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Figure 76 Break Frame Detection in Idle State
RX
FEFLG
Data 1
Data 2
Idle
frame
Data 3
Break frame
Data 4
USART_DATA
Data 1
0x00
Data 4
Data 2
Data 3
LBDFLG
Data 5
Break frame detection in data transmission state
In the process of data transmission, if the RX pin detects the break frame, the
currently transmitted data frame will generate FEFLG.
Figure 77 Break Frame Detection in Data Transmission State
RX
FEFLG
Data 1
Data
2
Data 3
Break
frame
Data 4
USART_DATA
Data 1
Data 3
Data 2
Data 4
LBDFLG
Data
2
Smart card mode
Smart card mode is a single-line half-duplex communication mode. The
interface supports ISO7816-3 standard protocol and can control the reading and
writing of smart cards that meet the standard protocol.
SCEN bit of USART_CTRL3 register decides whether to enter the smart card
mode.
When USART enters the smart card mode:
The LINMEN bit of USART_CTRL2 register, and IREN and HDEN bits
of USART_CTRL3 register must be cleared.
The data frame format is 8 data bits and 1 check bit, and 0.5 or 1.5
stop bits are used. (To avoid switching between two configurations, it
is recommended to use 1.5 stop bits when transmitting and receiving
data)
CLKEN bit of USART_CTRL2 can be set to provide clocks for smart
card.