Hello everyone!
Is there any way to downgrade the firmware from version 7 to version 6 on the B20?
I'm curious what the reason for wanting to downgrade. I think you lose the 'morecontrol' dev mode but should still be able to use the old dev mode (i think somewhere in this thread someone posted the steps to get into dev mode if you aren't upgraded to the newer software).
That said, I would think it's basically the same as upgrading. You'll need to find the corresponding 'old' sd card image and get it on an sd card. Once that is installed in the machine and booted, you should be able to do the steps on an earlier page to 'downgrade' the firmware on the microcontroller (using the files on the sd card) to match the sd card image version. The newer microcontroller firmware may be backwards compatible with the sd card image so the second half may not even be necessary if you can verify everything works a expected. Please report back your experience.
I'm now on brew 25 or 30 on my original b20 and 15ish on the second one that i fixed from eBay. So far so good.
One thing to note (may be related to my configuration) is that my second B20 had an issue where it would boot fine and after about 30 second just hard freeze. I found that the machine generates log files on the sd card. It had been left on for long periods of time during which the logs filled up the sd card which seemed to cause it to lock up shortly after boot. Interestingly enough, while locked up i could still SSH into the machine and was able to see the SD card was maxed out. After deleting several gigs of old log files it was back to new.
A second thing I've noticed only on my ebay machine (that was manually updated) is that during cleaning and occasionally during a brew, it will fill with water as it should, then say it has no water source. After i hit ok it continues like nothing ever happened (didn't continue filling or anything). More of an annoyance than anything else but wondering if anyone else has experienced this or solved this issue.