How can I configure START Bits for USART1 of STM32F412xx MCU?

[HVira]

I am using STM32F412CGU6 MCU.

I want to configure USART1 as Half Duplex mode (Single wire mode) with TX only and below configurations:

• Baud-rate = 115200
• Start bits = 1
• Parity = even
• Data bits = 7
• Flow control = off
• Stop bits = 1

But in STM CUBEMX , "Start bits" can not be set/configured. Check attached snapshot for reference.Can you please suggest the way/ code changes for configuring the USART1 with above settings? 

[Uwe Bonnes]

UART always sets one start bit. No need to configure!