I2C issue with STM32H7 MCU

[Edwin kaus]

Posted on June 11, 2018 at 19:14

Hello.,.,

 I am using STM32H7 newly released MCU in our project,  In this 3 slave devices are connected thorough I2C interface (Audio codec,EEPROM,RTC devices), All slave devices are accessible and working fine with room temperature , But when we tested the same unit with 70 Celcius temperature The I2C link become unreliable . Can anyone suggest what could be done to resolve this issue I tried by changing I2C clock in both higher and lower values (Currently I2C clock @ 100KHZ) but end up with same status. 

Also during analysis I observed a bug with the Micro controller(STM32H765BIT),  A default 200KHZ is generated from contoller (Through PIN 101, same pin i am using as I2C clock pin ), even I erased the complete the flash still by default clock is coming out (I cross checked by removing VCC from MCU , that time clock is not coming ) , I suspecting This could be the one reason that makes I2C unreliable.  

Can some STM people spare some time to resolve this issue , We stuck on this issue for long time, Any small help would be appreciated lot.

Thank you., 

#stm32 #i2c-isues

[Amel NASRI]

Posted on June 25, 2018 at 18:40

Hi

karthikshivanna.94

‌,

To more understand your issue, could you please add more details:

1- could you please precise the device you are using? In

https://www.st.com/content/st_com/en/products/microcontrollers/stm32-32-bit-arm-cortex-mcus/stm32-high-performance-mcus/stm32h7-series.html

family, only lines H743 and H753 are available.

2- How exactly is I2C link unreliable at 70°C?

3- Are you using your own hardware or an ST board?

4- What other peripherals than I2C are being used?

5- When seeing a 200KHz on pin 101: is this behaviour observed only at 70°C? are you sure that the flash is really erased? check again using STLink Utility.

-Amel

[Edwin kaus]

Posted on June 25, 2018 at 19:56

Hello., 

I am really sorry , I was totally confused , the default click is coming from some external pheriperal at higher temperature not from MCU , .