STEMMA Qwiic cables

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MonsterJoe
 
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STEMMA Qwiic cables

Post by MonsterJoe »

Hi,

I hope this is the right forum for this. To connect a bunch of your boards, I'd need to make my own cables.

However I can't find the right kit for that. Could you point me into the right direction?

I am talking, for example, about this: https://www.adafruit.com/product/5626. What would I need to make my own cables to connect to that?

Bonus: Also, I know i2c cables can only have a limited length (1-2m max). Does chaining them change any of that?

If this seems like a stupid question, it probably is. I am still new to all of this, so my google fu fails me. I did spend a few hours searching, but for somehow this topic still eludes me.

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adafruit_support_bill
 
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Re: STEMMA Qwiic cables

Post by adafruit_support_bill »

We do stock a selection of STEMMA cables: https://www.adafruit.com/product/4399

The connector used is a 4-pin JST SH.
https://www.jst-mfg.com/product/index.php?series=231
We do stock the jacks here: https://www.adafruit.com/product/4208

For the plugs, pins & crimping equipment, check with Mouser or DigiKey.
Bonus: Also, I know i2c cables can only have a limited length (1-2m max). Does chaining them change any of that?
It doesn't matter if you chain them end-to-end or in a star configuration. The limiting factor is the total length of all the connected cabling. Things usually start getting dicey somewhere beyond a meter or so.

There is some capacitance between the parallel wires in the cable. The longer the cable, the larger the capacitance. Capacitance tends to round-off the edges of the signal pulses on the cable. Too much of it will start to interfere with proper communication.

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MonsterJoe
 
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Re: STEMMA Qwiic cables

Post by MonsterJoe »

Thanks a lot! I will look for JST SH.

I thought that maybe the signal would get re-emmitted or something like that. But I guess it's just one line going all the way through without any magic.

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adafruit_support_bill
 
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Re: STEMMA Qwiic cables

Post by adafruit_support_bill »

We do have an active terminator board that can help keep the signals in shape with longer runs: https://www.adafruit.com/product/4756

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MonsterJoe
 
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Re: STEMMA Qwiic cables

Post by MonsterJoe »

Thanks, going to grab a few of those as well then to try it out. Maybe lower clock rate already helps if there is an issue.

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adafruit_support_bill
 
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Re: STEMMA Qwiic cables

Post by adafruit_support_bill »

Yes, a lower clock rate can be helpful too. Obviously that limits the throughput as well. But not all applications require maximum speed.

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