I2c cable purchase advice

I just got a Teletype used and it didn’t have the i2c cable with it. Recommendations for where to purchase? I have an Ansible, Earthsea, and Just Friends i’d like to connect to it. Should the cable be longer that the one that normally comes with Teletype because of Just Friends? Any recommendations on which cable to get our very welcome!


Thanks! I’d like to get one that has the multiple sockets on it, like what is sent with Teletype. I’m sure if I call Mouser they can help me find one.

I’d recommmend doing the i2c bus, having all the sockets on one cable is a problem if one of the sockets disconnects from a module.

you can add extra headers yourself with a pair of pliers. get them here:

also check this out:

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Oooo, nice, thanks Brian! I’ll order from OSH Park.

If you’ve got 3 devices connected, you should consider using the powered II board instead, especially if you’ll be adding more in the future.

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If I have Ansible, Earthsea, and Just Friends connected by the unpowered bus, or just by the ribbon cable, will this be too much? Is the powered bus necessary in this situation, or with more modules, or with the expanders?

I don’t know for definite, @bpcmusic is probably the expert on these matters…

that should be fine, but keep in mind the JF firmware isn’t complete yet. generally the ergonomics of a bus board are much improved over a multi-ribbon.

Haven’t tested these three together explicitly, but the rule of thumb seems to be that three are fine under regular use cases. (Not sure about hyper-aggressive polling that has been enabled by the latest improvements from @sam and @scanner_darkly.)

If you connect four or more, you need the powered bus board.

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Ok, unpowered bus ordered. Thanks!

I’m looking into ordering some i2c cables for Teletype and JF (which I’ll hopefully have after the next stock release) and saw these on Amazon. As there are several different types in this pack, are some of these the right ones for connecting TT to JF?


i don’t think so… but these for sure work. they’re what i bought!


Hi! I’m a totally electronics noob. Right now I have a Teletype (one of the newest units). I’ve recently purchased two Teletype expanders (TXo+ and TXi) and I have plans to acquire Ansible and Just Friends modules. What hardware I need? From what I’ve read I think I need a Teletype backpack (where I could get one?) and i2c cables (like the last ones @reallyok mentioned in this thread?). I don’t know if that’s important but Teletype is going to power Grid too (via two > one module).

i would try it first without a backpack and see if it’s reliable enough, then try updating the firmware on just friends to the latest, which will enable additional pullups and see if that helps. if it’s still not reliable, then a backpack would be something to consider.

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Hey everyone,

I wanted to check if these cables would work before I jump in and purchase

Thank you!


They are the right kind, but check if 21cm isn’t too short for you.

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Thank you for that! Planning on having Teletype + Ansible right next to each other connected via I2C so I think 21cm should be all good.

As of right now, I have my modules all daisy-chained with i2c within a single case and it’s working great. I’m beginning to consider getting a 16n faderbank to use with my i2c group in my main case but wanted to ask what other people are doing for wiring this up?

I had a thought to wire up an i2c cable in my main case to terminate with a 3.5mm input jack on my case so that I could patch a 3.5mm cable between the main case and the 16n. Is that feasible? Have others done this or how are you connecting i2c across devices?

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