State-Machine Design and Validation
Model operating modes, events, transitions, guards and timeouts explicitly.
Arduino-compatible frameworks, ESP-IDF/FreeRTOS, PIC/AVR/STM32/RP-class systems; apply exact vendor documentation for the selected MCU.Architecture
Event queue → transition table → entry/action/exit handlers → observable state and fault path.
Security and recovery risks
- Provide a safe default for unknown state.nPersist only stable state, not transient execution position.nBound event queues and define overflow handling.
Implementation procedure
- List mutually exclusive states.nDefine allowed events and guarded transitions.nAdd timeout and invalid-event behaviour.nGenerate a switch/table skeleton below.nTest every transition, including recovery.
Starter code / configuration
typedef enum { ST_BOOT, ST_IDLE, ST_RUN, ST_ERROR } state_t;Verification evidence
| Test | Expected | Evidence |
|---|---|---|
| Nominal boot | Correct version and hardware revision reported | Captured boot log |
| Fault recovery | Defined safe state and reset reason | Fault-injection record |
| Power cycle | No corrupt configuration or unsafe output | Repeated-cycle log |
Required release artifacts
- Versioned firmware binary and SHA-256
- Source revision / build identifier
- Board and hardware-revision compatibility list
- Test report and known limitations
- Recovery image and factory-reset procedure
- Provisioning/calibration schema
- Release approval record
Local browser tools
Firmware production workbench
A/B update exercise
OTA and automatic rollback simulator
Advance one validated stage at a time. A failed boot test returns the device to the previous slot.
- Running confirmed firmware from Slot A.
Release gate
Production-readiness checklist
A downloadable release decision is generated only after every mandatory control is confirmed.