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Original question:

DS90UB954-Q1: The speed of I2C

DS90UB954-Q1: i2c rate

Yue
Prodigy 110 points
Part Number: DS90UB954-Q1

What's the meaning of 7.5.3.1 Remote I2C Slaves Data Throughput  in 954 datasheet 

1)I'm not sure the meaning of host i2c and remote i2c rate.Dose host i2c rate mean rate of cpu and 954, remote i2c rate mean rate of 953 and sensor? 

2)"The local I2C rate is based on the host controller clock rate, while the remote rate depends on the settings for the proxy I2C master (SCL frequency). "  Dose "the proxy I2C master" mean 953?

3)Why add (Remote_bit * 9)  and FCdelay when calculate Effective rate ?

Thanks!

Yue

  • 0
    TI__Expert 5480 points

    Hello Yue, 

    1. Yes, host i2c is the local i2c. Remote i2c rate is the connect devices. If you are connected to the 954 directly (host), then 953 (remote). 

    2. Yes, in the case of the example in question 1, 953 would be the master proxy. 

    3. While communicating to a remote device over the serial link, each I 2C data byte is buffered and regenerated on the remote side of the link, so you will need to include these because the reduction of throughput is dependent on the operating frequencies of the local and remote interfaces. 

    Thanks, 
    Sally 

  • 0 in reply to Sally Cheung95
    Prodigy 110 points

    Hi Sally,

    Thank you for your reply.And if I use 2 couples of fpd-link,can i coummunicate with the second 953 right by i2c?

    It's like that   host--(954--953)--(954--953)--sensor  ,if we use like this ,could i2c work as expected?

  • 0 in reply to Yue
    TI__Expert 5480 points

    Hello, 

    Is that 2x953 connected to both ports of the 954? If so, yes it can communicate to both. 

    Thanks, 
    Sally 

  • 0 in reply to Sally Cheung95
    Prodigy 110 points

    Hi Sally

    I'm sorry it's not like what you think.

    I want to use a 954 link to a 953,and this 953's i2c is linked to another 954's,and this 954 links to another 953.

    So it's like     host - (954-953)-----(i2c&Mipi)-----(954-953)---sensor

    I'm not sure if host could communicate with the red 954&953 well.

    If they can work like this,what should I pay attention to when use i2c?

  • 0 in reply to Yue
    TI__Guru** 103215 points

    Hello Yue,

    Yes this is possible. You just need to configure I2C pass through on the devices in the middle and you can address any device in this chain 

    Best Regards,

    Casey