SBC Module (System Basis Chip)
Source: docs.foxbms.org — SBC
Files: src/app/driver/sbc/sbc.c, sbc.h, nxpfs85xx.c, nxpfs85xx.h
Vendor: NXP FS8x (3-Clause BSD licensed driver)
Function
SBC manages MCU power based on ignition signal:
| Mode | Condition |
|---|---|
| Running | Ignition present → SBC powers MCU normally |
| Standby | Ignition removed → MCU requests SBC standby |
| Power Down | No ignition in standby → SBC cuts MCU power |
| Restart | Ignition detected → SBC powers MCU again |
Hardware Watchdog
The SBC includes a hardware watchdog. If the MCU does not service the watchdog within the configured window, the SBC triggers a reset.
Key Discovery (POSIX Port)
SBC_STATEMACHINE_RUNNING = 2 (not 3)
The SYS state machine waits for SBC_GetState() to return SBC_STATEMACHINE_RUNNING. The enum value is 2, not 3 as might be assumed. Using the wrong value causes SYS to time out in INITIALIZATION and never reach RUNNING.
POSIX Port Status
- SBC init stubbed:
SBC_GetState()returnsSBC_STATEMACHINE_RUNNING(value 2) SBC_SetStateRequest()returns OK- Hardware watchdog not simulated (GA-24)
- NDA restriction: MC33FS830A0ES programming details not publicly available