TCA9554A: update output ports

Yusuke Mukuno said:

Part Number: TCA9554A

HI expert,

Can TCA9554A update output ports in case of continues data writing of I2C?

- Start bit

- Slave address

- Register address

- Write Data (Output setting 1)

- Write Data (Output setting 1)

.

.

- Write Data (Output setting N)

- Stop bit

From Figure 23. the timing of data output from port is after writing data. So I believe, it can update each write data timings. Is it correct? 

This is an interesting question, I actually don't know off the top of my head if the output pins for this device will actually support changing their outputs with each ACK in a continuous write sequence like you are suggesting. My guess is our device requires a stop condition otherwise it will not update its output. I do believe our PCF devices do support this kind of functionality as I did testing for this last week and found that they will update after each ACK but this device actually has registers, so the state machine is different than the PCF devices. Would you like me to order samples and test the TCA9554A for this capability?

Also, Do you have any idea for I/O expander that is controllable as below?  (use case is OUTPUT only)

- Start bit

- Slave address

- Write Data

- Stop bit

Yes, our PCF8574 device.

Thanks

Muk