Not a lawyer, but I went through this with a test lab for a BLE product. The modular grant covers the radio as long as you stay inside it: same antenna type and gain, no changes to output power, frequencies or modulation, and the module’s FCC ID shown on your label („Contains FCC ID …“). Updating your own application code doesn’t touch that. The host product still needs its own unintentional-emitter check (Part 15B), once, not per update. Ask your lab to put that in writing for your file, it’s a short email for them.
Where you could break the grant is if an update ever lets the radio config change, so lock that: the app should have no command or setting that changes bands or power.
On the Hermetry side, what I’d set up before the first real rollout:
- Register your signing public key under Firmware > Signing keys and keep „Allow unsigned images“ off on the tracker profile. Only an owner can add keys, and the device must refuse an image whose signature doesn’t verify, so build that check into your bootloader.
- Fill in Hardware models on each upload, so a rev B image never goes to rev A boards.
- Use Send in waves on the profile assignment, start with your own 10 test trackers.
- Leave „Allow updates over LTE“ off until you know the image size and your data plan, otherwise each tracker downloads it on cellular the moment it’s assigned.
- Report
current_fw_versionafter every connect. Hermetry only marks an update done when the new version actually shows up, and flags it if the old one comes back.
All on Firmware updates (OTA).