Using the STMF746 DISCO board... looking at the example for USART6 - in the STM32-provided driver code, the software waits for USART.ISR[REACK] to become set.
The documentation shows the TEACK bit (bit 21 of the USART's ISR) but for the life of me, I cannot find REACK in RM0385 (October 2016). It almost appears to be an undocumented bit. From the software, it appears to be bit 22.
Can someone from ST please clarify the existence of this bit, and why it is in the software from ST but not in the reference manual.
(BTW, REACK is referenced in stm32f746xx.h and stm32f7xx_hal_uart.c and stm32f7xx_hal_usart.c)