nonono... the OP is 2 years ago.I use a totally different code, but the same kind of MCU, and have the same issue. When:HAL_SPI_Transmit(); is getting called, (even once) the i2c "busy" flag turns '1'. (and if I reinit I2c, the i2c hall function dies...

Absolutely the same issue with the same MCU (and demo board)Any recommendations?As soon as I enable the SPI, the I2c cease to work (different kind off error flags appear - arbitration error / bus busy, and stuff)Cs.A.