DIY i2c cables

there are numerous ways to connect your i2c modules together.

quite simply you need to make a connection between the SDA, SCL, and GND pins. make sure they match.

these are good:

originally we were using 2x3 headers on 6 conductor ribbon cable:

you can of course put multiple headers (as many as you want) on the same cable.

this is not difficult. cut the ribbon. use some pliers. there’s a satisfying click when the headers lock.

recently links for these popped up, and they will work well. particularly if you heat-shrink the bundle of three connectors.

if you have further solutions, please post them here.


Thanks for reposting those links. I was just looking for them

will my gear be damaged by using a 1x3 pin header?

if i’m connecting the 1x3 header to a 2x3 array of 6 pins, aside from matching the GND orientation, is there anything else I should know about to connect properly?

I found the Sparkfun connectors awkward to work with, especially if you’ve never messed with them before aside from plugging them in.

I ordered 6 (so I’d have extra for other projects) and broke 3 of them just figuring out how to separate the two pieces, and another trying to assemble it.

Can anyone recommend a UK/ eu vendor from which to buy ii cables to connect up my Teletype and Just Friends?

Many thanks

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Brian from Monome responded to my email regarding the same thing with a link to this thread:

Basically, it’s just six female-to-female jumper cables. I bought 8" ones off of Amazon (I’m in the US though)

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Thanks that’s great :slight_smile:

tagging you two @bpcmusic @dan_derks
hoping you have info on this…

ordered from bpc and would rather not fry my with or teletype

If anyone would be up for posting a quick how to for total novices that would be awesome. I’m not remotely experienced with building electronics and likewise do not want to fry my beautiful Teletype

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@glia, should be good. In fact, @bpcmusic sells 1x3 cables in his store.

EDIT: read your initial post too quick. I have connected a TX with 2x3 header (and 3 of the slots unconnected to a pin on the TX module), as well as used a 1x3 cable with Just Friends and nothing bad has happened.


Are there any issues with using a longer i2c cable? I’m finding that I’d like to put my Just Friends module on the opposite side of my case where the Teletype is located. I’ve got an ER-301/Earthsea/Ansible also hooked up via the backpack. The cable I’d like to make would be about double/triple the usual length.

It depends, I’ve had some trouble with EM interference on longer I2C lines in some DIY projects (not in your application though). The I2C protocol recommends short lines as well. It really depends on the total capacitance of your cable and the value of the pull-up resistors in your machine.

there’s been many posts on this. female to female dupont cables, only need 3 per link. i bought extras plus male to female for custom long cables. i used these and electrical tape:

HiLetgo 200pcs/5x40pcs Breadboard Jumper Wires Dupont Wire Male to Male, Male to Female, Female to Female, 2.54mm to 2.54mm, 2.54mm to 2.0mm, 2.0mm to 2.0mm 20CM Cables Assortment Kit for Arduino DIY

don’t plug shit in wrong!

i know they say it can’t fry your modules, but since my ansible just died (thanks for the replacement, brian!), i am now extra careful. i was dealing with faulty power or the i2c rats nest that was with the teletype, ansible, just friends, er301, and w/ all wired up in a 3u skiff.

For anyone else who might have been waiting for the back order items to fill at sparkfun, I found them at Karlsson Robotics as well: Ribbon Cable & Ribbon Crimp Connector.

Would these be OK?

just seeing you tagged me in a subsequent post after searching to see if this very question had been answered – reconfiguring my case and the standard 2x3 cable is too short for the distance I need b/w TT and JF. I was going to use the 1x3 I got from @bpcmusic a few months ago – this is a-ok, yeah?

I’d be lying if i said I had a comprehensive answer so i’ll re-test sometime this weekend

but fwiw my rack never fried itself the few times i used it this summer.

to make an i2c bus, just make sure all the GND are touching, all the SDA, all the SCL. it doesn’t matter what kind of cable you use, how many contacts.

we used 2x3 cables because they’re easy to make. 1x3 cables are more ergonomic. hand-wired single cables are totally fine.

you’re good!


Hi guys, late to the party, got Mannequins W/ today and realized I haven’t bought an i2c cables along. Sadly the i2c socket from W/ is ‘just fit’, sides got blocked by two sandwiched PCBs so a normal 5 x 2 pins bus cable is not appropriate.

What I need is a daisy chained cable for connecting TT with JF and W/, do you guys know where can find one? Thanks!


you can use these breadboard cables, a 2x5 cable is in any case not the right choice.

If you want to use several I²c modules on the same bus, it’s recommened to use the Teletype Bus board