Hi Cheuvhave just solved the problem by disabling the NOSTRETCH and ANALOG FLITER bits. And HAL_I2C_Slave_Sequential_Transmit_IT can work perfectly.

My program is very similar to your ones. I use STM32F071 as a slave.when the master device wants to read from STM32F071. it seems HAL_I2C_Slave_Sequential_Transmit_IT cannot send out any data at all. For Master device to write to STM32F071, HAL_I2...