Cold Storage IoT Embedded Product Development

Log to flash before you transmit. If the gateway is down or the BLE connection drops, the node has to keep recording. We use a ring buffer in the nRF's internal flash or an external SPI flash chip, with each record carrying a timestamp, sensor ID, and CRC.

Timestamp at the edge, not the cloud. Network latency and gateway reboots will wreck your audit trail if you rely on server time. The RTC stamps every sample.

Handle defrost cycles explicitly. A door opening or a defrost heater ramp isn't an alarm — it's a known event. We give the firmware a state machine so it can distinguish a 90-second excursion from a real failure.

Expose the logs. Compliance auditors want raw CSV or a signed export, not a pretty chart. We build a simple serial or BLE command interface that dumps the last N records in a documented format.