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I2C issue with STM32H7 MCU

Edwin kaus
Associate II
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
2 REPLIES 2
Amel NASRI
ST Employee
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

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

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 , .