

        // if this stage was just entered

        if (flags.wfe == false) {

          // set the module ID

          aos.sssp.moduleId = 1;

          // broadcast module ID

          aosDbgPrintf("CAN -> ID (%u)\n", aos.sssp.moduleId);

          canTxFrame.DLC = 4;

          canTxFrame.SID = SSSP_STACKINIT_CANMSGID_MODULEID;

          _serialize(canTxFrame.data8, aos.sssp.moduleId, 4);

          if (canTransmitTimeout(&MODULE_HAL_CAN, CAN_ANY_MAILBOX, &canTxFrame, TIME_IMMEDIATE) != MSG_OK) {

            chEvtBroadcast(&eventSourceTimeout);

            break;

          }

#if (AMIROOS_CFG_SSSP_STACK_START != true) || (AMIROOS_CFG_DBG == true)

          lastid = aos.sssp.moduleId;

#endif

#if (AMIROOS_CFG_SSSP_STACK_END == true)

          // sequence is already over

          // deactivate S

          aosDbgPrintf("disabling S\n");

          apalControlGpioSet(&moduleSsspGpioSync, APAL_GPIO_OFF);

          // proceed

          stage = STAGE_3_3_WAITFORID;

#else

          // set the delay timer so the UP signal is activated later

          chVTSet(&timerDelay, chTimeUS2I(AMIROOS_CFG_SSSP_SIGNALDELAY), _ssspTimerCallback, &eventSourceDelay);

#endif

        }

        // if a delay event occurred

        if (eventmask & eventListenerDelay.events) {

          // activate UP

          aosDbgPrintf("enabling UP\n");

          apalControlGpioSet(&moduleSsspGpioUp, APAL_GPIO_ON);

          // deactivate S

          aosDbgPrintf("disabling S\n");

          apalControlGpioSet(&moduleSsspGpioSync, APAL_GPIO_OFF);

          // explicitely clear timeout event flag

          chEvtWaitAnyTimeout(eventListenerTimeout.events, TIME_IMMEDIATE);

          eventmask &= ~(eventListenerTimeout.events);

          // proceed

          stage = STAGE_3_3_WAITFORID;

        }

#endif

        break;

      } /* end of STAGE_3_2 */

      case STAGE_3_3_WAITFORFIRSTID:

      {

#if (AMIROOS_CFG_SSSP_STACK_START != true)

        aos.sssp.stage = AOS_SSSP_STARTUP_3_3;

        // a CAN message was received

        if (eventmask & eventListenerCan.events) {

          // if an ID message was received

          if (canRxFrame.DLC == 4 &&

              canRxFrame.RTR == CAN_RTR_DATA &&

              canRxFrame.IDE == CAN_IDE_STD &&

              canRxFrame.SID == SSSP_STACKINIT_CANMSGID_MODULEID) {

            aosDbgPrintf("ID (%u)\n", (uint32_t)_deserialize(canRxFrame.data8, 4));

            // validate received ID

            if (lastid < _deserialize(canRxFrame.data8, 4)) {

              // store received ID

              lastid = _deserialize(canRxFrame.data8, 4);

              // restart timeout timer

              chVTSet(&timerTimeout, chTimeUS2I(AOS_SYSTEM_SSSP_TIMEOUT), _ssspTimerCallback, &eventSourceTimeout);

              // proceed

              stage = STAGE_3_3_WAITFORIDORSIG;

            } else {

              aosDbgPrintf("ERR: invalid ID\n");

              // abort

              stage = STAGE_3_4_ABORT_ACTIVE;

              flags.wfe_next = false;

            }

            // explicitely clear timeout event flag

            chEvtWaitAnyTimeout(eventListenerTimeout.events, TIME_IMMEDIATE);

            eventmask &= ~(eventListenerTimeout.events);

          }

        }

#endif

        break;

      } /* end of STAGE_3_3_WAITFORFIRSTID */

      case STAGE_3_3_WAITFORIDORSIG:

      {

#if (AMIROOS_CFG_SSSP_STACK_START != true)

        aos.sssp.stage = AOS_SSSP_STARTUP_3_3;

        // a CAN message was received

        if (eventmask & eventListenerCan.events) {

          // if an ID message was received

          if (canRxFrame.DLC == 4 &&

              canRxFrame.RTR == CAN_RTR_DATA &&

              canRxFrame.IDE == CAN_IDE_STD &&

              canRxFrame.SID == SSSP_STACKINIT_CANMSGID_MODULEID) {

            aosDbgPrintf("ID (%u)\n", (uint32_t)_deserialize(canRxFrame.data8, 4));

            // validate received ID

            if (lastid < _deserialize(canRxFrame.data8, 4)) {

              // store received ID

              lastid = _deserialize(canRxFrame.data8, 4);

              // restart timeout timer

              chVTSet(&timerTimeout, chTimeUS2I(AOS_SYSTEM_SSSP_TIMEOUT), _ssspTimerCallback, &eventSourceTimeout);

            } else {

              aosDbgPrintf("ERR: invalid ID\n");

              // abort

              stage = STAGE_3_4_ABORT_ACTIVE;

              flags.wfe_next = false;

            }

            // explicitely clear timeout event flag

            chEvtWaitAnyTimeout(eventListenerTimeout.events, TIME_IMMEDIATE);

            eventmask &= ~(eventListenerTimeout.events);

          }

        }

        // if an IO event was received (DN signal)

        if ((eventmask & _eventListenerIO.events) && (ioflags & MODULE_SSSP_EVENTFLAGS_DN)) {

          aosDbgPrintf("DN evt\n");

          // reset timeout timer

          chVTReset(&timerTimeout);

          chEvtWaitAnyTimeout(eventListenerTimeout.events, TIME_IMMEDIATE);

          eventmask &= ~(eventListenerTimeout.events);

          // increment and broadcast ID

          aos.sssp.moduleId = lastid + 1;

          aosDbgPrintf("CAN -> ID (%u)\n", aos.sssp.moduleId);

          canTxFrame.DLC = 4;

          canTxFrame.SID = SSSP_STACKINIT_CANMSGID_MODULEID;

          _serialize(canTxFrame.data8, aos.sssp.moduleId, 4);

          if (canTransmitTimeout(&MODULE_HAL_CAN, CAN_ANY_MAILBOX, &canTxFrame, TIME_IMMEDIATE) != MSG_OK) {

            chEvtBroadcast(&eventSourceTimeout);

            break;

          }

          // set delay timer

          chVTSet(&timerDelay, chTimeUS2I(AMIROOS_CFG_SSSP_SIGNALDELAY), _ssspTimerCallback, &eventSourceDelay);

        }

        // if a delay event occurred

        if (eventmask & eventListenerDelay.events) {

#if (AMIROOS_CFG_SSSP_STACK_END != true)

          // activate UP

          aosDbgPrintf("enabling UP\n");

          apalControlGpioSet(&moduleSsspGpioUp, APAL_GPIO_ON);

#endif

          // deactivate S

          aosDbgPrintf("disabling S\n");

          apalControlGpioSet(&moduleSsspGpioSync, APAL_GPIO_OFF);

          // reset the timeout timer

          chVTSet(&timerTimeout, chTimeUS2I(AOS_SYSTEM_SSSP_TIMEOUT), _ssspTimerCallback, &eventSourceTimeout);

          chEvtWaitAnyTimeout(eventListenerTimeout.events, TIME_IMMEDIATE);

          eventmask &= ~(eventListenerTimeout.events);

          // proceed

          stage = STAGE_3_3_WAITFORID;

        }

#endif

        break;

      } /* end of STAGE_3_3_WAITFORIDORSIG */

      case STAGE_3_3_WAITFORID:

      {

        aos.sssp.stage = AOS_SSSP_STARTUP_3_3;

#if (AMIROOS_CFG_SSSP_STACK_END != true)

        // a CAN message was received

        if (eventmask & eventListenerCan.events) {

          // if an ID message was received

          if (canRxFrame.DLC == 4 &&

              canRxFrame.RTR == CAN_RTR_DATA &&

              canRxFrame.IDE == CAN_IDE_STD &&

              canRxFrame.SID == SSSP_STACKINIT_CANMSGID_MODULEID) {

#if (AMIROOS_CFG_SSSP_STACK_START != true) || (AMIROOS_CFG_DBG == true)

            // Plausibility of the received ID is not checked at this point but is done by other modules still in a previous stage.

            lastid = _deserialize(canRxFrame.data8, 4);

            aosDbgPrintf("ID (%u)\n", lastid);

#endif

            // restart timeout timer

            chVTSet(&timerTimeout, chTimeUS2I(AOS_SYSTEM_SSSP_TIMEOUT), _ssspTimerCallback, &eventSourceTimeout);

            chEvtWaitAnyTimeout(eventListenerTimeout.events, TIME_IMMEDIATE);

            eventmask &= ~(eventListenerTimeout.events);

          }

        }

#endif

        break;

      } /* end of STAGE_3_3_WAITFORID */

      case STAGE_3_4_FINISH:

      {

        aos.sssp.stage = AOS_SSSP_STARTUP_3_4;

        // if an IO event was received (S signal)

        if ((eventmask & _eventListenerIO.events) && (ioflags & MODULE_SSSP_EVENTFLAGS_SYNC)) {

          // reset the timeout timer

          chVTReset(&timerTimeout);

          chEvtWaitAnyTimeout(eventListenerTimeout.events, TIME_IMMEDIATE);

          eventmask &= ~(eventListenerTimeout.events);

          //set the delay timer

          chVTSet(&timerDelay, chTimeUS2I(AOS_SYSTEM_SSSP_TIMEOUT), _ssspTimerCallback, &eventSourceDelay);

        }

        // if a CAN event was received

        if (eventmask & eventListenerCan.events) {

          // if an abort message was received

          if (canRxFrame.SID == SSSP_STACKINIT_CANMSGID_ABORT) {

            aosDbgPrintf("abort msg\n");

            // reset the delay timer

            chVTReset(&timerDelay);

            chEvtWaitAnyTimeout(eventListenerDelay.events, TIME_IMMEDIATE);

            eventmask &= ~(eventListenerDelay.events);

            // proceed

            stage = STAGE_3_4_ABORT;

          }

        }

        // if a delay timer event occurred

        if (eventmask & eventListenerDelay.events) {

          aosDbgPrintf("sequence sucessful\n");

          // sequence finished sucessfully

          flags.loop = false;

        }

        break;

      } /* end of STAGE_3_4_FINISH */

      case STAGE_3_4_ABORT_ACTIVE:

      {

        aos.sssp.stage = AOS_SSSP_STARTUP_3_4;

        // emit abort message

        canTxFrame.DLC = 0;

        canTxFrame.SID = SSSP_STACKINIT_CANMSGID_ABORT;

        canTransmitTimeout(&MODULE_HAL_CAN, CAN_ANY_MAILBOX, &canTxFrame, TIME_INFINITE);

        aosDbgPrintf("CAN -> abort\n");

        // clear timeout flag

        eventmask &= ~(eventListenerTimeout.events);

        // proceed immediately

        stage = STAGE_3_4_ABORT;

        flags.wfe_next = false;

        break;

      } /* end of STAGE_3_4_ABORT_ACTIVE */

      case STAGE_3_4_ABORT:

      {

        aos.sssp.stage = AOS_SSSP_STARTUP_3_4;

        // deactivate S

        aosDbgPrintf("disabling SYNC\n");

        apalControlGpioSet(&moduleSsspGpioSync, APAL_GPIO_OFF);

        // invalidate module ID

        aos.sssp.moduleId = 0;

        // if an IO event was received (S signal)

        if ((eventmask & _eventListenerIO.events) && (ioflags & MODULE_SSSP_EVENTFLAGS_SYNC)) {

          aosDbgPrintf("sequence aborted\n");

          // exit the sequence

          flags.loop = false;

        }

        break;

      } /* end of STAGE_3_4_ABORT */

    } /* end of switch(stage) */

    // fetch pending CAN message (if any)

    if ((eventmask & eventListenerCan.events) && (canReceiveTimeout(&MODULE_HAL_CAN, CAN_ANY_MAILBOX, &canRxFrame, TIME_IMMEDIATE) == MSG_OK)) {

      aosDbgPrintf("CAN <- 0x%03X\n", canRxFrame.SID);

      flags.wfe_next = false;

    }

    // handle unhandled timeout events

    if (eventmask & eventListenerTimeout.events) {

      aosDbgPrintf("ERR: timeout evt\n");

      // abort

      flags.wfe_next = false;

      stage = STAGE_3_4_ABORT_ACTIVE;

    }

    // apply wfe value for next iteration

    flags.wfe = flags.wfe_next;

  } /* end of FSM loop */

  // unregister all events (timeout, delay, CAN receive)

  chEvtUnregister(&eventSourceTimeout, &eventListenerTimeout);

  chEvtUnregister(&eventSourceDelay, &eventListenerDelay);

  chEvtUnregister(&MODULE_HAL_CAN.rxfull_event, &eventListenerCan);

  // clear any pending events (timeout, delay, CAN receive)

  chEvtWaitAllTimeout(TIMEOUTEVENT_MASK | DELAYEVENT_MASK | CANEVENT_MASK, TIME_IMMEDIATE);

  // reset all control signals

#if (AMIROOS_CFG_SSSP_STACK_END != true)

  aosDbgPrintf("disabling UP\n");

  apalControlGpioSet(&moduleSsspGpioUp, APAL_GPIO_OFF);

#endif

  aosDbgPrintf("disabling S\n");

  apalControlGpioSet(&moduleSsspGpioSync, APAL_GPIO_OFF);

  aosSysGetUptime(&uptime);

  aosDbgPrintf("done\t%04ums\n", (uint32_t)(uptime / MICROSECONDS_PER_MILLISECOND));

  return shutdown;

}

#endif /* AMIROOS_CFG_SSSP_ENABLE == true */

/**

 * @brief   Application entry point.

 */

int main(void)

{

  // local variables

  eventmask_t eventmask = 0;

  eventflags_t eventflags = 0;

  eventflags_t ioeventflagsmask = AMIROOS_CFG_MAIN_LOOP_IOEVENT_MASK;

  aos_shutdown_t shutdown = AOS_SHUTDOWN_NONE;

#if defined(AMIROOS_CFG_MAIN_EXTRA_THREAD_VARIABLES)

  AMIROOS_CFG_MAIN_EXTRA_THREAD_VARIABLES

#endif

  /*

   * ##########################################################################

   * # system initialization                                                  #

   * ##########################################################################

   */

#if defined(AMIROOS_CFG_MAIN_INIT_HOOK_0)

#if defined(AMIROOS_CFG_MAIN_INIT_HOOK_0_ARGS)

  AMIROOS_CFG_MAIN_INIT_HOOK_0(AMIROOS_CFG_MAIN_INIT_HOOK_0_ARGS);

#else

  AMIROOS_CFG_MAIN_INIT_HOOK_0();

#endif

#endif

  /* hardware, kernel, and operating system initialization */

  // ChibiOS/HAL and custom hal additions (if any)

  halInit();

#ifdef MODULE_INIT_HAL_EXTRA

  MODULE_INIT_HAL_EXTRA();

#endif

#if defined(AMIROOS_CFG_MAIN_INIT_HOOK_1)

#if defined(AMIROOS_CFG_MAIN_INIT_HOOK_1_ARGS)

  AMIROOS_CFG_MAIN_INIT_HOOK_1(AMIROOS_CFG_MAIN_INIT_HOOK_1_ARGS);

#else

  AMIROOS_CFG_MAIN_INIT_HOOK_1();

#endif

#endif

  // ChibiOS/RT kernel and custom kernel additions (if any)

  chSysInit();

#ifdef MODULE_INIT_KERNEL_EXTRA

  MODULE_INIT_KERNEL_EXTRA();

#endif

#if defined(AMIROOS_CFG_MAIN_INIT_HOOK_2)

#if defined(AMIROOS_CFG_MAIN_INIT_HOOK_2_ARGS)

  AMIROOS_CFG_MAIN_INIT_HOOK_2(AMIROOS_CFG_MAIN_INIT_HOOK_2_ARGS);

#else

  AMIROOS_CFG_MAIN_INIT_HOOK_2();

#endif

#endif

  // AMiRo-OS and custom OS additions (if any)

#if (AMIROOS_CFG_SHELL_ENABLE == true)

  aosSysInit(moduleShellPrompt);

#else

  aosSysInit();

#endif

#ifdef MODULE_INIT_OS_EXTRA

  MODULE_INIT_OS_EXTRA();

#endif

#if defined(AMIROOS_CFG_MAIN_INIT_HOOK_3)

#if defined(AMIROOS_CFG_MAIN_INIT_HOOK_3_ARGS)

  AMIROOS_CFG_MAIN_INIT_HOOK_3(AMIROOS_CFG_MAIN_INIT_HOOK_3_ARGS);

#else

  AMIROOS_CFG_MAIN_INIT_HOOK_3();

#endif

#endif

#if (AMIROOS_CFG_TESTS_ENABLE == true)

#if defined(MODULE_INIT_TESTS)

  MODULE_INIT_TESTS();

#else

  #warning "MODULE_INIT_TESTS() not defined"

#endif

#endif

#if defined(AMIROOS_CFG_MAIN_INIT_HOOK_4)

#if defined(AMIROOS_CFG_MAIN_INIT_HOOK_4_ARGS)

  AMIROOS_CFG_MAIN_INIT_HOOK_4(AMIROOS_CFG_MAIN_INIT_HOOK_4_ARGS);

#else

  AMIROOS_CFG_MAIN_INIT_HOOK_4();

#endif