Universal synchronous asynchronous receiver transmitter (USART)
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Note: In order to provide correctly the CK clock to the Smartcard when CK is always available When
CLKEN = 1, regardless of the UE bit value, the steps below must be respected:
- UE = 0
- SCEN = 1
- GTPR configuration (If PSC needs to be configured, it is recommended to configure PSC and
GT in a single access to USART_ GTPR register).
- CLKEN= 1
- UE = 1
Bit 10
CPOL
: Clock polarity
This bit allows the user to select the polarity of the clock output on the CK pin in synchronous mode.
It works in conjunction with the CPHA bit to produce the desired clock/data relationship
0: Steady low value on CK pin outside transmission window
1: Steady high value on CK pin outside transmission window
This bit can only be written when the USART is disabled (UE=0).
Note: If synchronous mode is not supported, this bit is reserved and forced by hardware to ‘0’.
Section 29.4: USART implementation on page 837
.
Bit 9
CPHA
: Clock phase
This bit is used to select the phase of the clock output on the CK pin in synchronous mode. It works
in conjunction with the CPOL bit to produce the desired clock/data relationship (see
and
)
0: The first clock transition is the first data capture edge
1: The second clock transition is the first data capture edge
This bit can only be written when the USART is disabled (UE=0).
Note: If synchronous mode is not supported, this bit is reserved and forced by hardware to ‘0’.
Section 29.4: USART implementation on page 837
.
Bit 8
LBCL
: Last bit clock pulse
This bit is used to select whether the clock pulse associated with the last data bit transmitted (MSB)
has to be output on the CK pin in synchronous mode.
0: The clock pulse of the last data bit is not output to the CK pin
1: The clock pulse of the last data bit is output to the CK pin
Caution:
The last bit is the 7th or 8th or 9th data bit transmitted depending on the 7 or 8 or 9 bit
format selected by the M bits in the USART_CR1 register.
This bit can only be written when the USART is disabled (UE=0).
Note: If synchronous mode is not supported, this bit is reserved and forced by hardware to ‘0’.
Section 29.4: USART implementation on page 837
.
Bit 7 Reserved, must be kept at reset value.
Bit 6
LBDIE
: LIN break detection interrupt enable
Break interrupt mask (break detection using break delimiter).
0: Interrupt is inhibited
1: An interrupt is generated whenever LBDF=1 in the USART_ISR register
Note: If LIN mode is not supported, this bit is reserved and forced by hardware to ‘0’. Please refer to