PCA9534: Sometimes it stops responding via I2C

Fernando Ramon

Part Number: PCA9534
Other Parts Discussed in Thread: TCA9534, TCA6408A

Tool/software:

Hello.

We have an application built using the PCA9534 as an I/O expansion via I2C.

The problem is that sometimes the chip stops responding via I2C, leaving the digital outputs active and unable to be updated from the master (It may be due to electrical disturbances.).

The only way to get it to respond again is to remove power from the device and then re-power it.

I am attaching a connection diagram to see if anyone can advise us on how to strengthen the connection and avoid the problem.

Best regards.

5 months ago

0 Clemens Ladisch 5 months ago

Guru 316690 points

Try the TCA9534 for better power-on behaviour.

The TCA6408A has a /RESET input.

0 Tyler Townsend 5 months ago

TI__Mastermind 47328 points

Hi Fernando,

In addition to Clemens' comments, do you have any oscilloscope captures to show the issue at hand?

Is the SDA bus getting stuck?

Regards,

Tyler

0 Fernando Ramon 4 months ago in reply to Tyler Townsend

Prodigy 10 points

Hello.

Thank you very much for your help.

Unfortunately, this problem doesn't occur in the lab. Therefore, I can't install an oscilloscope or change the hardware. Apparently, the chip stops responding to the master.

Best regards.

0 Tyler Townsend 4 months ago in reply to Fernando Ramon

TI__Mastermind 47328 points

Hi Fernando,

Without scope captures it might be difficult to find a root cause of why the bus is not responding.

Can the MCU communicate with other devices on the bus after the error condition with the PCA9534?

Can we confirm the reading and writing processes are followed according to the datasheet?

Regards,

Tyler

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PCA9534: Sometimes it stops responding via I2C