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Chapter 13
Serial Interface Function
Preliminary User’s Manual U15839EE1V0UM00
13.2.2 Configuration
UART5n is controlled by the asynchronous serial interface mode register (ASIMn), asynchronous serial
interface status register (ASISn), and asynchronous serial interface transmission status register
(ASIFn). Receive data is maintained in the reception buffer register (RXBn), and transmit data is written
to the transmission buffer register (TXBn).
Figure 13-1, “Asynchronous Serial Interfaces Block Diagram,” on page 366 shows the configuration of
the asynchronous serial interface (UART5n) (n = 0, 1).
(1)
Asynchronous serial interface mode registers (ASIM0, ASIM1)
The ASIMn register is an 8-bit register for specifying the operation of the asynchronous serial
interface.
(2)
Asynchronous serial interface status registers (ASIS0, ASIS1)
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 reset
(0) when the ASISn register is read.
(3)
Asynchronous serial interface transmission status registers (ASIF0, ASIF1)
The ASIFn register is an 8-bit register that indicates the status when a transmit operation is
performed.
This register consists of a transmission buffer data flag, which indicates the hold status of TXBn
data, and the transmission 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)
Reception shift register
This is a shift register that converts the serial data that was input to the RXD5n pin to parallel data.
One byte of data is received, and if a stop bit is detected, the receive data is transferred to the
reception buffer register (RXBn).
This register cannot be directly manipulated.
(6)
Reception buffer registers (RXB0, RXB1)
RXBn 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 reception shift register to the
RXBn, synchronized with the end of the shift-in processing of one frame.
Also, the reception completion interrupt request (INTSRn) is generated by the transfer of data to
the RXBn.
(7)
Transmission shift register
This is a shift register that converts the parallel data that was transferred from the transmission
buffer register (TXBn) to serial data.
When one byte of data is transferred from the TXBn, the shift register data is output from the TXDn
pin.
This register cannot be directly manipulated.
Содержание mPD703128
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