Ii bus board, v2, with pullups

I would also be interested in the board and necessary parts if you are ordering

Great, thanks for the confirmation! On the picture above it does not look as if modifying the teletype would be more elaborate than building the bus board.
I will contemplate about it a bit since I already have the old bus board. On the other hand the board is cheap enough to enjoy the extra i2c connectors…

ok, i’ve had an even better idea for a potentially more elegant solution.

TT is (wonderfully) only one board. the i2c “bus board” could be a thin mezzanine, that connects to both the power jack (with a 5x2 female connector) and the i2c jack (with a 3x2 female connector).

there would then be a load of 3x2 male connectors on the back for i2c, and a male power connector (so there won’t need to be redundant cabling.) the extra regulator and resistors can be hidden on the board. all in all it should be an elegant (and cheap) solution.

of course, i’ve already ordered some of yesterday’s version and that will also be totally fine. so i’ll only make time to draw up this new version if there are other people interested.


Definitely interested. Hoping this ecosystem expands wonderfully and I want a to welcome all my potential new friends.

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Oh, I just ordered the original new bus board PCB - I did not really understand the idea of the new one, technically it does not make any difference, does it?




Also interested in the mezzanine solution, as in addition to solving the “pull-up situation” & providing more i2c connectors it also seems to be a more mechanically sturdy solution than the small bus board PCB.

I dont have any trilogy module so i’ll only have 1 txO connected to my TT. Will this still be a problem for me?

@sam haha, whoa that is embarrassing. i need to improve my reading comprehension skills.

@Leverkusen it will do the exact same thing. this is simply ergonomics.

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In terms of the ergonomics, I found trying to get 3 modules connected to TT and the previous I2C board tricky enough with my current set of I2C cables.I’m wondering if the bus board would be better than a mezzanine solution? Of course, I could also just make myself some longer cables.

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I actually think the ideal is to have both designs available. The best very much depends on the design of the case.

It’s also important to emphasise that whichever solution you choose, beware of short circuits.

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Yes, dummies on the not used males could be smart - would be a bummer when it falls off the tt in a portable case and then touches the power distribution…:zap:

That’s the good thing about ribbon cables!

So, I ordered a v1 bus board just a bit ago. Sounds like the limit for that is 4 devices?

If I wanted to use 2 Ansibles (1 for grid, 1 for arc), a White Whale, a TXo and a TXi, do I need the v2 bus board? I suppose I might add Earthsea at some point as well, oh, and Just Friends, almost forgot about that…

Definitely interested in the v2 bus board!

I’m wondering if you could connect the mk1 board to the mk2?

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ok-- i think this will be the “final” teletype ii expander. connects directly to the back of the TT. 12 headers. power pass-through. i2c pullups set at 2.2k, bringing total i2c pullup resistance to 1.8k. notched for access to reset switch (if you’re programming the firmware and added the switch, that is)

the regulator and resistors are in the middle of the sandwich:

Order from OSH Park

$15 for 3. i just ordered a batch for testing.

here are the source files: tt-i2c-v3.zip (18.7 KB)


of course, now that i’ve ordered, it seems like this board should have the i2c connectors rotated to 90 degrees so cables escape vertically, not stacking up in layers horizontally. opinions?

I’m having a hard time imagining the orientation of the board relative to the teletype because I’m not looking at the back of my teletype right now. But it would be nice if the cables were oriented the same way on all devices, with the ground in a consistent position. (Though I believe Ansible is the odd one out on the position of ground if I remember correctly?)

that’s a good point. perhaps each row could be a different direction. i find a single fold tends to make routing easier…

@tehn - thanks for putting these together. I’ve ordered a set of each from OshPark to test out. Both look great - I’m excited to experiment with them. :slight_smile:

Just adding myself to the list of interested people. I don’t need this white yet, but once the txo/txi are ready I’ll be up to 5 modules on my tt.

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