I got a Shimano SW-E6000 switch here, which I'd like to use for my custom eBike controller.
Ofc I could just get rid of the MCU inside and connect the buttons directly, but where's the fun then, eh?
What I know so far:
- The packaging says Di2, that's how I found this thread.
- Inside there's a 3.3V LDO and a MCU: 11XW marking
- The circuit looks very similiar to the SW-S705, just smaller package sizes
- I was able to power it with 5V and could see some weird AC waveforms on the oscilloscope, but they look different like Radiohead's
- Shimano references CAN bus a few times, e.g.
https://bike.shimano.com/en-EU/technologies/component/details/steps/drive-unit.html- There are two protocols, the older ACC and the newer Di2.
- Shimano support said StePs supports both protocols, that's why old and new components work. (Can't find the blog post anymore, but
- Since there's only two wires, Di2 might be SWCAN (that's what people say in other forums as well).
- OTOH there seem to be different protocols among Di2 components. There's a comment mentioning timed pulses
https://carltonbale.com/shimano-di2-everything-you-need-to-know/comment-page-5/#canbus_protocolI found this post in the German pedelec forum:
https://www.pedelecforum.de/forum/index.php?threads/optimierung-von-shimano-steps-systemen-mit-den-emax-softwarewerkzeugen.51623/page-178#post-1596705- That guy claims they have decapped, reverse engineered that chip:
- It's a custom chip based on Renesas RX
- The protocol is not "just simple CAN" but a "very special" proprietary protocol
- At least that sounds like it is somehow similiar to CAN - maybe some modified SWCAN that can be implemented without dedicated transceiver?
This video confirms @mark.s's results.
https://youtu.be/Dyn7XHsTmgI?t=530Note beside: that guy is claiming there is no way that Di2 could be CAN + power over a single wire, but he's only talking about regular two-wire CAN, but completely ignoring SW-CAN and possible proprietary modifications of it. Also there ist DCAN500, which is CAN-over-Powerline.
I found reddit posts from people saying that they were able to simply use regular CAN modules (like mcp2515) on SWCAN busses. Might be worth a try :O
@Radiohead: Can you give some more details on how you powered your SW-S705 and connected your osci?