DS90UB949-Q1: Configure DS90UB949 as I2C slave

Eileen Hu

Part Number: DS90UB949-Q1

Hi team,

I would like to know how to configure DS90UB949 as I2C slave. When communicating with 949 via I2C, it has never response ACK. Could you give some comments? Thank you a lot. Below is the schematic.

BR.

Eileen

2 months ago

0 Fadi Abdulhameed 2 months ago

TI__Mastermind 31480 points

Hey Eileen,

So you're not able to talk to the 949 locally? What are you using as an I2C host? Is this your own PC or an SoC?

Can you please send me the full schematic for review? You can privet message it to me on e2e or email it to me (f-abdulhameed@ti.com) if you don't want to paste it here.

For I2C communication the main things you want to check is the following:

Ensure the 949 is powered up correctly (VDDs high / PDB high) following datasheet power up sequence recommendation in datasheet
Ensure SDA/SCL have the correct pull-up resistor to the correct voltage
Ensure IDx is strapped to the correct mode
Use ALP information tab or scripting tab to capture I2C information

- Fadi A\.

0 Eileen Hu 1 month ago in reply to Fadi Abdulhameed

TI__Prodigy 580 points

Hi Fadi,

I2C host is an MCU. And It's difficult to let customer to share the full schematic with me. There are 4.7kohm pull-up resistors connected to 3.3V at SDA/SCL. The MCU is connected to SDA, SCL, PDB, and INTB. Is there anything else that needs to be connected to MCU?

PDB is connected to MCU directly, without pull-up resistor and a capacitor. Will this cause the I2C to fail to communicate?

The customer has checked the points you mentioned, but it still doesn.t work. Do you have any other comments?

Below is a waveform of I2C.