Downgrading DI2 Firmware

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Re: Downgrading DI2 Firmware

Postby dj_oatmeal » Mon Jul 30, 2018 11:00 pm

Here is where I am at. ... 7.jpg?dl=0

The battery was originally v3.0.4(or 0.5) and went through the "upgrade" process as described using a renamed copy of old FW.
The shifter will not play so far. Etube sometimes says they won't work and that I need to upgrade etube and other times it tries to upgrade the FW. I haven't figured out the difference. When it says to upgrade the FW I let it try multiple times but nothing seems to happen.

The EW90A still won't take an "upgrade" using the exact same technique that worked on the seemingly more sophisticated battery.

The other thing missing is the option to use the RD6870 as 10 speed vs 11 speed. Using v2.5.2 I don't have that dropdown. That said the RD is working but just as 11 speed. Maybe it's a different version of Etube that has that feature?

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Re: Downgrading DI2 Firmware

Postby Duck! » Tue Jul 31, 2018 12:04 am

dj_oatmeal wrote:
The other thing missing is the option to use the RD6870 as 10 speed vs 11 speed. Using v2.5.2 I don't have that dropdown. That said the RD is working but just as 11 speed. Maybe it's a different version of Etube that has that feature?

RD-6870 has never had the possibility of being set up as 10-sp. In contrast to mechanical systems where the shift indexing is a function of the shifters, Di2 reverses it and has the derailleurs hard-programmed to index a particular way, with the shifters being the slaves.

As mentioned previously, there was a brief period early in the life of 9070/6870 where it was possible to upgrade a 6770 10-sp. system to 11-sp. simply by dropping in one of those rear derailleurs, although it was never actually supposed to work in conjunction with the FD-6770. A subsequent firmware update removed that accidental front/rear derailleur communication, meaning 6770 had to remain paired for 10-sp, and 9070 & 6870 could be mixed with each other, but not with FD-6770 for 11-sp.

You may be striking further problems by having some components that are too new to be downgradeable to older-spec firmware; the DN110 battery in particular springs to mind. If you want to go back far enough to mix 10 & 11-sp.derailleurs - they're the critical bits - you'll need to use a full complement of contemporary components that the relevant firmware was written for.
I had a thought, but it got run over as it crossed my mind.

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Re: Downgrading DI2 Firmware

Postby jawwy » Mon Sep 03, 2018 4:05 pm

vosadrian wrote:
lone rider wrote:Thanks Duck.

Doing that firmware upgrade is going to be your problem. You could do it yourself with either the shop tool or a BCR2 charger. There is even a way to connect a BCR2 to a DI2 system without the newer EW junction if you know someone you can borrow a BCR2 charger from. I have 2 bikes running internal battery with the EW67 earlier junction. I made an adapter that enables me to plug the BCR2 charger in to a free DI2 port (on shifters which have a spare port) for charging and programming (updates/settings).

Hi! Created/registered here as I have no real idea what I am doing :)
Very interested in this post, and I am hoping for some more information.
I have an Giant TCR which has the very original 6770 Di2, with the really old junction box (not sure of model number, but can find it) and I wish to upgrade the software, as I recently purchased the R8070 FD and RD and an 11 speed cassette. I was hoping that because I have never done a software upgrade on the bike, I could just put in the new di2 components and keep the old 6770 shifters and everything would be hunky dory. This wasn't to be however. From what I understand, because the generation gap between these components is rather large, the software must be updated first.
However, I am currently living in Chiang Mai in Thailand, and although some of the bike shops here are brilliant, I am struggling to find the
SM-PCE1 interface that I am supposed to use for the upgrade. I can, however, track down the BCR2 charger interface box thingy. I think. How would I go about plugging this charger into the bike to be able to do the software upgrade? Thanks so very much for your help.
I am dying to fit these new components on the bike and go 11 speed.

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Re: Downgrading DI2 Firmware

Postby vosadrian » Mon Sep 03, 2018 4:47 pm

I have a similar setup to you, but I have 6870 series FD and RD (and I run the internal battery). I do not have the new junction that plugs to BCR2 and I made a cable that can plug between a BCR2 charger and a spare port on my 6770 shifters. If you have a spare DI2 cable around, you could cut that up to make a cable. When you cut the cable, there is a red (+) and black (-) wire internally. You can connect these to the equivalent wires on the BCR2 charger and then plug the DI2 connector into the spare port on the shifter. In my case I did not want to modify the BCR2 charger so I used some 0.1" pitch pin header to plug into the BCR2 connector and then soldered the red and black wires to the header so it can be plugged into the BCR2 connector. Just make sure you plug it in the right way to avoid reverse polarity which could damage something. You can measure the voltage of the BCR2 connector pins with a multi-meter to determine the polarity.

Note that if you do this, you may find that the software recognises your setup as an invalid setup (it will expect to see the correct junction) in which case it may refuse to allow you to do anything. As stated earlier in this thread, earlier versions of the software are not as fussy with setup and can be used to upgrade firmware to later version than supported by the software (assuming you can get an old software version). I found that simply disconnecting all the parts except the ones you want to program (and the battery) can make the software happier also.

Good luck!

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