RM0401 Rev 3 659/771
RM0401 Universal synchronous receiver transmitter (USART) /universal asynchronous receiver
679
Figure 227. USART data clock timing diagram (M=1)
Figure 228. RX data setup/hold time
Note: The function of SCLK is different in Smartcard mode. Refer to the Smartcard mode chapter
for more details.
24.4.10 Single-wire half-duplex communication
The single-wire half-duplex mode is selected by setting the HDSEL bit in the USART_CR3
register. In this mode, the following bits must be kept cleared:
• LINEN and CLKEN bits in the USART_CR2 register,
• SCEN and IREN bits in the USART_CR3 register.
The USART can be configured to follow a single-wire half-duplex protocol where the TX and
RX lines are internally connected. The selection between half- and full-duplex
communication is made with a control bit ‘HALF DUPLEX SEL’ (HDSEL in USART_CR3).
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