DS90UB635-Q1: Can DS90UB635-Q and S90UB638-Q1 support I2C burst mode?

Kazuya,

Thanks for your inquiry. 

I will look into your request but a few clarification question:

1. Are you planning to send burst I2C locally to the 638 or remotely to the 635?

Glenn 

Hello Glenn,

Thank you very much for your reply.

The data will be send to the I2C device remotely connected to the DS90UB935
Through the DS90UB938, as bellow.

EEPROM <= DS90UB935 <---------DS90UB938<=== Host CPU

Thank you again and best regards,
Kazuya.

Hello Glenn,

I forgot to write the following thing.

Sorry for making you confused.
Please discard  Question 1 and give me the answer to the Question 2

Thank you and best regards,
Kazuya.

Hey Kazuya, 

Let me look into this.

glenn 

Hi Kazuya,

We have a watch dog timer that will not allow this to work. The watch dog timer has to be enabled.

Glenn 

Hi Glenn,

Thank you very much for your reply.
Could I confirm you? Do you mean that I2C burst mode can not be used on this system because the watch dog timer can not be disabled.

Thank you again and best regards,
Kazuya. 

Hi Glenn,

Thank you very much for your reply.

If the time range of I2C burst mode is less than time limitation of the watch dog timer, can I2C burst mode be used?

Thank you again and best regards,
Kazuya. 

Hi Kazuya,

We need the watch dog timer must be enabled 50 microseconds. As long as you don't timeout.

Glenn 

Hi Glenn,

Thank you very much for your strong supports.

Could I ask you the following questions?

Q.

“We need the watch dog timer must be enabled 50 microseconds.”
→Why must watch dog timer 50us be enabled ?
   When the I2C speed is 400kHz, 1 bit speed is 1/400kHz=2.5us/1bit.
   1byte=8bit -> 2.5*8= 20us
　Device Address +Register Address +Data -> approxy 60us(In case of burst mode)
  If we set 50us, will it watch dog timer operate?
  We would like to confirm the term of “I2C Bus watch dog timer “.
  -Between Byte and Byte
             or
  -Start byte to End byte?
  If it means “50 microseconds.”,  it should be set I2C Bus watch dog timer=1sec.
 Could you let us know why the watch dog timer must be enabled 50 microseconds?

Thank you again and best regards,
Kazuya.

HI Kazuya,

The remote writes are start byte to end bite hence the reason you have the 50microsecond. What you can do is increase I2C speed to 1MHz to get more transactions. I will send you an app note about the 50us.

Glenn