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CHAPTER 13 UART
13.6.2 Reception Operations (Operating Mode 0, 1, or 3)
When data is received at the serial data input pin, the internal reception shift register
converts it from serial to parallel. If the data is correctly transmitted up to the stop
bit(s), data in the internal shift register is transferred to the SIDR register, then "1" is set
to the RDRF bit.
■ Reception Operations (Operating Mode 0, 1, or 3)
If an overrun error or framing error occurs, the received data is not transmitted to the SIDR register, but the
ORFE bit is set to "1".
Either of the RDRF bit and ORFE bit goes on when the final stop bit is detected after data is fully received.
If the reception interrupt is enabled (SSD: RIE = 1), an interrupt request to the CPU (IRQ6) is generated.
When the RDRF bit goes on, the received data has been transmitted to the SIDR register.
In operating mode 2, when the RIE bit is "1", RDRF bit or ORFE bit is "1", and reception interrupt pin is
"1", the mode 2 UART reception interrupt request is output to the CPU.
Note:
In operating mode 1, the parity bit is read as data in the 7th bit. Set up the program so that the 7th bit is
not read.
Figure 13.6-4 , Figure 13.6-5 , and Figure 13.6-6 show the reception operations when parity is not used and
the number of stop bits is "1" in operating mode 0, 1, or 3.
Figure 13.6-4 Reception Operations in Operating Mode 0, 1, or 3
RDRF
STOPSTART
01234567
Data
Reception
interrupt