Figure 283. Bus Transfer Diagrams For Smbus Master Transmitter - ST STM32F423 Reference Manual

RM0430
When the SMBus master wants to send a RESTART condition after the PEC, software
mode must be selected (AUTOEND=0). In this case, once NBYTES-1 have been
transmitted, the FMPI2C_PECR register content is transmitted and the TC flag is set after
the PEC transmission, stretching the SCL line low. The RESTART condition must be
programmed in the TC interrupt subroutine.
Caution: The PECBYTE bit has no effect when the RELOAD bit is set.
Fast-mode Plus Inter-integrated circuit (FMPI2C) interface

Figure 283. Bus transfer diagrams for SMBus master transmitter

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