In slave mode, How to respond NACK when host issue block read protocol

[PYF.1]

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[PYF.1]

Hello everyone,

I have a application on STM32L5xx, I configuration I2C1 to slave mode,

when slave receive first unwanted command code, I want to response NACK to master. I judge the command code in AL_SMBUS_SlaveRxCpltCallback call back function, and set NACK bit at CR2 register but unfortunately cannot success.