CHAPTER 10 SERIAL INTERFACE FUNCTION
User’s Manual U14492EJ3V0UD
422
(3) Asynchronous serial interface transmission status register 0 (ASIF0)
The ASIF0 register, which consists of 2-bit status flags, indicates the status during transmission.
By writing the next data to the TXB0 register after data is transferred from the TXB0 register to the
transmission shift register, transmit operations can be performed continuously without suspension even
during an interrupt interval. When transmission is performed continuously, data should be written after
referencing the TXBF0 bit of the ASIF0 register to prevent writing to the TXB0 register by mistake.
This register is read-only in 8-bit or 1-bit units.
7
6
5
4
3
2
<1>
<0>
Address
Initial value
ASIF0
0
0
0
0
0
0
TXBF0
TXSF0
FFFFFA05H
00H
Bit Position
Bit Name
Function
1
TXBF0
This is a transmission buffer data flag.
0: Data to be transferred next to TXB0 register does not exist (When the ASIM0
register’s UARTCAE0 or TXE0 bit is 0, or when data has been transferred to
the transmission shift register)
1: Data to be transferred next exists in TXB0 register (Data exists in TXB0
register when the TXB0 register has been written to)
Caution When transmission is performed continuously, data should be
written to the TXB0 register after confirming that this flag is 0. If
writing to TXB0 register is performed when this flag is 1, transmit
data cannot be guaranteed
.
0
TXSF0
This is a transmission shift register data flag. It indicates the transmission status
of UART0.
0: Initial status or a waiting transmission (When the ASIM0 register’s UARTCAE0
or TXE0 bit is set to 0, or when following transfer completion, the next data
transfer from the TXB0 register is not performed)
1: Transmission in progress (When data has been transferred from the TXB0
register)
Caution When the transmission unit is initialized, initialization should be
executed after confirming that this flag is 0 following the
occurrence of a transmission completion interrupt. If initialization
is performed when this flag is 1, transmit data cannot be
guaranteed.
Содержание V850E/IA1 mPD703116
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