Other Parts Discussed in Thread: TMUX1208, SN74LVC1G34, DRV2605, TCA9617A, TCA9800, TCA39306, LSF0102, TCA9548A
Hello everyone!
I want to bring to you an issue that I am having with a design of mine.
I want to read from multiple identical devices (I call them Nodes) that are connected to a single central board (that I call Receiver). The receiver has a 3.3V power, that also supply each of the node. Inside the node, I have a sensor that I want to read from via I2C 1MHz that needs a 1.8V voltage, so I introduced in the node an LDO to go from 3.3V to 1.8V, and a TCA9416 to shift in level the I2C signal. No external pull up resistance in the node.
In the receiver the SDA line is multiplexed using a TMUX1208, and the SCL instead is given to all the nodes (up to 20) using a buffer SN74LVC1G34.
Now, the problem is that I'm having a really hard time to successfully communicate with my nodes: so far, it work only when just one node is connected to the receiver.
This is what I see when I plug 10 nodes
With 2 nodes instead I see
I can see some communication, but overall is unreliable
To isolate the problem, I also tried other devices than the node, and I can see that for example if I plug tw DRV2605 (4.7kOhm pull up resistor) instead of my node, without any TCA9416, I can communicate correctly with both of them without any issue.
Is there anything related to the TCA9416 that can bring this behavior, when the SCL sees a parallel of them? Are there any other suitable devices that It may be worth trying instead of the TCA?