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CHAPTER 16 ASYNCHRONOUS SERIAL INTERFACE (UART)
User’s Manual U16890EJ1V0UD
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16.2 Configuration
Table 16-1. Configuration of UARTn
Item
Configuration
Registers
Receive buffer register n (RXBn)
Transmit buffer register n (TXBn)
Receive shift register
Transmit shift register
Asynchronous serial interface mode register n (ASIMM)
Asynchronous serial interface status register n (ASISn)
Asynchronous serial interface transmit status register n (ASIFn)
Other
Reception control parity check
Addition of transmission control parity
Remark
n = 0, 1
Figure 16-1 shows the configuration of UARTn.
(1) Asynchronous serial interface mode register n (ASIMn)
The ASIMn register is an 8-bit register for specifying the operation of UARTn.
(2) Asynchronous serial interface status register n (ASISn)
The ASISn register consists of a set of flags that indicate the error contents when a reception error occurs.
The various reception error flags are set (1) when a reception error occurs and are cleared (0) when the
ASISn register is read.
(3) Asynchronous serial interface transmit status register n (ASIFn)
The ASIFn register is an 8-bit register that indicates the status when a transmit operation is performed.
This register consists of a transmit buffer data flag, which indicates the hold status of the TXBn register data,
and the transmit shift register data flag, which indicates whether transmission is in progress.
(4) Reception control parity check
The receive operation is controlled according to the contents set in the ASIMn register. A check for parity
errors is also performed during a receive operation, and if an error is detected, a value corresponding to the
error contents is set in the ASISn register.
(5) Receive shift register
This is a shift register that converts the serial data that was input to the RXDn pin to parallel data. One byte
of data is received, and if a stop bit is detected, the receive data is transferred to the RXBn register.
This register cannot be directly manipulated.
(6) Receive buffer register n (RXBn)
The RXBn register is an 8-bit buffer register for holding receive data. When 7 characters are received, 0 is
stored in the MSB.
During a reception enabled state, receive data is transferred from the receive shift register to the RXBn
register, synchronized with the end of the shift-in processing of one frame.
Also, the reception completion interrupt request signal (INTSRn) is generated by the transfer of data to the
RXBn register.