demo-epb/arch/swe/SWA-002.md

active, derived, header, level, normative, reviewed, links, asil

active	derived	header	level	normative	reviewed	links	asil
true	false	Apply Controller	1.2	true	null	SWE-001 SWE-002 SWE-003 SWE-004 SWE-005	D

SWA-002: Apply Controller

Responsibility

Central controller for apply, hold and release of the parking brake. ASIL-D core of the EPB software. Implemented in src/apply_controller.c.

Static view

@startuml
[Apply Controller] --> [Actuator Driver L] : apply/release
[Apply Controller] --> [Actuator Driver R] : apply/release
[Switch Debouncer] --> [Apply Controller] : sw_apply, sw_release
[Safety Manager] --> [Apply Controller] : auto_apply, hill_hold_request
[Apply Controller] --> [Display Manager] : status
[Apply Controller] <-- [Watchdog] : alive_check
@enduml

Provided interfaces

Status apply_ctrl_init(void);
void   apply_ctrl_step_50ms(const ApplyInputs* in);
EpbStatus apply_ctrl_get_status(void);

Dynamic behaviour

@startuml
[*] --> Released
Released --> Applying : apply_request & v_low
Applying --> Applied : current_target_reached
Applied --> Releasing : release_request & preconditions_ok
Applied --> Applied : 50ms hold check (re-clamp if needed)
Releasing --> Released : release_complete
Applying --> Error : timeout > 1500ms
Releasing --> Error : timeout > 1200ms
Error --> Released : reset & no fault
@enduml

Resources

• Stack: <= 384 B
• Worst-case timing: 350 us per call

Design decisions

Decision	Rationale
Static allocation, no heap	Determinism, MISRA C 21.3
State machine	Easier to verify, deterministic
50 ms step function	Synchronous with inclinometer sample rate

Mapping to requirements

Requirement	How covered
SWE-001	Hold state with periodic clamping-force check
SWE-002	Watchdog pet in step_50ms
SWE-003	sw_apply input is evaluated immediately
SWE-004	current-target detection via actuator-driver feedback