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CHAPTER 13 SERIAL INTERFACE UART
Preliminary User’s Manual U14581EJ3V0UM00
(c) Transmission
The transmit operation is started when transmit data is written to the transmit shift register (TXS). A start
bit, parity bit, and stop bit(s) are automatically added to the data.
Starting the transmit operation shifts out the data in TXS, thereby emptying TXS, after which a transmit
completion interrupt (INTST) is issued.
The timing of the transmit completion interrupt is shown in Figure 13-7.
Figure 13-7. Asynchronous Serial Interface Transmit Completion Interrupt Timing
TxD (output)
D0
D1
D2
D6
D7
Parity
STOP
START
INTST
(i) Stop bit length: 1 bit
TxD (output)
D0
D1
D2
D6
D7
Parity
START
INTST
(ii) Stop bit length: 2 bits
STOP
Caution
Do not rewrite the asynchronous serial interface mode register (ASIM) during a transmit
operation. Rewriting to the ASIM register during a transmit operation may disable
further transmit operations (in such case, enter a RESET to restore normal operation).
Whether or not a transmit operation is in progress can be determined by software using
the transmit completion interrupt (INTST) or the interrupt request flag (STIF) that is set
by INTST.
Summary of Contents for mPD780852 Series
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