State Machine

Deterministic state machine for the engine start / run / shutdown cycle.

Header: core/ecu_sm.h

enum ecu_state_t

Engine operating states.

Values:

enumerator ECU_STATE_OFF: Controller inactive.

enumerator ECU_STATE_PRESTART: Sensor warmup / self-check.

enumerator ECU_STATE_SPINUP: Starter driving shaft to minimum RPM.

enumerator ECU_STATE_IGNITION: Igniter + first fuel injection.

enumerator ECU_STATE_RAMP: Accelerating to target RPM.

enumerator ECU_STATE_RUN: Stable operation under PID control.

enumerator ECU_STATE_COOLDOWN: Lowering EGT before shutdown.

enumerator ECU_STATE_SHUTDOWN: Engine stopped, outputs safe.

enumerator ECU_STATE_FAULT: Safety violation — awaiting reset.

enum sm_result_t

Result of a state transition attempt.

Values:

enumerator SM_NO_CHANGE: State unchanged.

enumerator SM_TRANSITION: Transition occurred.

typedef void (*ecu_sm_callback_t)(ecu_state_t state, void *ctx): Callback invoked on state entry or exit.

void ecu_sm_init(ecu_sm_t *sm)

Initialise the state machine (state = OFF).

Parameters:

sm – [out] State machine context.

sm_result_t ecu_sm_transition(ecu_sm_t *sm, ecu_state_t next, ecu_time_t now)

Attempt a state transition.

Parameters:

sm – [inout] State machine context.
next – [in] Target state.
now – [in] Current timestamp (ms).

Returns:

SM_TRANSITION on success, SM_NO_CHANGE otherwise.

ecu_state_t ecu_sm_state(const ecu_sm_t *sm)

Get the current state.

Parameters:

sm – [in] State machine context.

Returns:

Current state.

const char *ecu_sm_state_name(ecu_state_t state)

Get a human-readable name for the given state.

Parameters:

state – [in] State value.

Returns:

Null-terminated state name string.

void ecu_sm_set_callbacks(ecu_sm_t *sm, ecu_sm_callback_t on_enter, ecu_sm_callback_t on_exit, void *ctx)

Register entry/exit callbacks.

Parameters:

sm – [inout] State machine context.
on_enter – [in] Called after entering a new state (may be NULL).
on_exit – [in] Called before leaving the current state (may be NULL).
ctx – [in] User context forwarded to callbacks.

void ecu_sm_set_timeout(ecu_sm_t *sm, ecu_time_t timeout_ms)

Set a timeout for the current state.

Parameters:

sm – [inout] State machine context.
timeout_ms – [in] Timeout in milliseconds (0 = disable).

bool ecu_sm_timed_out(const ecu_sm_t *sm, ecu_time_t now)

Check whether the current state has exceeded its timeout.

Parameters:

sm – [in] State machine context.
now – [in] Current timestamp (ms).

Returns:

true if timed out.

ECU_STATE_COUNT: Total number of states.

struct ecu_sm_t

#include <ecu_sm.h>

State machine runtime context.

Public Members

ecu_state_t current: Current state.

ecu_time_t state_enter_time: Timestamp of last entry.

ecu_time_t timeout_ms: Per-state timeout (0 = none).

ecu_sm_callback_t on_enter: Entry callback (may be NULL).

ecu_sm_callback_t on_exit: Exit callback (may be NULL).

void *cb_ctx: User context for callbacks.