Define product scope and operating goals
- Confirm the node's primary function: measure temperature and humidity and report data over Wi-Fi and Bluetooth.
- Define the intended consumer-use context: indoor/outdoor use, expected ambient range, enclosure expectations, size targets, and user-facing behaviors.
- Set high-level low-power goals such as standby behavior, measurement/reporting interval, and whether USB power is continuous or only used for setup/charging-style powered operation.
Capture the power-input and protection requirements
- Define the USB-C power-input requirement as 5 V default sink operation only (no USB-PD negotiation in this phase).
- Record that the design must safely tolerate common source capabilities from 0.5 A to 3 A and must not assume more current than the attached source can provide.
- Capture required protection features at the requirements level: reverse-polarity protection, over-voltage protection (OVP), under-voltage lockout (UVLO), over-current protection (OCP), and consumer-use robustness.
- Note supporting consumer-use requirements such as ESD resilience, safe fault behavior, and protection against incorrect/poor-quality USB power sources.
Capture functional subsystem requirements
- MCU requirement: dual-radio Wi-Fi + Bluetooth capable device, with enough GPIO/interfaces for sensor, status, and provisioning needs.
- Sensor requirement: digital temperature/humidity sensor with defined accuracy, update rate, and interface expectations.
- Define system-level behaviors: startup, sensor sampling cadence, wireless provisioning/update behavior, normal reporting mode, and fault/status indication.
- Record any expected user or manufacturing interfaces such as debug/programming access, test points, LEDs, or buttons.
Translate requirements into Flux planning artifacts
- Create a top-level block diagram in Flux with these blocks: USB-C input, protection/power path, regulation, MCU/radios, sensor, user/status interface, and programming/test interface.
- Define interface boundaries and named nets at a conceptual level only (USB 5V input, protected power rail, logic rail, sensor interface, radio/antenna area, debug interface).
- Write acceptance criteria for the next phase so component research stays scoped: power budget target, required protections, radio capability, sensor interface, consumer-use constraints, and any certification/manufacturing considerations.
- Do not select exact parts yet; use this step only to lock the requirements and architecture boundaries for later schematic capture.