TDA4VEN-Q1: About the I2C fan-out number

Furuna Yamamoto

Part Number: TDA4VEN-Q1

Hi.

In our prototype under development, there are 8 I2C slave devices connected (Master: TDA4VEN, Slaves: 8 devices).

However, because there are many slave devices, we found that the rising edges of the communication waveform are slow, and the waveform has a low slew rate.

1) Could you tell us the recommended fan-out number?
2) As a countermeasure, we are considering increasing the number of I2C buses. We are currently using WKUP_SCL/SDA, but is it possible to use other I2C interfaces? (e.g., MCU_I2C0_SCL/SDA)
The purpose is for register initialization and periodic monitoring.
3) If there are any other countermeasure ideas, please let us know.

3 months ago

0 Vinit Patel 3 months ago

TI__Intellectual 2970 points

Hi Furuna Yamamoto,

Allow us some time.

We will get back to you ASAP.

Thanks for being patient.

Regards,

Vinit

0 Vinit Patel 3 months ago

TI__Intellectual 2970 points

Hi Furuna Yamamoto,

what SDK and its version are you using?

with I2C, which mode are you using?

What is your goal to achieve with i2c communication?

Some additional details which you think better to know for debugging.

Regards,

Vinit

0 Furuna Yamamoto 3 months ago in reply to Vinit Patel

Intellectual 400 points

Hi. Vinit-san,

>what SDK and its version are you using?

- ti-processor-sdk-linux-adas-j722s-evm-11_01_00_03
- ti-processor-sdk-rtos-j722s-evm-11_01_00_04

>with I2C, which mode are you using?

- FastMode (400k bps)

>What is your goal to achieve with i2c communication?

- Initial settings (register settings) and periodic monitoring of various ICs

>Some additional details which you think better to know for debugging.

- There is none.

0 Vinit Patel 3 months ago in reply to Furuna Yamamoto

TI__Intellectual 2970 points

Hi Yamamoto-san,

We are on it. Expect some delay due to weekend.

Reagards,

Vinit

0 Vinit Patel 3 months ago in reply to Vinit Patel

TI__Intellectual 2970 points

Hi Yamamoto-san,

Would reducing I2C speed from 400 kHz to 100 kHz be acceptable for your register initialization and monitoring application?

If yes then try reducing the speed to 100kHz (Standard mode) and let me know what impact does this have on the working.

Regards,

Vinit

0 Furuna Yamamoto 3 months ago in reply to Vinit Patel

Intellectual 400 points

Hi, Vinit-san,

Thank you for your suggestion. I will check whether the performance is satisfactory at 100 kHz.

What do you think about the following idea?

> As a countermeasure, we are considering increasing the number of I2C buses. We are currently using WKUP_SCL/SDA, but is it possible to use other I2C interfaces? (e.g., MCU_I2C0_SCL/SDA)

Regards,

+1 Vinit Patel 3 months ago in reply to Furuna Yamamoto

TI__Intellectual 2970 points

Hi Yamamoto-san,

Furuna Yamamoto said:
As a countermeasure, we are considering increasing the number of I2C buses. We are currently using WKUP_SCL/SDA, but is it possible to use other I2C interfaces? (e.g., MCU_I2C0_SCL/SDA)

yes you can go for this approach as well.

You can use i2c bus extenders to connect all the slave devices to one single i2c bus.

Regards,

Vinit

0 Furuna Yamamoto 3 months ago

Intellectual 400 points

Hi Vinit-san,

Is it possible to change the termination resistor from 2.2kΩ to 500Ω? I am particularly concerned about the input current to the TDA4VEN O.D.

In the next prototype, we plan to add an I2C Expander, but the currently evaluated board cannot accommodate it.

Therefore, as a temporary measure, we are considering applying a method that allows the waveform to fluctuate in amplitude.

0 Vinit Patel 3 months ago in reply to Furuna Yamamoto

TI__Intellectual 2970 points

Hi Yamamoto-san,

i would suggest you to follow the datasheet - section 6.7.1 - which has the details about the open drain, failsafe electrical characteristics.

I would request you create an another query for this question as its now about the hardware.

Regards,

Vinit

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TDA4VEN-Q1: About the I2C fan-out number