HAL_I2C_Mem_Read() fail after ST-Link download complete.

[ihbaek.wcabaid]

Chipmodel : STM32L431RBTx

I use M24C04-WDW6TP EEPROM on I2C line and read it using HAL_I2C_Mem_Read() function.

In normal condition, HAL_I2C_Mem_Read() works well. But After download binary to MCU using ST-Link,  1 case in 1000 times try, HAL_I2C_Mem_Read() return error and fail, or retrun success but readout value is invalid.

In in comparison with J-link instead of ST-Link, no read error occurred.  And with simple On/Off test, no error occurred too.

Have you have any similar case like as my?  

[Michal Dudka]

If you stops (to download new binary) MCU somewhere in I2C communication, your slave device can be stucked and wait to complete previous I2C sequence ... and blocks you.

[ihbaek.wcabaid]

Is MX_I2C1_Init() which called STM32 FW inittal stage has no effect to reset I2C block? or insufficient?

How to secure I2C init when ST-Link download?

[S.Ma]

The usual slaves don't reset when the mcu does, and Have you checked bith sda and scl are high before even asking to generate a start bit? If not, do you resync the bus with 9 or 18 stop bits bit bang generated ? Rugged I2C is a brainer.

[Pavel A.]

> with J-link instead of ST-Link, no read error occurred

That's why J-links are so expensive ; )