DS90UH947-Q1: I2C Communication to DES

Jared Becker

Part Number: DS90UH947-Q1

Hi Team,

A few questions about I2C communication to the partner DES (assume 948 if specific DES needed)..

1. Lets say that the default I2C address of the 947 is 0x01 and the I2C address of the 948 is 0x02. In order to check registers in the 948, does the Host SoC/MCU just send a command on the I2C lines as follows: readI2C(0x02, desired_register)? Or does something need to be setup in the 947?

2. I see that there is an I2C Passthrough Port0/Port1 bit in the General Configuration (0x03) register of the 947. What exactly does that do? I see the description "Read/Write transaction matching any entry in the Slave Alias registers will be passed through to the remote DES". So does that mean that the Slave and Alias registers are required to perform I2C communication to the DES?

Essentially, I am trying to understand the purpose of the Slave and Alias aspects of the 947 register map and how those work with regard to I2C communication with the DES.

Thank you,

Jared

over 4 years ago

0 Aaron Heng over 4 years ago

TI__Mastermind 36940 points

Hi Jared,

There are two ways that you can read the remote register. The first way is to ensure that you established the link and lock then you can access the remote register from 947 to 948 or from 948 to 947. The second way is if you want to access the remote register from the SoC side then you need to configure the 947 slave alias I2C address so that you can directly read the remote register.

Hope this helps. Let me know if you have any questions.

Aaron

0 Casey McCrea over 4 years ago in reply to Aaron Heng

TI__Guru** 103215 points

Hello Jared,

Also this app note applies to 94x I2C over BCC and may be helpful to address your questions: https://www.ti.com/lit/an/snla222/snla222.pdf?ts=1601651107520&ref_url=https%253A%252F%252Fwww.google.com%252F

0 Jared Becker over 4 years ago in reply to Casey McCrea

TI__Genius 11845 points

Hi Casey,

That app note helped a ton. So lets say the host is trying to communicate to the 948 and checks the following bit -> 0x06[7] and the bit is flagged. That doesn't necessarily mean the entire I2C bus is down, it just means that there may be as little as one bit error in the I2C forward communication channel, correct?

-Jared

0 Casey McCrea over 4 years ago in reply to Jared Becker

TI__Guru** 103215 points

Hey Jared,

Not sure what you mean by 0x06[7]. Which bit are you asking about? Because this doesn't seem to be related to your question

Best Regards,

Casey

0 Jared Becker over 4 years ago in reply to Casey McCrea

TI__Genius 11845 points

Hi Casey,

Sorry for the confusion. This question is related back to this post:

Specifically, in that post, the I2C_CONTROL_2 (Register 0x06), FORWARD_CHANNEL_SEQUENCE_ERROR (bit 7) -> Will indicate if sequence error is detected. I understand a sequence error is related to I2C and command information in the forward channel. So if that bit is flagged on the 948, that doesn't necessarily mean the entire I2C bus is down on the forward channel, it just means that there may be as little as one bit error in the I2C forward communication channel, correct?

-Jared

0 Aaron Heng over 4 years ago in reply to Jared Becker

TI__Mastermind 36940 points

Hi Jared,

Your assumption is correct.

Aaron

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DS90UH947-Q1: I2C Communication to DES