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By Carnivore
#206317
Notes: Setup
Master Side:
1x Arduino
1x PCA9615

Daisy Chain intermediate
2x PCA9615

Sensor Side
1x PCA9615
1x temperature sensor

I've tried to chaise chain 2x PCA9615 as a intermediate but it doesn't seem to recognize the sensor. Is it possible to use multiple PCA9615 as a switch?
#206374
Hi Carnivore.

I'm not sure exactly why it doesn't work, but in my experience, these are only good for a point to point link and you can't have anything in between. The topology I've found that works is:
Works:
I2C Host-->PCA9615-->CAT5-->PCA9615-->I2C Device(s)

Doesn't work:
I2C Host-->PCA9615-->CAT5-->PCA9615-->I2C-->PCA9615-->CAT5-->PCA9615-->I2C Device(s)

You can have multiple I2C devices on each end, but you can't break the CAT5 link with another PCA9615 for some reason.
If anyone knows why, I'd love to hear the reason.

You can do multiple PCA9615's on the host side going out to multiple remote PCA9615's, you just can't tap into the I2C network in the middle of a CAT5 link.
#206430
Thanks for the quick reply @TS-Chris

What I'm trying to go for is basically

[I2C Host— PCA9615]<—cat5—> [PCA9615— PCA9615]<—cat5—>[PCA9615-I2C Device]

I'd like to turn [PCA9615— PCA9615] into a PCA9615 hub such as
[PCA9615— PCA9615— PCA9615— PCA9615— PCA9615— PCA9615— PCA9615]
#206455
Hi Carnivore.

I don't know the technical reason why, but the setup you're trying won't work. For some reason you can't daisy chain these boards but you can have multiple parallel setups running together.

This would work and you can have I2C devices on both the host and remote side
linear.jpg
This would also work.
star.jpg
Things break down when you try adding another PCA9615 to the remote side. I'm not sure what causes this to break but for some reason it doesn't work.
hub.jpg
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#206456
@TS-Chris

Thanks for the diagrams.

I've tried multiple pull up resistors ranging from 1-10k ohm with no success.

Is there another solution to daisy chain it with my setup? What about wiring rj45 ports in parallel with each other as an intermediate? More like an ethernet splitter design.
#206477
Is there another solution to daisy chain it with my setup?

Unfortunately I don't know of one.

What about wiring rj45 ports in parallel with each other as an intermediate?

You could give that a try but we haven't tested it and I'm fairly certain it wouldn't work.

More like an ethernet splitter design.
As far as I know, nothing like that exists.