the time lag from Input(default) to Output of PCA6524HE

[Edgard]

Dear an Engineer in NXP

I tried to increase Output port with NXP PCAL6524, but I met a trouble.
After power-on or Reset assert sequence, I/O port  (configured as an output) outputted one pulse, about 40msec.

I would like to remove the pulse, however I didn't know why the pulse appeared.

According to the datasheet 6.6, the I/O port is configured as an input.
Then the port is configured as an output by I2C command in order to modify the register set.

I have one question, is it true that the pulse about 40msec is outputted while changing the register set from Input(default) to Output?

Thanks in advance.

[JozefKozon · Accepted solution]

Dear Yomogita-san,

please connect an oscilloscope to the I/O pin and please share the scope. By default the Output port registers are set to 1 for each pin. You can try to set the Output port register bits to 0 first and later change the input pins to output. This way the pulse should be eliminated. 

Change the pins to outputs.

With Best Regards,

Jozef

[Edgard]

Dear Jozef-san

thanks for your support.

As you said, I tried to set the register.
Then the pulse which I didn't want was disapeared.

Thank you.

Kindest Regards
  Edgard