OTA

[AJ-alexx]

Automatic update of the transmitters via OTA doesn't work yet? Can I already mount the stations again permanently if they are set to OTA and have contact with Breezedude ground stations, where they get their updates?

Best Regards
Alex

[thezenox]

OTA is still under beta testing on some station I have physical access to. So far it did work very reliably and did not cause any problems.

How to OTA update

• OTA updates require any V1.0 firmware (with new bootloader) installed.
• The functionality is enabled by default (but it can be disabled in the config file).
• To validate that you are the owner of the transmitter, read out the UUID with the Web analyzer. You will need it for registration of the ownership

How it works - non technical version

• A BD groundstation must be in range (the closer the better, I still need to figure out the working range. 2km line of sight was ok, 16km was not.)
• Target firmware version must be set in the database. A management website can be found here
• The transmitter checks for updates automatically once a hour. You can track the timing in the groundstation console.
• The update progress can be tracked in the web console of the groundstation and the LEDs of the transmitter PCB and takes 2-3 minutes on good connection.
• If the update is interrupted or fails, it will continue in the next session (1h later best case)
• A failed update should not break the device.

How it works - technical version

• The transmitter is emitting its current version (plus a random seed) once per hour and switches to listen mode for 15s.
• If a groundstation is receiving the signal, it is forwarding the request to the backend.
• The backend checks if an update is pending (firmware or config values)
• The backend is responding to the groundstation:
  a) a (encrypted) handshake and the download URL of the update file, if a update is pending:
  b) "no update", if up to date
• The groundstation sends the message to the transmitter (either data or just acknowledge)
• The transmitter checks the encryption of the handshake. If ok, it switches to 'update receive' mode:
• The groundstation downloads the firmware (binary file) and its checksum from the backend.

Now the actual update starts:

• First metadata is exchanged (see remarks below)
• The firmware is transmitted in 192byte chunks, each with a sequence number.
• The transmitter is requesting each chunk from the groundstation. if transmission fails, it will request for a resend (blue LED flash). If chunk was ok, it requests the next one (red led flash)
• If no data is received after a few retries, update session is aborted.
• If all chunks are transmitted, the checksum of the newly written flash bank is checked against the one provided by the backend. If it matches, a flag for the bootloader is set. (confirmed by a few long blue/red LED blinks)
• A reboot is triggered. the bootloader sees the flag and switches flash banks.

Remarks

• If any of the handshake packets is lost, the update will not start for this session.
• If multiple groundstations receive the update request, the backend will get multiple requests for the same station within a short wait time. The backend selects the groundstation with the best RSSI to perform the update. All others remain silent.
• If a groundstation reports "no update", the transmitter will not request again for 1h (currently, this may be extended to longer periods like 1day in future).
• A OTA update is limited to a 15min duration window in total. If the update fails within this window, it will continue in the next try (1h)
• if exchanged metadata is equal to the one stored in the second flash bank of the transmitter, it will continue an earlier session, starting with the last valid packed already transmitted. With this an aborted update can be continued instead of starting all over again each time.
• For firmware data transmission, both, groundstation and transmitter switches to a different LoRa radio setting than FANET. During the update, both are 'blocked' and not working in normal FANET mode.
• These differend LoRa settings can be tuned in the future, to e.g. select settings depending on the RSSI.
• The first update check is performed 10min after reset/boot (this delay can be shortened for testing in the config file)
• If you don't have a permanent groundstation in range, you can go for a picknic close to the transmitter, with a mobile groundstation and WiFi hotspot. The update process cannot be triggered externally, you need to wait up to 1h. If the handshake fails (cause of package loss...), you need to wait another hour and so on.

[thezenox]

I made a management website: devices.breezedude.de.
You can add your stations, send others invitations to join your station, apply OTA firmware updates and set OTA config updates.
You can also get a history of config and firmware changes and if they are pending or confirmed.

Uses passkey-only authentication. As I don't have a mailserver set up for recovery links yet, send me a message if you lost your account, I can create you a recovery link.

[thezenox]

Before you blindly mount the device out there again after the upgrade, please test OTA once on your desk.
There are devices with a bootloader not accepting the new firmware. Update behaves normal but after reboot the old version ist still there. (causing an infinite update loop every 10 minutes)
I did not find out where it does come from yet, because if I try to reproduce (flashing back the old 3.16 bootloader and doing the upgrade steps) it always works.

[AJ-alexx]

I actually had this problem once with a USB update; I had to apply it four times before the update was accepted. The station behaved normally, even reset itself, but didn't take the update. As I said, it only happened to me once.
Regarding version 1.04: for your information, on the Vario Naviter Oudi N, the pressure is now displayed correctly, but on the Breezedude map, an incorrect value appears—see test station name: AJ123 and REDAJ7T.

[thezenox]

mhm, ok. I will keep this in mind, maybe at some point I will find out some details. I did not check if it will accept the update after multiple tries. But that would be an interesting error then.

Yep, groundstations need an update, too. I will roll it out when everything is tested. Only occurs if no humidity data is present (WS85 UART and Davis 6410). I recommend enabling auto-update (stable-channel) of the groundstation, then it will just silently update automatically.

[thezenox]

claude found the problem with the ota not working on some devices: On the bootloader update it would just write new flash pages and not erase not used pages. So the data in the the flash region where the ota image would be written stays what was there before. Depending on the update history or if the device was once programmed with SWD (this erases the complete flash) recently it could be 0xFFs, 0x00s or just some random leftover data.
The V4.1 bootloader was checking for 0xFFs from the end of the bank to find the end of the firmware image to determine size to copy. If there were no 0xFF, it would not copy and skips. that is exactly what happend when a OTA update was not accepted. because there were non erased flash/leftovers, it would not find the end of the new app and skips copying.
If you flash the bootloader via SWD programmer, it will erase the whole flash and it works.

To fix this (in a clean way), a bootloader update is required. I put V4.1.8 to releases (for completeness).

I would maybe figure out a way to fix this OTA as well, by adding 0xFFs to the new binary to overwrite the whole flash by the update. but this might not work out because the slots are not equal in size. Because of that, and of clean fixing is a better idea anyway, I (or lets say claude) will rework the bootloader and the whole flash layout again to get two equally sized slots (and max out the slot size to ~119kb)
with this we are prepared for future updates in maximum binary size, but lose flexibility to add more virtual files to the flash drive as there is no unused flash left over.

So there will be another incompatible upgrade (V4.2 bootloader + V1.1 Firmware) coming soon. Sorry for that, but V1.0 was still beta to get OTA working, and I would say it went quite well.
As always: There is no need to upgrade, if your station is working perfectly.