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TCA9534A: never acknoledge

Part Number: TCA9534A
Other Parts Discussed in Thread: LM75B, TCA9534,


I am having issue getting a TCA9534APWR to work on my prototype.

I ma using a PIC32 as I2C master, with library I have used with no problem for years.

On the same I2C line, is connect a temperature sensor (LM75B) that works like a charm.

My issue is that the TCA9534 does not acknoledge after sending the slave address. This prevents me to get any further in the communication, an dtherefore to use this IC.

When sending 0b0100 0000 (0b0100 000 + last bit at 0 for write), the SDA line goes high on the ninth SCL clock tick.

I did try all possible address for this device (0b0100 A2 A1 A0), just in case : no change.

Signal quality not optimal, but should be good enough.

I have tried several thing, but nothing helped :

- Check soldering
- Check layout
- Swap the IC for a brand new one
- Change the pull-up resistors with different values
- Remove the LM75B that uses the same I2C
- Reduce clock frequency
- Increase clock frequency

Is there anything that I am missing to get this IC to work ?

Many thanks.