STM32G4 -- Flash via I2C-Bootloader Problem

[Ananthu]

Hi,

We are facing the same issue like the below community post.

https://community.st.com/t5/stm32-mcus-products/flash-via-i2c-bootloader-problem-for-stm32g0b1kbu6/m-p/636467#M234685

But we are using  'STM32G431RBT6' in our project, kindly let us know if any specific pins need to be handled in this MCU for proper operation.

Kindly reply on this as early as possible.

Thanks,

Ananthu

[STOne-32]

Dear @Ananthu ,

can you let us know, which exact I2C pins are used for bootloader for your STM32G431RBT6 - LQFP64 device?

Thank you for the details.

STOne-32.

[Ananthu]

Hi,

We are using PC8 (SCL) and PC9 (SDA) for bootloader. 

Thanks,

Ananthu

[TDK]

There is nothing special you need to do here. Boot into the bootloader and use PC8/PC9 to communicate. Ensure other bootloader interfaces are quiet during this period.

[Ananthu]

We haven't faced any issue on the first lot boards, this issue is created in latest lot boards.

Sometimes the SCL is getting hold to LOW while boot loader stage.

Other bootloader interfaces are quiet during this stage.

Do we need to pull up the PA12 (USB DP) pin for proper operation (as mentioned in the other community post)?

[STOne-32]

Dear @Ananthu ,

It might be similar to the same description on STM32G0 series with "I2C stretches the line on the connection causing
issues with some I2C Hardware hosts", Introduction to system memory boot mode on STM32 MCUs - Application note  Page 241, may be a floating pin is creating similar behavior as you said  above.   Recommendation to try to Pull-up them to VDD and check with the failing devices if they recover ?

This is just a Hypothesis to check. Thank you.

STOne-32

[Ananthu]

Hi,

We have tried PA12, PA10, PA3, and PC11, both individually and in combination, with pull-ups enabled, but it did not work as expected.
Could you please let us know if there are any other dependencies or requirements for the bootloader?

Attached the latest and old lot MCU pics, FYR.

can you infer any change in this? If so, kindly let us know.

[Ananthu]

Hi,

Can you please reply on this as early as possible?

Our production boards are on hold due to this issue.

[TDK]

What are you looking for? Can you share a logic analyzer plot of SDA/SCL when you try to connect?

If this worked on older hardware but is no longer working, it's probably an issue with the new hardware, not the chip. Is bootloader version the same? Unlikely to be a magic solution here. Can you share schematic?