DS90UB924-Q1: I2C access just after PDB L to H

Atsushi Hirai

Part Number: DS90UB924-Q1

Hi team,

My customer want to program GPIO setting as soon as device available. According to the datasheet, The I2C ready time is 1ms(max) after PDB.

Is it okay that the customer start I2C communication just after the PDB L to H, repeat same command until UB924 response ACK?
I think it’s no problem but, want your advice.

Regards,

over 4 years ago

0 Hamzeh Jaradat over 4 years ago

TI__Guru** 107810 points

Hello Atsushi,

No, this is not okay. By communicating with the device before fulfilling the I2C ready time you could random values into the wrong register. Hence you must wait for 1ms after PDB is high and then communicate with the device.

0 Atsushi Hirai over 4 years ago in reply to Hamzeh Jaradat

TI__Expert 4910 points

Hamzeh-san,

Really?

I2C transaction is started address byte first, and there is ACK/NACK bit. And then data byte and ACK/NACK.

So the device is ready at the first ACK at address byte, And the following data is reliable I think.

It is not acceptable?

Regards,

+1 Hamzeh Jaradat over 4 years ago in reply to Atsushi Hirai

TI__Guru** 107810 points

Hello Atsushi-san,

yes, this is not recommended. It is recommended to add the delay after pulling PDB high and then do the first I2C communications.

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DS90UB924-Q1: I2C access just after PDB L to H