Tahoe - Technical Support

New firmware organisation

Note: This information applies only to Tahoe 681, 682 and 684 modems

Bootstrap and firmware
Firmware recovery
Safe firmware replacement
Firmware compression
Upgrade from older versions
Upgrade from 1.2.9 or later versions
Downgrade to 1.2.8 and older versions

Bootstrap and firmware

Since firmware release 1.2.9 we introduced a new organisation of the Flash memory containing the firmware. In previous releases the firmware occupied whole Flash memory. In order to change it to a recent version user had to erase the memory first, then upload a new firmware image. If the modem was rebooted before the file was completely uploaded (i.e. it stopped responding or the power went off) it become unusable - the Flash memory didn't contain a valid firmware and the modem didn't boot again.

Firmware (512 kB)

Fig. 1 - Flash organisation in releases up to 1.2.8

The 1.2.9 release was divided into two parts - a small part called bootstrap and the firmware itself compressed to preserve memory. The bootstrap will never be changed or erased - everytime you upgrade the firmware you erase and overwrite only a part of the Flash memory.

Bootstrap (64 kB)

Compressed firmware (448 kB)

Fig. 2 - Flash organisation in releases 1.2.9 and later

After power-up the bootstrap starts first, decompresses the firmware into RAM, checks its checksum and starts executing it.

Firmware recovery

If something goes wrong - i.e. the firmware image is invalid due to a mistake during upgrade - the bootstrap enters a recovery mode. Appropriate message is displayed on the serial console:

Bootstrap loader 1.2.8 (Tue Jul 12 00:17:44 CEST 2005) Press Ctrl+C to enter firmware recovery mode Checking CRC... Firmware CRC error (0x6eda3c2e, should be 0x4e5d386f) Entering firmware recovery mode - press Ctrl+R to reboot - press Ctrl+E to erase configuration Device will reboot if no file is sent in 5 minutes

Now the modem only responds to pings and TFTP request under standard IP address (10.0.0.1). You can send 'erase' and 'flash' files again to update the firmware.

Don't be confused because of bootstrap's version number. It will be diffrent from the firmware version and will rarely change.

Safe firmware replacement

Every time you send the 'erase' file only the 448 kB of the Flash memory are erased and when you send 'flash' file only these 448 kB are written. The bootstrap will remain unchanged and the modem will always boot up - in the worst case it will enter the firmware recovery mode. That's why the firmware upgrade is now perfectly safe.

Firmware compression

Thanks to the compression of the firmware we have more free space for new features in the future. The 1.2.8 firmware occupied 471 kB or 92% of the Flash memory. The 1.2.9 release takes only 274 kB or 54% of the memory.

Upgrade from older versions

We tried to make the firmware upgrade procedure exactly the same as in previous releases. The firmware image (t680-1.2.9.bin) contains both bootstrap and the firmware itself. When you upgrade from an older version you have to send an 'erase' file and then the new image under 'flash' name.

Be careful! Since you have an old firmware release in your modem the 'erase' file will delete the flash contents completely. The new, safe upgrade method will be available only when the modem works under the new firmware

When you send the 'flash' file the older firmware will write whole Flash contents - both bootstrap and firmware itself, because it cannot distinguish between them.

Upgrade from 1.2.9 or later versions

If you are upgrading a modem that already contains the 1.2.9 or later version the procedure will be the same - you have to send 'erase' and 'flash' files. In contrary the 'erase' file won't erase the bootstrap - only the remaining 448 kB. When you send the 'flash' file the modem will skip first 64 kB containing bootstrap and will start writing from the place where the compressed firmware should be placed.

Downgrade to 1.2.8 and older versions